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New submissions for Tue, 19 May 20
- [1] arXiv:2005.07694 [pdf, other]
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Title: Constraining the Reionization History using Bayesian Normalizing FlowsComments: 17 pages, 5 figures. arXiv admin note: substantial text overlap with arXiv:2005.02299Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Machine Learning (cs.LG)
The next generation 21 cm surveys open a new window onto the early stages of cosmic structure formation and provide new insights about the Epoch of Reionization (EoR). However, the non-Gaussian nature of the 21 cm signal along with the huge amount of data generated from these surveys will require more advanced techniques capable to efficiently extract the necessary information to constrain the Reionization History of the Universe. In this paper we present the use of Bayesian Neural Networks (BNNs) to predict the posterior distribution for four astrophysical and cosmological parameters. Besides achieving state-of-the-art prediction performances, the proposed methods provide accurate estimation of parameters uncertainties and infer correlations among them. Additionally, we demonstrate the advantages of Normalizing Flows (NF) combined with BNNs, being able to model more complex output distributions and thus capture key information as non-Gaussianities in the parameter conditional density distribution for astrophysical and cosmological dataset. Finally, we propose novel calibration methods employing Normalizing Flows after training, to produce reliable predictions, and we demonstrate the advantages of this approach both in terms of computational cost and prediction performances.
- [2] arXiv:2005.07707 [pdf, other]
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Title: Effects of Supernova Redshift Uncertainties on the Determination of Cosmological ParametersComments: 13 pagesSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
Redshifts used in current cosmological supernova samples are measured using two primary techniques, one based on well-measured host galaxy spectral lines and the other based on supernova-dominated spectra. Here, we construct an updated Pantheon catalog with revised redshifts, redshift sources and estimated uncertainties for the entire sample to investigate whether these two techniques yield consistent results. The best-fit cosmological parameters using these two measurement techniques disagree, and we explore several possible sources of bias which could result from using the lower-precision supernova-dominated redshifts. In a pilot study, we show that using a host redshift-only subsample of the Pantheon catalog will result in lower $\Omega_m$ and matter density $\Omega_m h^2$ and slightly higher $H_0$ than previous analysis which, among other possibilities, could result in supernova and CMB measurements agreeing on $\Omega_m h^2$ despite tension in $H_0$. To obtain rigorous results, though, the Pantheon catalog should be improved by obtaining host spectra for supernova that have faded and future surveys should be designed to use host galaxy redshifts rather than lower-precision methods.
- [3] arXiv:2005.07709 [pdf, other]
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Title: Frankenstein: Protoplanetary disc brightness profile reconstruction at sub-beam resolution with a rapid Gaussian processComments: 27 pages, 17 figures, accepted in MNRASSubjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM)
Interferometric observations of the mm dust distribution in protoplanetary discs are now showing a ubiquity of annular gap and ring substructures. Their identification and accurate characterization is critical to probing the physical processes responsible. We present Frankenstein (frank), an open source code that recovers axisymmetric disc structures at sub-beam resolution. By fitting the visibilities directly, the model reconstructs a disc's 1D radial brightness profile nonparametrically using a fast (<~1 min) Gaussian process. The code avoids limitations of current methods that obtain the radial brightness profile by either extracting it from the disc image via nonlinear deconvolution at the cost of reduced fit resolution, or by assumptions placed on the functional forms of disc structures to fit the visibilities parametrically. We use mock ALMA observations to quantify the method's intrinsic capability and its performance as a function of baseline-dependent signal-to-noise. Comparing the technique to profile extraction from a CLEAN image, we motivate how our fits accurately recover disc structures at a sub-beam resolution. Demonstrating the model's utility in fitting real high and moderate resolution observations, we conclude by proposing applications to address open questions on protoplanetary disc structure and processes.
- [4] arXiv:2005.07710 [pdf, other]
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Title: Flare Statistics for Young Stars from a Convolutional Neural Network Analysis of $\textit{TESS}$ DataAuthors: Adina D. Feinstein, Benjamin T. Montet, Megan Ansdell, Brian Nord, Jacob L. Bean, Maximilian N. Günther, Michael A. Gully-Santiago, Joshua E. SchliederComments: 20 pages, 17 figures, 1 tableSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Instrumentation and Methods for Astrophysics (astro-ph.IM)
All-sky photometric time-series missions have allowed for the monitoring of thousands of young ($t_{\rm age} < 800$Myr) to understand the evolution of stellar activity. Here we developed a convolutional neural network (CNN), $\texttt{stella}$, specifically trained to find flares in $\textit{Transiting Exoplanet Survey Satellite}$ ($\textit{TESS}$) short-cadence data. We applied the network to 3200 young stars to evaluate flare rates as a function of age and spectral type. The CNN takes a few seconds to identify flares on a single light curve. We also measured rotation periods for 1500 of our targets and find that flares of all amplitudes are present across all spot phases, suggesting high spot coverage across the entire surface. Additionally, flare rates and amplitudes decrease for stars $t_{\rm age} > 50$Myr across all temperatures $T_{\rm eff} \geq 4000$K, while stars from $2300 \leq T_{\rm eff} < 4000$K show no evolution across 800 Myr. Stars of $T_{\rm eff} \leq 4000$K also show higher flare rates and amplitudes across all ages. We investigate the effects of high flare rates on photoevaporative atmospheric mass loss for young planets. In the presence of flares, planets lose 4-7% more atmosphere over the first 1 Gyr. $\texttt{stella}$ is an open-source Python tool-kit hosted on GitHub and PyPI.
- [5] arXiv:2005.07716 [pdf, other]
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Title: ALMA Characterises the Dust Temperature of z ~ 5.5 Star-Forming GalaxiesAuthors: Andreas L. Faisst, Yoshinobu Fudamoto, Pascal A. Oesch, Nick Scoville, Dominik A. Riechers, Riccardo Pavesi, Peter CapakComments: 12 pages, 8 Figures, 3 Table, Submitted to MNRASSubjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
The infrared spectral energy distributions (SEDs) of main-sequence galaxies in the early universe (z > 4) is currently unconstrained as infrared continuum observations are time consuming and not feasible for large samples. We present Atacama Large Millimetre Array (ALMA) Band 8 observations of four main-sequence galaxies at z ~ 5.5 to study their infrared SED shape in detail. Our continuum data (rest-frame 110$\rm \mu m$, close to the peak of infrared emission) allows us to constrain luminosity weighted dust temperatures and total infrared luminosities. With data at longer wavelengths, we measure for the first time the emissivity index at these redshifts to provide more robust estimates of molecular gas masses based on dust continuum. The Band 8 observations of three out of four galaxies can only be reconciled with optically thin emission redward of rest-frame 100$\rm \mu m$. The derived dust peak temperatures at z ~ 5.5 (38$\pm$8K) are elevated compared to average local galaxies, however, 5-10K below what would be predicted from an extrapolation of the trend at $z<4$. This behaviour can be explained by decreasing dust abundance (or density) towards high redshifts, which would cause the infrared SED at the peak to be more optically thin, making hot dust more visible to the external observer. From the 850$\rm \mu m$ dust continuum, we derive molecular gas masses between $10^{10}$ and $10^{11}\,{\rm M_{\odot}}$ and gas fractions (gas over total mass) of 30-80% (gas depletion times of 100-220Myrs). All in all, our results provide a first measured benchmark SED to interpret future millimetre observations of normal, main-sequence galaxies in the early Universe.
- [6] arXiv:2005.07717 [pdf, other]
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Title: Zooming in on Individual Star Formation: Low- and High-mass StarsAuthors: Anna L. Rosen, Stella S.R. Offner, Sarah I. Sadavoy, Asmita Bhandare, Enrique Vázquez-Semadeni, Adam GinsburgComments: 53 pages, 7 figures, To appear in Space Science Reviews (submitted January 31, 2020; accepted May 7, 2020), topical collection on Star formationSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)
Star formation is a multi-scale, multi-physics problem ranging from the size scale of molecular clouds ($\sim$10s pc) down to the size scales of dense prestellar cores ($\sim$0.1 pc) that are the birth sites of stars. Several physical processes like turbulence, magnetic fields and stellar feedback, such as radiation pressure and outflows, are more or less important for different stellar masses and size scales. During the last decade a variety of technological and computing advances have transformed our understanding of star formation through the use of multi-wavelength observations, large scale observational surveys, and multi-physics multi-dimensional numerical simulations. Additionally, the use of synthetic observations of simulations have provided a useful tool to interpret observational data and evaluate the importance of various physical processes on different scales in star formation. Here, we review these recent advancements in both high- ($M \gtrsim 8 \, M_{\rm \odot}$) and low-mass star formation.
- [7] arXiv:2005.07718 [pdf, other]
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Title: Planetary Spin and Obliquity from MergersSubjects: Earth and Planetary Astrophysics (astro-ph.EP)
In planetary systems with sufficiently small inter-planet spacing, close encounters can lead to planetary collisions/mergers or ejections. We study the spin property of the merger products of two giant planets in a statistical manner using numerical simulations and analytical modeling. Planetary collisions lead to rapidly rotating objects and a broad range of obliquities. We find that, under typical conditions for two-planet scatterings, the distributions of spin magnitude $S$ and obliquity $\Theta_{\rm SL}$ of the merger products have simple analytical forms: $f_{S} \propto S$ and $f_{\cos\Theta_{\rm SL}} \propto (1-\cos^2\Theta_{\rm SL})^{-1/2}$. Though parameter studies, we determine the regime of validity for the analytical distributions of spin and obliquity. Since planetary mergers is a major outcome of planet-planet scatterings, observational search for the spin/obliquity signatures of exoplanets would provide important constraints on the dynamical history of planetary systems.
- [8] arXiv:2005.07721 [pdf, other]
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Title: Fast Blast Wave and Ejecta in the Young Core-Collapse Supernova Remnant MSH 15-52/RCW 89Comments: 15 pages, 4 figures, accepted for publication in ApJ LettersSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
One of the youngest known remnants of a core-collapse supernova (SN) in our Galaxy is G320.4$-$1.2/MSH 15-52, containing an energetic pulsar with a very short (1700 yr) spindown age, and likely produced by a stripped-envelope SN Ibc. Bright X-ray and radio emission north of the pulsar overlaps with an H$\alpha$ nebula RCW 89. The bright X-rays there have a highly unusual and quite puzzling morphology, consisting of both very compact thermally-emitting knots and much more diffuse emission of nonthermal origin. We report new X-ray observations of RCW 89 in 2017 and 2018 with Chandra that allowed us to measure the motions of many knots and filaments on decade-long time baselines. We identify a fast blast wave with a velocity of $(4000 \pm 500)d_{5.2}$ km/s ($d_{5.2}$ is the distance in units of 5.2 kpc) with a purely nonthermal spectrum, and without any radio counterpart. Many compact X-ray emission knots are moving vary fast, with velocities as high as 5000 km/s, predominantly radially away from the pulsar. Their spectra show that they are Ne- and Mg-rich heavy-element SN ejecta. They have been significantly decelerated upon their recent impact with the dense ambient medium north of the pulsar. We see fast evolution in brightness and morphology of knots in just a few years. Ejecta knots in RCW 89 resemble those seen in Cas A at optical wavelengths in terms of their initial velocities and densities. They might have the same origin, still not understood but presumably related to stripped-envelope SN explosions themselves.
- [9] arXiv:2005.07726 [pdf, other]
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Title: Pleiades or Not? Resolving the Status of the Lithium Rich M Dwarfs HHJ339 and HHJ430Authors: John Stauffer, Davide Barrado, Trevor David, Luisa Rebull, Lynne Hillenbrand, Eric Mamajek, Rebecca Oppenheimer, Suzanne Aigrain, Herve Bouy, Jorge Lillo-BoxComments: Accepted by AJSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)
Oppenheimer et al. (1997) discovered two M5 dwarfs in the Pleiades with nearly primordial lithium. These stars are not low enough in mass to represent the leading edge of the lithium depletion boundary at Pleiades age (~125 Myr). A possible explanation for the enhanced lithium in these stars is that they are actually not members of the Pleiades but instead are members of a younger moving group seen in projection towards the Pleiades. We have used data from Gaia DR2 to confirm that these two stars, HHJ 339 and HHJ 430, are indeed not members of the Pleiades. Based on their space motions, parallaxes and positions in a Gaia-based CMD, it is probable that these two stars are about 40 parsecs foreground to the Pleiades and have ages of ~25 Myr. Kinematically they are best matched to the 32 Ori moving group.
- [10] arXiv:2005.07739 [pdf, ps, other]
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Title: Lagrangian description of cosmic fluids: mapping dark energy into unified dark energyComments: 7 pages. Comments are welcomeSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc)
We investigate the appropriateness of the use of different Lagrangians to describe various components of the cosmic energy budget, discussing the degeneracies between them, in the absence of non-minimal couplings to gravity or other fields, and clarifying some misconceptions in the literature. We then show that models with the same on-shell Lagrangian may have different proper energy densities and use this result to map dark energy models into unified dark energy models in which dark matter and dark energy are described by the same perfect fluid. We determine the correspondence between their equation of state parameters and sound speeds, briefly discussing the linear sound speed problem of unified dark energy models as well as a possible way out associated to the non-linear dynamics.
- [11] arXiv:2005.07744 [pdf, other]
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Title: Tracking the evolutionary stage of protostars by the abundances of astrophysical icesComments: Accepted for publication in The Astrophysical Journal. 29 pages, 16 figuresSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP); Astrophysics of Galaxies (astro-ph.GA)
The physical evolution of Young Stellar Objects (YSOs) is accompanied by an enrichment of the molecular complexity, mainly triggered by the heating and energetic processing of the astrophysical ices. In this paper, a study of how the ice column density varies across the protostellar evolution has been performed. Tabulated data of H$_2$O, CO$_2$, CH$_3$OH, HCOOH observed by ground- and space-based telescopes toward 27 early-stage YSOs were taken from the literature. The observational data shows that ice column density and spectral index ($\alpha$), used to classify the evolutionary stage, are well correlated. A 2D continuum radiative transfer simulation containing bare and grains covered by ices at different levels of cosmic-ray processing were used to calculate the Spectral Energy Distributions (SEDs) in different angle inclinations between face-on and edge-on configuration. The H$_2$O:CO$_2$ ice mixture was used to address the H$_2$O and CO$_2$ column density variation whereas the CH$_3$OH and HCOOH are a byproduct of the virgin ice after the energetic processing. The simulated spectra were used to calculate the ice column densities of YSOs in an evolutionary sequence. As a result, the models show that the ice column density variation of HCOOH with $\alpha$ can be justified by the envelope dissipation and ice energetic processing. On the other hand, the ice column densities are mostly overestimated in the cases of H$_2$O, CO$_2$ and CH$_3$OH, even though the physical and cosmic-ray processing effects are taken into account.
- [12] arXiv:2005.07748 [pdf, other]
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Title: Convective H-He Interactions in Massive Population III Stellar Evolution ModelsSubjects: Solar and Stellar Astrophysics (astro-ph.SR)
In Pop III stellar models convection-induced mixing between H- and He-rich burning layers can induce a burst of nuclear energy and thereby substantially alter the subsequent evolution and nucleosynthesis in the first massive stars. We investigate H-He shell and core interactions in 26 stellar evolution simulations with masses $15 - 140 \,\mathrm{M}_{\odot}$, using five sets of mixing assumptions. In 22 cases, H-He interactions induce local nuclear energy release in the range $ \sim 10^{9} - 10^{13.5}\, \mathrm{L}_{\odot}$. The luminosities on the upper end of this range amount to a substantial fraction of the layer's internal energy over a convective advection timescale, indicating a dynamic stellar response that would violate 1D stellar evolution modelling assumptions. We distinguish four types of H-He interactions depending on the evolutionary phase and convective stability of the He-rich material. H-burning conditions during H-He interactions give $^{12}\mathrm{C}/^{13}\mathrm{C}$ ratios between $\approx 1.5$ to $\sim1000$ and [C/N] ratios from $\approx -1.7 $ to $\approx 3.2$ with a correlation that agrees well with observations of CEMP-no stars. We also explore Ca production from hot CNO breakout and find the simulations presented here likely cannot explain the observed Ca abundance in the most Ca-poor CEMP-no star. We describe the evolution leading to H-He interactions, which occur during or shortly after core-contraction phases. Three simulations without a H-He interaction are computed to Fe-core infall and a $140\,\mathrm{M}_{\odot}$ simulation becomes pair-unstable. We also discuss present modelling limitations and the need for 3D hydrodynamic models to fully understand these stellar evolutionary phases.
- [13] arXiv:2005.07754 [pdf, ps, other]
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Title: Properties of Galactic B[e] Supergiants: V. 3 Pup -- constraining the orbital parameters and modeling the circumstellar environmentsAuthors: A. S. Miroshnichenko, S. Danford, S. V. Zharikov, V. G. Klochkova, E. L. Chentsov, D. Vanbeveren, O. V. Zakhozhay, N. Manset, M. A. Pogodin, C. T. Omarov, A. K. Kuratova, S. A. KhokhlovComments: 13 pages, 9 figures, 4 tables, accepted in The Astrophysical JournalSubjects: Solar and Stellar Astrophysics (astro-ph.SR)
We report the results of a long-term spectroscopic monitoring of the A-type supergiant with the B[e] phenomenon 3 Pup = HD 62623. We confirm earlier findings that it is a binary system. The orbital parameters were derived using cross-correlation of the spectra in a range of 4460-4632 A, which contains over 30 absorption lines. The orbit was found circular with a period of $137.4\pm0.1$ days, radial velocity semi-amplitude $K_{1} = 5.0\pm0.8$ km s$^{-1}$, systemic radial velocity $\gamma = +26.4\pm2.0$ km s$^{-1}$, and the mass function $f(m) = (1.81^{+0.97}_{-0.76})\times10^{-3}$ M$_{\odot}$. The object may have evolved from a pair with initial masses of $\sim$6.0 M$_{\odot}$ and $\sim$3.6 M$_{\odot}$ with an initial orbital period of $\sim$5 days. Based on the fundamental parameters of the A-supergiant (luminosity $\log$ L/L$_{\odot} = 4.1\pm$0.1 and effective temperature T$_{\rm eff} = 8500\pm$500 K) and evolutionary tracks of mass-transferring binaries, we found current masses of the gainer M$_{2} = 8.8\pm$0.5 M$_{\odot}$ and donor M$_{1} = 0.75\pm0.25$ M$_{\odot}$. We also modeled the object's IR-excess and derived a dust mass of $\sim 5\,\times10^{-5}$ M$_{\odot}$ in the optically-thin dusty disk. The orbital parameters and properties of the H$\alpha$ line profile suggest that the circumstellar gaseous disk is predominantly circumbinary. The relatively low mass of the gainer led us to a suggestion that 3 Pup should be excluded from the B[e] supergiant group and moved to the FS CMa group. Overall these results further support our original suggestion that FS CMa objects are binary systems, where an earlier mass-transfer caused formation of the circumstellar envelope.
- [14] arXiv:2005.07756 [pdf, other]
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Title: Optimized cutting off transit algorithm to study stellar rotation from PLATO mission light curvesAuthors: Leandro de Almeida, Francys Anthony, Ana Carolina Mattiuci, Matthieu Castro, Jefferson Soares da Costa, Reza Samadi, Jose-Dias do Nascimento JrComments: 21 pages, 10 figures, accepted to be published on The Experimental Astronomy (May 14, 2020)Subjects: Solar and Stellar Astrophysics (astro-ph.SR)
Measuring the stellar rotation of one of the components in eclipsing binaries (EBs) or planetary systems is a challenging task. The difficulty is mainly due to the complexity of analyzing, in the same light curve, the signal from the stellar rotation mixed with the transit signal of a stellar or sub-stellar companion, like a brown dwarf or planet. There are many methods to correct the long-term trend of the light curve. However, the correction often erases the signal of the stellar rotation from spots crossing the visible stellar disk and other weaker signals like planets. In this work, we present the DiffeRencial flUx Method of cuTting Off biNariES (DRUM TONES) to identify the signal of the binary transits and disentangle it from stellar rotation planet signals. We present our technique with applications to EBs from CoRoT, Kepler, Kepler K2 and TESS missions. We also applied our method to simulated synthetic EB from the PLATO mission. Our method shows good agreement in the determination of stellar rotation periods for few observed targets from last space missions, as well it is naturally useful for future European missions, such as PLAnetary Transits and Oscillations of stars (PLATO).
- [15] arXiv:2005.07772 [pdf, other]
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Title: Evolving Antennas for Ultra-High Energy Neutrino DetectionAuthors: Julie Rolla, Amy Connolly, Kai Staats, Stephanie Wissel, Dean Arakaki, Ian Best, Adam Blenk, Brian Clark, Maximillian Clowdus, Suren Gourapura, Corey Harris, Hannah Hasan, Luke Letwin, David Liu, Carl Pfendner, Jordan Potter, Cade Sbrocco, Tom Sinha, Jacob TrevithickComments: 8 pages including references, 6 figures, presented at 36th International Cosmic Ray Conference (ICRC 2019)Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Neural and Evolutionary Computing (cs.NE); Instrumentation and Detectors (physics.ins-det)
Evolutionary algorithms borrow from biology the concepts of mutation and selection in order to evolve optimized solutions to known problems. The GENETIS collaboration is developing genetic algorithms for designing antennas that are more sensitive to ultra-high energy neutrino induced radio pulses than current designs. There are three aspects of this investigation. The first is to evolve simple wire antennas to test the concept and different algorithms. Second, optimized antenna response patterns are evolved for a given array geometry. Finally, antennas themselves are evolved using neutrino sensitivity as a measure of fitness. This is achieved by integrating the XFdtd finite-difference time-domain modeling program with simulations of neutrino experiments.
- [16] arXiv:2005.07773 [pdf, other]
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Title: Deep Generative Modeling of Periodic Variable Stars Using Physical ParametersComments: 19 pages, 9 figures, 4 tablesSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
The ability to generate physically plausible ensembles of variable sources is critical to the optimization of time-domain survey cadences and the training of classification models on datasets with few to no labels. Traditional data augmentation techniques expand training sets by reenvisioning observed exemplars, seeking to simulate observations of specific training sources under different (exogenous) conditions. Unlike fully theory-driven models, these approaches do not typically allow principled interpolation nor extrapolation. Moreover, the principal drawback of theory-driven models lies in the prohibitive computational cost of simulating source observables from {\it ab initio} parameters. In this work, we propose a computationally tractable machine learning approach to generate realistic light curves of periodic variables capable of integrating physical parameters and variability classes as inputs. Our deep generative model, inspired by the Transparent Latent Space Generative Adversarial Networks (TL-GANs), uses a Variational Autoencoder (VAE) architecture with Temporal Convolutional Network (TCN) layers, trained using the \hbox{OGLE-III} optical light curves and physical characteristics (e.g., effective temperature and absolute magnitude) from Gaia DR2. A test using the temperature-shape relationship of RR\,Lyrae demonstrates the efficacy of our generative "Physics-Enhanced Latent Space VAE" (PELS-VAE) model. Such deep generative models, serving as non-linear non-parametric emulators, present a novel tool for astronomers to create synthetic time series over arbitrary cadences.
- [17] arXiv:2005.07775 [pdf, ps, other]
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Title: Diffusion of large-scale magnetic fields by reconnection in MHD turbulenceComments: 21 pages, 13 figuresSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA); High Energy Astrophysical Phenomena (astro-ph.HE)
The rate of magnetic field diffusion plays an essential role in several astrophysical plasma processes. It has been demonstrated that the omnipresent turbulence in astrophysical media induces fast magnetic reconnection, which consequently leads to large-scale magnetic flux diffusion at a rate independent of the plasma microphysics. This process is called "reconnection diffusion" (RD) and allows for the diffusion of fields which are dynamically important. The current theory describing RD is based on incompressible magnetohydrodynamic (MHD) turbulence. In this work, we have tested quantitatively the predictions of the RD theory when magnetic forces are dominant in the turbulence dynamics (Alfv\'{e}nic Mach number $M_A < 1$). We employed the \textsc{Pencil Code} to perform numerical simulations of forced MHD turbulence, extracting the values of the diffusion coefficient $\eta_{RD}$ using the Test-Field method. Our results are consistent with the RD theory ($\eta_{RD} \sim M_A^{3}$ for $M_A < 1$) when turbulence approaches the incompressible limit (sonic Mach number $M_S \lesssim 0.02$), while for larger $M_S$ the diffusion is faster ($\eta_{RD} \sim M_A^{2}$).This work shows for the first time simulations of compressible MHD turbulence with the suppression of the cascade in the direction parallel to the mean magnetic field, which is consistent with incompressible weak turbulence theory. We also verified that in our simulations the energy cascading time does not follow the scaling with $M_A$ predicted for the weak regime, in contradiction with the RD theory assumption. Our results generally support and expand the RD theory predictions.
- [18] arXiv:2005.07807 [pdf, other]
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Title: The effects of a background potential in star cluster evolution: a delay in the relaxation time-scale and runaway collision processesComments: 16 pages. Accepted for publication in Astronomy and AstrophysicsSubjects: Astrophysics of Galaxies (astro-ph.GA)
Runaway stellar collisions in dense star clusters are invoked to explain the presence of very massive stars or blue stragglers in the center of those systems. This process has also been explored for the first star clusters in the Universe and shown to yield stars that may collapse at some points into an intermediate mass black hole. Although the early evolution of star clusters requires the explicit modeling of the gas out of which the stars form, these calculations would be extremely time-consuming and often the effects of the gas can be accurately treated by including a background potential to account for the extra gravitational force. We apply this approximation to model the early evolution of the first dense star clusters formed in the Universe by performing $N$-body simulations, our goal is to understand how the additional gravitational force affects the growth of a very massive star through stellar mergers in the central parts of the star cluster. Our results show that the background potential increases the velocities of the stars, causing an overall delay in the evolution of the clusters and in the runaway growth of a massive star at the center. The population of binary stars is lower due to the increased kinetic energy of the stars, initially reducing the number of stellar collisions, and we show that relaxation processes are also affected. Despite these effects, the external potential enhances the mass of the merger product by a factor $\sim$2 if the collisions are maintained for long times.
- [19] arXiv:2005.07824 [pdf, other]
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Title: Effects of self-gravity of the accretion disk around rapidly rotating black hole in long GRBsComments: 4 pages, 1 figure, Acta Physica Polonica B Proceedings Supplement, Vol. 13 (2020), No.2Journal-ref: Acta Physica Polonica B Proceedings Supplement, Received January 20, 2020Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
We prescribe a method to study the effects of self-gravity of accretion disk around a black hole associated with long Gamma Ray Bursts (GRBs) in an evolving background Kerr metric. This is an extension to our previous work where we presented possible constraints for the final masses and spins of these astrophysical black holes. Incorporating the self-force of the accreting cloud around the black hole is a very important aspect due to the transient nature of the event, in which a huge amount of mass is accreted and changes the fundamental black hole parameters i.e. its mass and spin, during the process. Understanding of the GRBs engine is important because they are possible sources of high-energy particles and gravitational waves as most of the energy released from the dynamical evolution is in the form of gravitational radiation. Here, we describe the analytical framework we developed to employ in our numerical model. The numerical studies are planned for the future work.
- [20] arXiv:2005.07831 [pdf]
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Title: Science Merit Function for the KEPLER MissionAuthors: William J. Borucki (NASA Ames Research Center)Comments: 32 pages 11 figures submitted to SPIE Astronomical Telescopes, Instruments and SystemsSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Earth and Planetary Astrophysics (astro-ph.EP)
The Kepler Mission was a NASA Discovery-class mission designed to continuously monitor the brightness of at least 100,000 stars to determine the frequency of Earth-size and larger planets orbiting other stars. Once the Kepler proposal was chosen for a flight opportunity, it was necessary to optimize the design to accomplish the ambitious goals specified in the proposal and still stay within the available resources. To maximize the science return from the mission, a merit function (MF) was constructed that relates the science value (as determined by the PI and the Science Team) to the chosen mission characteristics and to models of the planetary and stellar systems. This MF served several purposes; prediction of the science results of the proposed mission, effects of varying the values of the mission parameters to increase the science product or to reduce the mission costs, and assessment of risks. The Merit Function was also valuable for the purposes of advocating the Mission by illustrating its expected capability. Later, it was used to keep management informed of the changing mission capability as trade-offs and mission down-sizing occurred.
The MF consisted of models of the stellar environment, assumed exoplanet characteristics and distributions, parameter values for the mission point-design, and equations that related the science value to the predicted number and distributions of detected exoplanets. A description of the MF model and representative results are presented. - [21] arXiv:2005.07864 [pdf, other]
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Title: The backbone-residual model. Accurately characterising the instrumental profile of a fibre-fed echelle spectrographAuthors: Zhibo Hao, Huiqi Ye, Jian Han, Liang Tang, Yang Zhai, Dong Xiao, Yongtian Zhu, Kai Zhang, Liang Wang, Gang Zhao, Fei Zhao, Huijuan Wang, Jie Zheng, Yujuan Liu, Jiaqi Wang, Ruyi Wei, Qiangqiang YanComments: 15 pages, 14 figures. Submitted to A&ASubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
Context: Instrumental profile (IP) is the basic property of a spectrograph. Accurate IP characterisation is the prerequisite of accurate wavelength solution. It also facilitates new spectral acquisition methods such as the forward modeling and deconvolution. Aims: We investigate an IP modeling method for the fibre-fed echelle spectrograph with the emission lines of the ThAr lamp, and explore the method to evaluate the accuracy of IP characterisation. Methods: The backbone-residual (BR) model is put forward and tested on the fibre-fed High Resolution Spectrograph (HRS) at the Chinese Xinglong 2.16-m Telescope, which is the sum of the backbone function and the residual function. The backbone function is a bell-shaped function to describe the main component and the spatial variation of IP. The residual function, which is expressed as the cubic spline function, accounts for the difference between the bell-shaped function and the actual IP. The method of evaluating the accuracy of IP characterisation is based on the spectral reconstruction and Monte Carlo simulation. Results: The IP of HRS is characterised with the BR model, and the accuracy of the characterised IP reaches 0.006 of the peak value of the backbone function. This result demonstrates that the accurate IP characterisation has been achieved on HRS with the BR model, and the BR model is an excellent choice for accurate IP characterisation of fibre-fed echelle spectrographs.
- [22] arXiv:2005.07888 [pdf, ps, other]
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Title: Orbital Modulation of Gamma Rays from PSR~J2339$-$0533Authors: Hongjun An (1), Roger W. Romani (2), Matthew Kerr (3) (Fermi-LAT Collaboration) ((1) Department of Astronomy and Space Science, Chungbuk National University, Cheongju, 28644, Republic of Korea, (2) Department of Physics/KIPAC, Stanford University, Stanford, CA 94305-4060, USA, (3) Space Science Division, Naval Research Laboratory, Washington, DC 20375-5352, USA)Comments: 11 pages, 7 figures. Accepted for publication in ApJSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
We report on orbital modulation of the 100-600 MeV gamma-ray emission of the $P_{\rm B}=4.6$ hr millisecond pulsar binary PSR J2339$-$0533 using 11 yr of Fermi Large Area Telescope data. The modulation has high significance (chance probability $p\approx 10^{-7}$), is approximately sinusoidal, peaks near pulsar superior conjunction, and is detected only in the low-energy 100-600 MeV band. The modulation is confined to the on-pulse interval, suggesting that the variation is in the 2.9-ms pulsed signal itself. This contrasts with the few other known systems exhibiting GeV orbital modulations, as these are unpulsed and generally associated with beamed emission from an intrabinary shock. The origin of the modulated pulsed signal is not yet clear, although we describe several scenarios, including Compton upscattering of photons from the heated companion. This would require high coherence in the striped pulsar wind.
- [23] arXiv:2005.07889 [pdf, other]
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Title: Science with the TianQin Observatory: Preliminary Results on Galactic Double White Dwarf BinariesAuthors: Shun-Jia Huang, Yi-Ming Hu, Valeriya Korol, Peng-Cheng Li, Zheng-Cheng Liang, Yang Lu, Hai-Tian Wang, Shenghua Yu, Jianwei MeiComments: 20 pages, 7 figuresSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc)
We explore the prospects of detecting of Galactic double white dwarf (DWD) binaries with the space-based gravitational wave (GW) observatory TianQin. In this work we analyse both a sample of currently known and a realistic synthetic population of DWDs to assess the number of guaranteed detections and the full capacity of the mission. We find that TianQin can detect 12 out of $\sim100$ known DWDs; GW signals of these binaries can be modelled in detail ahead of the mission launch, and therefore they can be used as verification sources. Besides we estimate that TianQin has potential to detect as many as $10^4$ DWDs in the Milky Way. TianQin is expected to measure their orbital periods and amplitudes with accuracy of $\sim10^{-7}$ and $\sim0.2$ respectively, and to localize on the sky a large fraction (39%) of the detected population to better than 1 deg$^2$. We conclude that TianQin has the potential to significantly advance our knowledge on Galactic DWDs by increasing the sample up to 2 orders of magnitude, and will allow their multi-messenger studies in combination with electromagnetic telescopes. We also test the possibilities of different configuration of TianQin: 1) the same mission with a different orientation, 2) two perpendicular constellations combined into a network, and 3) the combination of the network with the ESA-lead Laser Interferometer Space Antenna. We find that the network of detectors boosts the accuracy on the measurement of source parameters by $1-2$ orders of magnitude, with the improvement on sky localization being the most significant.
- [24] arXiv:2005.07921 [pdf, other]
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Title: Evolutionary and hydrodynamic models of short--period CepheidsAuthors: Yu.A. FadeyevComments: 15 pages, 5 figures, accepted to Astronomy LettersSubjects: Solar and Stellar Astrophysics (astro-ph.SR)
The evolutionary calculations for population I stars with masses on the main sequence 5 M_\odot <= M_0 <= 6.1 M_\odot and initial fractional abundances of helium Y_0=0.28 and heavier elements Z_0=0.02 were carried out to the stage of central helium exhaustion. Selected core helium--burning models were used as initial conditions for solution of the equations of hydrodynamics and time--dependent convection describing radial pulsations of Cepheids. In the Hertzsprung--Russel diagram the evolutionary tracks are shown to cross the red edge of the instability strip for M_0 > 5.1M_\odot. The grid of hydrodynamic models of core helium--burning Cepheids on the stages of the second and the third crossings of the instability strip was computed. The pulsation period \Pi and the rate of period change \dot\Pi were determined as a continuous function of star age for each evolutionary sequence of first--overtone pulsators. Results of calculations agree with observational estimates of \dot\Pi recently obtained for the short--period Cepheids V532 Cyg, BG Cru and RT Aur.
- [25] arXiv:2005.07929 [pdf]
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Title: Thermodynamics Interpretation of Electron Density and Temperature Description in the Solar CoronaSubjects: Solar and Stellar Astrophysics (astro-ph.SR)
We reach a thermodynamic interpretation of CODET model and its prediction to electrons density and temperature grounded on the physics of hydro magnetism in global equilibrium. The thermodynamic interpretation finds consistency with the model with a magneto-matter medium that is diamagnetic, in the context of ideal magnetohydrodynamics (MHD). It is further noticed that the CODET predicts a polytropic anomalous index for the electron gas of the Sun's corona. It is shown that this unusual characteristic is consistent with assuming that the low quiescent solar corona is a magneto-matter state which possesses an underlying structure that was earlier described to explain the 2-D adsorption process by a surface of a solid of molecules of a gas at a given temperature and pressure by Langmuir. In our case, it is assumed that we are in the presence of a 3-D similar coalescence process, i.e. a Langmuir amorphous lattice in thermodynamic equilibrium. In this way, constitutive properties of the medium magnetic permeability, the non-dispersive acoustic speed, the expected equilibration time for the 1.1 to 1.3$R_{\odot}$, and energy density are determined quantitatively for most of the quiescent corona in a near solar minimum that extends for several months from 2008 to 2009.
- [26] arXiv:2005.07931 [pdf, other]
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Title: A framework for the next generation of stationary cosmological modelsAuthors: Yves-Henri SanejouandComments: 13 pages, 5 figuresSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
According to a generic tired-light hypothesis found consistent with H(z) data, the density number of galaxies has been nearly constant over the last 10 Gyr at least, the density number of star-forming galaxies, as probed by sources of gamma-ray bursts, being constant as well, meaning that, as far as galaxies are concerned, the Universe has been stationary. On the other hand, an analysis of the luminosity distances of quasars and supernovae Ia shows that the Universe is far from being as transparent as assumed nowadays, the photon lifetime along the line-of-sight being one third of the Hubble time.
- [27] arXiv:2005.07933 [pdf, ps, other]
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Title: Triggered high-mass star formation in the HII region W28A2: A cloud-cloud collision scenarioAuthors: Katsuhiro Hayashi, Satoshi Yoshiike, Rei Enokiya, Shinji Fujita, Rin Yamada, Hidetoshi Sano, Kazufumi Torii, Mikito Kohno, Atsushi Nishimura, Akio Ohama, Hiroaki Yamamoto, Kengo Tachihara, Graeme Wong, Nigel Maxted, Catherine Braiding, Gavin Rowell, Michael Burton, Yasuo FukuiComments: 26 pages, 16 figures, Accepted for publication in PASJSubjects: Astrophysics of Galaxies (astro-ph.GA)
We report on a study of the high-mass star formation in the the HII region W28A2 by investigating the molecular clouds extended over ~5-10 pc from the exciting stars using the 12CO and 13CO (J=1-0) and 12CO (J=2-1) data taken by the NANTEN2 and Mopra observations. These molecular clouds consist of three velocity components with the CO intensity peaks at V_LSR ~ -4 km s$^{-1}$, 9 km s$^{-1}$ and 16 km s$^{-1}$. The highest CO intensity is detected at V_LSR ~ 9 km s$^{-1}$, where the high-mass stars with the spectral types of O6.5-B0.5 are embedded. We found bridging features connecting these clouds toward the directions of the exciting sources. Comparisons of the gas distributions with the radio continuum emission and 8 um infrared emission show spatial coincidence/anti-coincidence, suggesting physical associations between the gas and the exciting sources. The 12CO J=2-1 to 1-0 intensity ratio shows a high value (> 0.8) toward the exciting sources for the -4 km s$^{-1}$ and +9 km s$^{-1}$ clouds, possibly due to heating by the high-mass stars, whereas the intensity ratio at the CO intensity peak (V_LSR ~ 9 km s$^{-1}$) lowers down to ~0.6, suggesting self absorption by the dense gas in the near side of the +9 km s$^{-1}$ cloud. We found partly complementary gas distributions between the -4 km s$^{-1}$ and +9 km s$^{-1}$ clouds, and the -4 km s$^{-1}$ and +16 km s$^{-1}$ clouds. The exciting sources are located toward the overlapping region in the -4 km s$^{-1}$ and +9 km s$^{-1}$ clouds. Similar gas properties are found in the Galactic massive star clusters, RCW 38 and NGC 6334, where an early stage of cloud collision to trigger the star formation is suggested. Based on these results, we discuss a possibility of the formation of high-mass stars in the W28A2 region triggered by the cloud-cloud collision.
- [28] arXiv:2005.07951 [pdf, other]
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Title: Erosion of planetesimals by gas flowSubjects: Earth and Planetary Astrophysics (astro-ph.EP)
The first stages of planet formation take place in protoplanetary disks that are largely made up of gas. Understanding how the gas affects planetesimals in the protoplanetary disk is therefore essential. In this paper, we discuss whether or not gas flow can erode planetesimals. We estimate how much shear stress is exerted onto the planetesimal surface by the gas as a function of disk and planetesimal properties. To determine whether erosion can take place, we compare this with previous measurements of the critical stress that a pebble-pile planetesimal can withstand before erosion begins. If erosion takes place, we estimate the erosion time of the affected planetesimals. We also illustrate our estimates with two-dimensional numerical simulations of flows around planetesimals using the lattice Boltzmann method. We find that the wall shear stress can overcome the critical stress of planetesimals in an eccentric orbit within the innermost regions of the disk. The high eccentricities needed to reach erosive stresses could be the result of shepherding by migrating planets. We also find that if a planetesimal erodes, it does so on short timescales. For planetesimals residing outside of $1 \ \rm{au}$, we find that they are mainly safe from erosion, even in the case of highly eccentric orbits.
- [29] arXiv:2005.07953 [pdf, ps, other]
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Title: An Observational Test of Solar Plasma Heating by Magnetic Flux CancellationAuthors: Sung-Hong ParkComments: 17 pages, 6 figures, accepted for publication in ApJSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Space Physics (physics.space-ph)
Recent observations suggest that magnetic flux cancellation may play a crucial role to heat the Sun's upper atmosphere (chromosphere, transition region, corona). Here, we intended to validate an analytic model for magnetic reconnection and consequent coronal heating, driven by a pair of converging and cancelling magnetic flux sources of opposite polarities. For this test, we analyzed photospheric magnetic field and multi-wavelength UV/EUV observations of a small-scale flux cancellation event in a quiet-Sun internetwork region over a target interval of 5.2 hr. The observed cancellation event exhibits a converging motion of two opposite-polarity magnetic patches on the photosphere and red-shifted Doppler velocities (downflows) therein consistently over the target interval, with a decrease in magnetic flux of both polarities at a rate of 10$^{15}$ Mx s$^{-1}$. Several impulsive EUV brightenings, with DEM values peaked at 1.6-2.0 MK, are also observed in the shape of arcades with their two footpoints anchored in the two patches. The rate of magnetic energy released as heat at the flux cancellation region is estimated to be in the range of (0.2-1)$\times$10$^{24}$ erg s$^{-1}$ over the target interval, which can satisfy the requirement of previously reported heating rates for the quiet-Sun corona. Finally, both short-term (a few to several tens of minutes) variations and long-term (a few hours) trends in the magnetic energy release rate are clearly shown in the estimated rate of radiative energy loss of electrons at temperatures above 2.0 MK. All these observational findings support the validity of the investigated reconnection model for plasma heating in the upper solar atmosphere by flux cancellation.
- [30] arXiv:2005.07958 [pdf, other]
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Title: Detection of Small Flares from the Crab Nebula with Fermi-LATComments: 18 pages, 9 figures, accepted for publication in ApJSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
Gamma radiation from the Crab pulsar wind nebula (PWN) shows significant variability at $\sim100$ MeV energies, recently revealed with spaceborne gamma-ray telescopes. Here we report the results of a systematic search for gamma-ray flares using a 7.4-year data set acquired with the Fermi Large Area Telescope. Analyzing the off-pulse phases of the Crab pulsar, we found seven previously unreported low-intensity flares ("small flares"). The "small flares'' originate from the variable synchrotron component of the Crab PWN and show clearly different features from the steady component of the Crab PWN emission. They are characterized by larger fluxes and harder photon indices, similar to previously reported flares. These flares show day-scale time variability and imply a strong magnetic field of $B_{\rm min}\approx 1~\mathrm{mG}$ at the site of the gamma-ray production. This result seems to be inconsistent with the typical values revealed with modeling of the non-thermal emission from the nebula. The detection of the "small flares'' gives a hint of production of gamma rays above $100$ MeV in a part of the nebula with properties which are different from the main emitters, e.g., due to bulk relativistic motion.
- [31] arXiv:2005.07964 [pdf, other]
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Title: Parity in Planck full-mission CMB temperature mapsComments: 12 pages, 5 figuresSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
In the standard model of cosmology, Cosmic Microwave Background (CMB) sky is expected to show no symmetry preferences. Following our previous studies, we explore the presence of any particular parity preference in the latest full-mission CMB temperature maps from ESA's Planck probe. Specifically, in this work, we will probe (a)symmetry in power between even and odd multipoles of CMB via it's angular power spectrum from Planck 2015 data. Further we also assess any specific preference for mirror parity (a)symmetry, by analysing the power contained in $l+m$=even or odd mode combinations.
- [32] arXiv:2005.07971 [pdf, ps, other]
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Title: X-ray emission evolution of the Galactic ultra-luminous X-ray pulsar Swift J0243.6+6124 during the 2017-2018 outburst observed by the MAXI GSCAuthors: Mutsumi Sugizaki, Motoki Oeda, Nobuyuki Kawai, Tatehiro Mihara, Kazuo Makishima, Motoki NakajimaComments: 19 pages, 13 figures, accepted for publication in ApJSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
This paper reports on the X-ray emission evolution of the ultra-luminous Galactic X-ray pulsar, Swift J0243.6+6124, during the 2017-2018 giant outburst observed by the MAXI GSC. The 2-30 keV light curve and the energy spectra confirm that the luminosity $L_\mathrm{X}$ reached $2.5\times 10^{39}$ erg s$^{-1}$, 10 times higher than the Eddington limit. When the source was luminous with $L_\mathrm{X}\gtrsim 0.9\times 10^{38}$ erg s$^{-1}$, it exhibited a negative correlation on a hardness-intensity diagram. However, two hardness ratios, a soft color ($=$ 4-10 keV / 2-4 keV) and a hard color ($=$ 10-20 keV / 4-10 keV), showed somewhat different behavior across a characteristic luminosity of $L_\mathrm{c}\simeq 5\times 10^{38}$ erg s$^{-1}$. The soft color changed more than the hard color when $L_\mathrm{X} < L_\mathrm{c}$, whereas the opposite was observed above $L_\mathrm{c}$. The spectral change above $L_\mathrm{c}$ was represented by a broad enhanced feature at $\sim 6$ keV. The pulse profiles made a transition from a single-peak to a double-peak one as the source brightened across $L_\mathrm{c}$. These spectral and pulse-shape properties can be interpreted by a scenario that the accretion columns on the neutron star surface, producing the Comptonized X-ray emission, gradually became taller as $L_\mathrm{X}$ increased. The broad 6 keV enhancement could be a result of cyclotron-resonance absorption at $\sim 10$ keV, corresponding to a surface magnetic field $B_\mathrm{s}\simeq 1.1\times 10^{12}$ G. The spin-frequency derivatives calculated with the Fermi GBM data showed a smooth correlation with $L_\mathrm{X}$ up to the outburst peak, and its linear coefficient is comparable to those of X-ray binary pulsars whose $B_\mathrm{s}$ are $(1-8)\times 10^{12}$ G. These results suggest that $B_\mathrm{s}$ of Swift J0243.6$+$6124 is a few times $10^{12}$ G.
- [33] arXiv:2005.07993 [pdf, other]
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Title: Investigation of energy spectrum and chemical composition of primary cosmic rays in 1-100 PeV energy range with a UAV-borne installationAuthors: D. Chernov, E. Bonvech, M. Finger Jr, M. Finger, V. Galkin, V. Ivanov, D. Podgrudkov, T. Roganova, I. VaimanComments: Procs. of the Instrumentation for Colliding Beam Physics Conference (INSTR20), 24--28 February 2020, Novosibirsk, Russia. Contains 11 pages, 7 figures. Submitted to JINSTSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); High Energy Astrophysical Phenomena (astro-ph.HE)
A new project is developed with the implementation of a relatively new method of studying the primary cosmic ray -- the registration of extensive air showers' optical Vavilov-Cherenkov radiation (Cherenkov light) reflected from the snow surface. The aim of the project is the study of the cosmic ray mass composition in the energy range of 1-100 PeV by detecting the reflected extensive air showers' Cherenkov light. Silicon photomultipliers are planned to be used as the main photosensitive element of the detector and an unmanned aerial vehicle will is planned to lift the measuring equipment over the snow-covered ground.
- [34] arXiv:2005.08029 [pdf, other]
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Title: Windowing Artifacts Likely Account for Recent Claimed Detection of Oscillating Cosmic Scale FactorSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Astrophysical Phenomena (astro-ph.HE)
Using the Pantheon data set of Type Ia supernovae, \cite{Ringermacher2020} (R20 henceforth) report a $~2\sigma$ detection of oscillations in the expansion history of the universe. Applying the R20 methodology to simulated Pantheon data, we determine that these oscillations likely arise from analysis artifacts. The uneven spacing of Type Ia supernovae in redshift space and the complicated analysis method of R20 impose a structured throughput function. When analyzed with the R20 prescription, about $11\%$ of artificial $\Lambda$CDM data sets produce a stronger oscillatory signal than the actual Pantheon data. The study conducted by R20 is a wholly worthwhile endeavor. However, we believe that the detected oscillations are not due to an oscillating cosmic scale factor and are instead artifacts of the data processing. Our results underscore the importance of understanding the false `signals' that can be introduced by complicated data analyses.
- [35] arXiv:2005.08049 [pdf, other]
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Title: Modeling Stochastic Variability in Multi-Band Time Series DataSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Methodology (stat.ME)
In preparation for the era of the time-domain astronomy with upcoming large-scale surveys, we propose a state-space representation of a multivariate damped random walk process as a tool to analyze irregularly-spaced multi-filter light curves with heteroscedastic measurement errors. We adopt a computationally efficient and scalable Kalman-filtering approach to evaluate the likelihood function, leading to maximum $O(k^3n)$ complexity, where $k$ is the number of available bands and $n$ is the number of unique observation times across the $k$ bands. This is a significant computational advantage over a commonly used univariate Gaussian process that can stack up all multi-band light curves in one vector with maximum $O(k^3n^3)$ complexity. Using such efficient likelihood computation, we provide both maximum likelihood estimates and Bayesian posterior samples of the model parameters. Three numerical illustrations are presented; (i) analyzing simulated five-band light curves for a comparison with independent single-band fits; (ii) analyzing five-band light curves of a quasar obtained from the Sloan Digital Sky Survey (SDSS) Stripe~82 to estimate the short-term variability and timescale; (iii) analyzing gravitationally lensed $g$- and $r$-band light curves of Q0957+561 to infer the time delay. Two R packages, Rdrw and timedelay, are publicly available to fit the proposed models.
- [36] arXiv:2005.08112 [pdf, other]
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Title: Detectability of radio afterglows from Fast Radio Bursts produced by Binary Neutron Star MergersComments: 7 pages, 3 figures. Submitted to MNRASSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
Binary neutron star (BNS) mergers are one of the proposed origins for both repeating and non-repeating fast radio bursts (FRBs), which associates FRBs with gravitational waves and short gamma-ray bursts (GRBs). In this work, we explore detectability of radio counterparts to an FRB by calculating the radio afterglow flux powered by the two components: a relativistic jet and a slower isotropic ejecta from a BNS merger. Detection probability of a radio afterglow for a FRB is calculated as a function of the source redshift, observing time, and flux sensitivity, assuming that FRBs are not strongly beamed. The model parameter distributions inferred from short GRB afterglows are adopted. We find that the detection probability for an FRB at $z=0.5$ is 3.7 and 4.1% for the jet and isotropic components, respectively, when observed at the timing of their peak flux ($\sim$10 days and 1 year) with a typical sensitivity of 10 $\mu$Jy. The probability increases to 10 and 14%, respectively, with $\sim$1 $\mu$Jy sensitivity achievable with future facilities (e.g. SKA). In particular for the repeating FRB 180916.J0158+65, we find a high chance of detection (60% at 10 $\mu$Jy sensitivity) for the isotropic component that would peak around $\sim$10 years after the merger, as a natural consequence of its close distance ($z=0.03$). Therefore a long term radio monitoring of persistent radio emission for this object is important. The detection probability is similar for the jet component, though the peak time ($\sim$200 days) has likely already passed for this FRB.
- [37] arXiv:2005.08126 [pdf, other]
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Title: Inferring astrophysical X-ray polarization with deep learningComments: Accepted to International Conference on Learning Representations (ICLR) 2020 Workshop: Fundamental Science in the Era of AISubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); High Energy Astrophysical Phenomena (astro-ph.HE); Machine Learning (cs.LG)
We investigate the use of deep learning in the context of X-ray polarization detection from astrophysical sources as will be observed by the Imaging X-ray Polarimetry Explorer (IXPE), a future NASA selected space-based mission expected to be operative in 2021. In particular, we propose two models that can be used to estimate the impact point as well as the polarization direction of the incoming radiation. The results obtained show that data-driven approaches depict a promising alternative to the existing analytical approaches. We also discuss problems and challenges to be addressed in the near future.
- [38] arXiv:2005.08161 [pdf, other]
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Title: A geometrical interpretation for the properties of multiband optical variability of the blazar S5 0716+714Authors: Marina S. ButuzovaComments: 31 pages, 16 figures, 3 tablesSubjects: Astrophysics of Galaxies (astro-ph.GA); High Energy Astrophysical Phenomena (astro-ph.HE)
We present the results of multiband observations of the blazar S5 0716+714 intra-night variability performed during 23 nights in the period from 04.2014 through 04.2015. The bluer-when-brighter trend is detected in both intra- and inter-night data. We assume that the jet component crossing the region where the medium becomes transparent to the optical radiation forms almost all optical emission of S5 0716+714. Deviations of some parts of the component from the general trajectory of the component can cause the Doppler factor of these parts to increase. Various maximum Doppler factors achieved by these parts of the component and different volumes occupied by them with the concave synchrotron self-absorption spectrum result in both the observed various color index behavior in variability and explain the absence of dependence of the bluer-when-brighter behavior on the object magnitude. We estimated spectral maximum frequencies from intra- and inter-night data. Both the agreement of the obtained values of $\nu_{\text{m}}\approx( 1.0-2.5)\cdot10^{14}$ GHz and the fact that $\nu_{\text{m}}$ is less than the frequencies of optical observations confirm our assumption about the nature of the blazar S5 0716+714 region radiating in the optical range.
- [39] arXiv:2005.08163 [pdf, other]
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Title: High Speed Source Localization in Searches for Gravitational Waves from Compact Object CollisionsSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
Multi-messenger astronomy is of great interest since the success of the electromagnetic follow up of the neutron star merger GW170817. However, the information that was learned from GW170817 was limited by the long delay in finding the optical transient. Even in the best-case scenario, the current gravitational-wave source localization method is not sufficient for some frequency bands. Therefore, one needs a more rapid localization method even if it is less accurate. Building upon an Excess power method, we describe a new localization method for compact object collisions that produces posterior probability maps in only a few hundred milliseconds. Some accuracy is lost, with the searched sky areas being approximately $10$ times larger. We imagine this new technique playing a role in a hierarchical scheme were fast early location estimates are iteratively improved upon as better analyses complete on longer time scales.
- [40] arXiv:2005.08173 [pdf, ps, other]
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Title: Infrared Dark Clouds and high-mass star formation activity in Galactic Molecular CloudsAuthors: R. Retes-Romero (1,2), Y. D. Mayya (1), A. Luna (1), L. Carrasco (1) ((1) INAOE, Puebla, Mexico, (2) UPAEP, Puebla, Mexico)Comments: 9 pages. Accepted for publication in ApJSubjects: Astrophysics of Galaxies (astro-ph.GA)
Ever since their discovery, Infrared dark clouds (IRDCs) are generally considered to be the sites just at the onset of high-mass (HM) star formation. In recent years, it has been realized that not all IRDCs harbour HM Young Stellar Objects (YSOs). Only those IRDCs satisfying a certain mass-size criterion, or equivalently above a certain threshold density, are found to contain HMYSOs. In all cases, IRDCs provide ideal conditions for the formation of stellar clusters. In this paper, we study the massive stellar content of IRDCs to re-address the relation between IRDCs and HM star formation. For this purpose, we have identified all IRDCs associated to a sample of 12 Galactic molecular clouds (MCs). The selected MCs have been the target of a systematic search for YSOs in an earlier study. The catalogued positions of YSOs have been used to search all YSOs embedded in each identified IRDC. In total, we have found 834 YSOs in 128 IRDCs. The sample of IRDCs have mean surface densities of 319 Mo/pc2, mean mass of 1062 Mo, and a mass function power-law slope -1.8, which are similar to the corresponding properties for the full sample of IRDCs and resulting physical properties in previous studies. We find that all those IRDCs containing at least one intermediate to high-mass young star satisfy the often-used mass-size criterion for forming HM stars. However, not all IRDCs satisfying the mass-size criterion contain HM stars. We find that the often used mass-size criterion corresponds to 35% probability of an IRDC forming a massive star. Twenty five (20%) of the IRDCs are potential sites of stellar clusters of mass more than 100 Mo.
- [41] arXiv:2005.08197 [pdf, other]
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Title: Gas Kinematics of the Massive Protocluster G286.21+0.17 Revealed by ALMAComments: 26 pages, 17 figures, accepted by ApJJournal-ref: The Astrophysical Journal, Volume 894, 2020, Number 2, Page 87Subjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
We study the gas kinematics and dynamics of the massive protocluster G286.21+0.17 with the Atacama Large Millimeter/submillimeter Array using spectral lines of $C^{18}O$(2-1), $N_2D^+$(3-2), $DCO^+$(3-2) and $DCN$(3-2). On the parsec clump scale, $C^{18}O$ emission appears highly filamentary around the systemic velocity. $N_2D^+$ and $DCO^+$ are more closely associated with the dust continuum. $DCN$ is strongly concentrated towards the protocluster center, where no or only weak detection is seen for $N_2D^+$ and $DCO^+$, possibly due to this region being at a relatively evolved evolutionary stage. Spectra of 76 continuum defined dense cores, typically a few 1000 AU in size, are analysed to measure their centroid velocities and internal velocity dispersions. There are no statistically significant velocity offsets of the cores among the different dense gas tracers. Furthermore, the majority (71\%) of the dense cores have subthermal velocity offsets with respect to their surrounding, lower density $C^{18}O$ emitting gas. Within the uncertainties, the dense cores in G286 show internal kinematics that are consistent with being in virial equilibrium. On clumps scales, the core to core velocity dispersion is also similar to that required for virial equilibrium in the protocluster potential. However, the distribution in velocity of the cores is largely composed of two spatially distinct groups, which indicates that the dense molecular gas has not yet relaxed to virial equilibrium, perhaps due to there being recent/continuous infall into the system.
- [42] arXiv:2005.08198 [pdf, other]
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Title: Stellar Variability in a Forming Massive Star ClusterComments: 13 pages, 8 figures, accepted by ApJSubjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
We present a near-infrared (NIR) variability analysis for an 6\arcmin $\times$ 6\arcmin region, which encompasses the massive protocluster G286.21+0.17. The total sample comprises more than 5000 objects, of which 562 show signs of a circumstellar disk based on their infrared colors. The data includes HST observations taken in two epochs separated by 3 years in the F110W and F160W bands. 363 objects (7% of the sample) exhibit NIR variability at a significant level (Stetson index >1.7), and a higher variability fraction (14%) is found for the young stellar objects (YSOs) with disk excesses. We identified 4 high amplitude (>0.6 mag) variables seen in both NIR bands. Follow up and archival observations of the most variable object in this survey (G286.2032+0.1740) reveal a rising light curve over 8 years from 2011 to 2019, with a K band brightening of 3.5 mag. Overall the temporal behavior of G286.2032+0.1740 resembles that of typical FU Ori objects, however its pre-burst luminosity indicates it has a very low mass ($<0.12\:M_\odot$), making it an extreme case of an outburst event that is still ongoing.
- [43] arXiv:2005.08212 [pdf, other]
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Title: Science with the TianQin observatory: Preliminary result on extreme-mass-ratio inspiralsAuthors: Hui-Min Fan, Yi-Ming Hu, Enrico Barausse, Alberto Sesana, Jian-Dong Zhang, Xuefeng Zhang, Tie-Guang Zi, Jianwei MeiComments: 13 pages, 5 figuresSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc)
Systems consisting of a massive black hole (MBH) and a stellar-origin compact object (CO), known as extreme mass-ratio inspirals (EMRIs), are of great significance for space-based gravitational-wave detectors, as they will allow for testing gravitational theories in the strong field regime, and for checking the validity of the black hole no-hair theorem. In this work, we present a calculation of the EMRI rate and parameter estimation capabilities of the TianQin observatory, for various astrophysical models for these sources. We find that TianQin can observe EMRIs involving COs with mass of 10$M_\odot$ up to redshift $\sim2$. We also find that detections could reach tens or hundreds per year in the most optimistic astrophysical scenarios. Intrinsic parameters are expected to be recovered to within fractional errors of $\sim 10^{-6}$, while typical errors on the luminosity distance and sky localization are 10% and 10 deg$^2$, respectively. TianQin observation of EMRIs can also constrain possible deviations from the Kerr quadrupole moment to within fractional errors $\lesssim10^{-4}$. We also find that a network of multiple detectors would allow for improvements in both detection rates (by a factor $\sim 1.5$--$3$) and in parameter estimation precision (20-fold improvement for the sky localization and 5-fold improvement for the other parameters.)
- [44] arXiv:2005.08250 [pdf, ps, other]
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Title: What did the seahorse swallow? APEX 170 GHz observations of the chemical conditions in the Seahorse infrared dark cloudAuthors: Oskari MiettinenComments: 23 pages (incl. an appendix), 13 figures, 7 tables, accepted for publication in A&A, abstract abridged for arXivSubjects: Astrophysics of Galaxies (astro-ph.GA)
We used the APEX telescope to observe spectral lines occurring at about 170 GHz frequency towards 14 positions along the full extent of the filamentary Seahorse infrared dark cloud. Six spectral line transitions were detected ($\geq3\sigma$) altogether, namely, SO$(N_J=4_4-3_3)$, H$^{13}$CN$(J=2-1)$, H$^{13}$CO$^+(J=2-1)$, SiO$(J=4-3)$, HN$^{13}$C$(J=2-1)$, and C$_2$H$(N=2-1)$. While SO, H$^{13}$CO$^+$, and HN$^{13}$C were detected in every source, the detection rates for C$_2$H and H$^{13}$CN were 92.9% and 85.7%, respectively. Only one source (SMM 3) showed detectable SiO emission (7.1% detection rate). Three clumps (SMM 5, 6, and 7) showed the SO, H$^{13}$CN, H$^{13}$CO$^+$, HN$^{13}$C, and C$_2$H lines in absorption. We found three positive correlations among the derived molecular abundances, of which those between C$_2$H and HN$^{13}$C and HN$^{13}$C and H$^{13}$CO$^+$ are the most significant (correlation coefficient $r\simeq0.9$). The statistically most significant evolutionary trends we uncovered are the drops in the C$_2$H abundance and in the $[{\rm HN^{13}C}]/[{\rm H^{13}CN}]$ ratio as the clump evolves from an IR dark stage to an IR bright stage and then to an HII region. The correlations we found between the different molecular abundances can be understood as arising from the gas-phase electron (ionisation degree) and atomic carbon abundances. The [C$_2$H] evolutionary indicator we found is in agreement with previous studies, and can be explained by the conversion of C$_2$H to other species (e.g. CO) when the clump temperature rises, especially after the ignition of a hot molecular core in the clump. The decrease of $[{\rm HN^{13}C}]/[{\rm H^{13}CN}]$ as the clump evolves is also likely to reflect the increase in the clump temperature, which leads to an enhanced formation of HCN and its $^{13}$C isotopologue.
- [45] arXiv:2005.08252 [pdf, ps, other]
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Title: Gravitational Focusing of Low-Velocity Dark Matter on the Earth's SurfaceAuthors: Yoshiaki SofueComments: To appear in Galaxies: special issue on Debate on the Dark Matter; 8 pages, 7 figuresSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); Astrophysics of Galaxies (astro-ph.GA)
We show that the Earth acts as a high-efficiency gravitational collector of low-velocity flow of dark matter (DM). The focal point appears on the Earth's surface, when the DM flow speed is about 17 km s$^{-1}$ with respect to the geo-center. We discuss diurnal modulation of the local DM density influenced by the Earth's gravity. We also touch upon similar effects on galactic and solar system objects.
- [46] arXiv:2005.08270 [pdf, ps, other]
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Title: Distances to the Supernova Remnants in the Inner DiskAuthors: Shu Wang, Chengyu Zhang, Biwei Jiang, He Zhao, Bingqiu Chen, Xiaodian Chen, Jian Gao, Jifeng LiuComments: 31 pages, 25 figures, 2 tables, accepted for publication in A&ASubjects: Astrophysics of Galaxies (astro-ph.GA)
Distance measurements of supernova remnants (SNRs) are essential and important. Accurate estimates of physical size, dust masses, and some other properties of SNRs depend critically on accurate distance measurements. However, the determination of SNR distances is still a tough task. Red clump stars (RCs) have a long history been used as standard candles. In this work, we take RCs as tracers to determine the distances to a large group of SNRs in the inner disk. We first select RC stars based on the near-infrared (IR) color-magnitude diagram (CMD). Then, the distance to and extinction of RC stars are calculated. To extend the measurable range of distance, we combine near-IR photometric data from the 2MASS survey with the deeper UKIDSS and VVV surveys. With the help of the Gaia parallaxes, we also remove contaminants including dwarfs and giants. Because an SN explosion compresses the surrounding interstellar medium, the SNR region would become denser and exhibit higher extinction than the surroundings. The distance of a SNR is then recognized by the position where the extinction and its gradient is higher than that of the ambient medium. A total of 63 SNRs' distances in the Galactic inner disk are determined and divided into three Levels A, B, and C with decreasing reliability. The distances to 43 SNRs are well determined with reliability A or B. The diameters and dust masses of SNRs are estimated with the obtained distance and extinction.
- [47] arXiv:2005.08317 [pdf, other]
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Title: C18O, 13CO, and 12CO abundances and excitation temperatures in the Orion B molecular cloud: An analysis of the precision achievable when modeling spectral line within the Local Thermodynamic Equilibrium approximationAuthors: Antoine Roueff (1), Maryvonne Gerin (2), Pierre Gratier (3), Francois Levrier (4), Jerome Pety (5 and 2), Mathilde Gaudel (2), Javier R. Goicoechea (6), Jan H. Orkisz (7), Victor de Souza Magalhaes (5), Maxime Vono (8), Sebastien Bardeau (5), Emeric Bron (9), Jocelyn Chanussot (10), Pierre Chainais (11), Viviana V. Guzman (12), Annie Hughes (13), Jouni Kainulainen (7), David Languignon (9), Jacques Le Bourlot (9), Franck Le Petit (9), Harvey S. Liszt (14), Antoine Marchal (15), Marc-Antoine Miville-Deschenes (16), Nicolas Peretto (17), Evelyne Roueff (9), Albrecht Sievers (5) ((1) Aix Marseille Univ, CNRS, Centrale Marseille, Institut Fresnel, Marseille, France, (2) LERMA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universites, Paris, France, (3) Laboratoire d'Astrophysique de Bordeaux, Univ. Bordeaux, CNRS, Pessac, France, (4) Laboratoire de Physique de l'Ecole normale superieure, ENS, Universite PSL, CNRS, Sorbonne Universite, Universite de Paris, Sorbonne Paris Cite, Paris, France, (5) IRAM, Saint Martin d'Heres, France, (6) Instituto de Fisica Fundamental (CSIC), Madrid, Spain, (7) Chalmers University of Technology, Department of Space, Earth and Environment, Gothenburg, Sweden, (8) University of Toulouse, IRIT/INP-ENSEEIHT, CNRS, Toulouse, France, (9) LERMA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universites, Meudon, France, (10) Univ. Grenoble Alpes, Inria, CNRS, Grenoble INP, GIPSA-Lab, Grenoble, France, (11) Univ. Lille, CNRS, Centrale Lille, UMR 9189 - CRIStAL, Villeneuve d'Ascq, France, (12) Instituto de Astrofisica, Pontificia Universidad Catolica de Chile, Santiago, Chile, (13) Institut de Recherche en Astrophysique et Planetologie (IRAP), Universite Paul Sabatier, Toulouse, France, (14) National Radio Astronomy Observatory, Charlottesville, USA, (15) Canadian Institute for Theoretical Astrophysics, University of Toronto, Canada, (16) AIM, CEA, CNRS, Universite Paris-Saclay, Universite Paris Diderot, Sorbonne Paris Cite, Gif-sur-Yvette, France, (17) School of Physics and Astronomy, Cardiff University, Queen's buildings, Cardiff, UK)Comments: 27 pages, 23 PDF figures. Accepted for publication in A&A. Uses aa latex macroSubjects: Astrophysics of Galaxies (astro-ph.GA); Instrumentation and Methods for Astrophysics (astro-ph.IM)
CO isotopologue transitions are routinely observed in molecular clouds to probe the column density of the gas, the elemental ratios of carbon and oxygen, and to trace the kinematics of the environment. We aim at estimating the abundances, excitation temperatures, velocity field and velocity dispersions of the three main CO isotopologues towards a subset of the Orion B molecular cloud. We use the Cramer Rao Bound (CRB) technique to analyze and estimate the precision of the physical parameters in the framework of local-thermodynamic-equilibrium excitation and radiative transfer with an additive white Gaussian noise. We propose a maximum likelihood estimator to infer the physical conditions from the 1-0 and 2-1 transitions of CO isotopologues. Simulations show that this estimator is unbiased and efficient for a common range of excitation temperatures and column densities (Tex > 6 K, N > 1e14 - 1e15 cm-2). Contrary to the general assumptions, the different CO isotopologues have distinct excitation temperatures, and the line intensity ratios between different isotopologues do not accurately reflect the column density ratios. We find mean fractional abundances that are consistent with previous determinations towards other molecular clouds. However, significant local deviations are inferred, not only in regions exposed to UV radiation field but also in shielded regions. These deviations result from the competition between selective photodissociation, chemical fractionation, and depletion on grain surfaces. We observe that the velocity dispersion of the C18O emission is 10% smaller than that of 13CO. The substantial gain resulting from the simultaneous analysis of two different rotational transitions of the same species is rigorously quantified. The CRB technique is a promising avenue for analyzing the estimation of physical parameters from the fit of spectral lines.
- [48] arXiv:2005.08330 [pdf, other]
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Title: Formation of Giant Planet SatellitesComments: 31 pages, 12 figures, accepted for publication in ApJSubjects: Earth and Planetary Astrophysics (astro-ph.EP)
Recent analyses have shown that the concluding stages of giant planet formation are accompanied by the development of large-scale meridional flow of gas inside the planetary Hill sphere. This circulation feeds a circumplanetary disk that viscously expels gaseous material back into the parent nebula, maintaining the system in a quasi-steady state. Here we investigate the formation of natural satellites of Jupiter and Saturn within the framework of this newly outlined picture. We begin by considering the long-term evolution of solid material, and demonstrate that the circumplanetary disk can act as a global dust trap, where $s_{\bullet}\sim0.1-10\,$mm grains achieve a hydrodynamical equilibrium, facilitated by a balance between radial updraft and aerodynamic drag. This process leads to a gradual increase in the system's metallicity, and eventually culminates in the gravitational fragmentation of the outer regions of the solid sub-disk into $\mathcal{R}\sim100\,$km satellitesimals. Subsequently, satellite conglomeration ensues via pairwise collisions, but is terminated when disk-driven orbital migration removes the growing objects from the satellitesimal feeding zone. The resulting satellite formation cycle can repeat multiple times, until it is brought to an end by photo-evaporation of the parent nebula. Numerical simulations of the envisioned formation scenario yield satisfactory agreement between our model and the known properties of the Jovian and Saturnian moons.
- [49] arXiv:2005.08352 [pdf, ps, other]
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Title: A comparison of X-ray photon indices among the narrow and broad-line Seyfert 1 galaxiesComments: 21 pages, 12 figures, Accepted for publication in ApJSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA)
We present a detailed comparative systematic study using a sample of 221 Narrow-line Seyfert 1 (NLSy1) galaxies in comparison to a redshift matched sample of 154 Broad-line Seyfert 1 (BLSy1) galaxies based on their observations using ROSAT and/or XMM-Newton telescopes in soft X-ray band (0.1-2.0 keV). A homogeneous analysis is carried out to estimate their soft X-ray photon indices ($\Gamma^{s}_{X}$) and its correlations with other parameters of nuclear activities such as Eddington ratios (R$_\mathrm{Edd}$), bolometric luminosities (L$_\mathrm{bol}$), black hole masses (M$_\mathrm{BH}$) and the widths of the broad component of H$\beta$ lines (FWHM(H$\beta$)). In our analysis, we found clear evidence of the difference in the $\Gamma^{s}_{X}$ and R$_\mathrm{Edd}$ distributions among NLSy1 and BLSy1 galaxies, with steeper $\Gamma^{s}_{X}$ and higher R$_\mathrm{Edd}$ for the former. Such a difference also exists in the spectral indices distribution in hard X-ray ($\Gamma^{h}_{X}$), based on the analysis of 53 NLSy1 and 46 BLSy1 galaxies in the 2-10 keV energy band. The difference in R$_\mathrm{Edd}$ distributions does exist even after applying the average correction for the difference in the inclination angle of NLSy1 and BLSy1 galaxies. We also estimated R$_\mathrm{Edd}$, based on SED fitting of 34 NLSy1 and 30 BLSy1 galaxies over the 0.3-10 keV energy band and found that results are still consistent with R$_\mathrm{Edd}$ estimates based on the optical bolometric luminosity. Our analysis suggests that the higher R$_\mathrm{Edd}$ in NLSy1 is responsible for its steeper X-ray spectral slope compared to the BLSy1, consistent with the disc-corona model as proposed for the luminous AGNs.
- [50] arXiv:2005.08410 [pdf, other]
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Title: Bright X-ray and Radio Pulses from a Recently Reactivated MagnetarAuthors: Aaron B. Pearlman, Walid A. Majid, Thomas A. Prince, Paul S. Ray, Jonathon Kocz, Shinji Horiuchi, Charles J. Naudet, Tolga Güver, Teruaki Enoto, Zaven Arzoumanian, Keith C. Gendreau, Wynn C. G. HoComments: 54 pages, 8 figures, Submitted for publication in Nature AstronomySubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
Magnetars are young, rotating neutron stars that possess larger magnetic fields ($B$ $\approx$ $10^{13}$-$10^{15}$ G) and longer rotational periods ($P$ $\approx$ 1-12 s) than ordinary pulsars. In contrast to rotation-powered pulsars, magnetar emission is thought to be fueled by the evolution and decay of their powerful magnetic fields. They display highly variable radio and X-ray emission, but the processes responsible for this behavior remain a mystery. We report the discovery of bright, persistent individual X-ray pulses from XTE J1810-197, a transient radio magnetar, using the Neutron star Interior Composition Explorer (NICER) following its recent radio reactivation. Similar behavior has only been previously observed from a magnetar during short time periods following a giant flare. However, the X-ray pulses presented here were detected outside of a flaring state. They are less energetic and display temporal structure that differs from the impulsive X-ray events previously observed from the magnetar class, such as giant flares and short X-ray bursts. Our high frequency radio observations of the magnetar, carried out simultaneously with the X-ray observations, demonstrate that the relative alignment between the X-ray and radio pulses varies on rotational timescales. No correlation was found between the amplitudes or temporal structure of the X-ray and radio pulses. The magnetar's 8.3 GHz radio pulses displayed frequency structure, which was not observed in the pulses detected simultaneously at 31.9 GHz. Many of the radio pulses were also not detected simultaneously at both frequencies, which indicates that the underlying emission mechanism producing these pulses is not broadband. We find that the radio pulses from XTE J1810-197 share similar characteristics to radio bursts detected from fast radio burst (FRB) sources, some of which are now thought to be produced by active magnetars.
- [51] arXiv:2005.08462 [pdf, ps, other]
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Title: Probing Cosmic Rays with Fe K$α$ Line Structures Generated by Multiple Ionization ProcessAuthors: Hiromichi OkonComments: 6 pages, 4 figures Accepted for publication in Publications of the Astronomical Society of JapanSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
Supernova remnants (SNRs) have been regarded as major acceleration sites of Galactic cosmic rays. Recent X-ray studies revealed neutral Fe K$\alpha$ line emission from dense gas in the vicinity of some SNRs, which can be best interpreted as K-shell ionization of Fe atoms in the gas by sub-relativistic particles accelerated in the SNRs. In this Letter, we propose a novel method of constraining the composition of particles accelerated in SNRs, which is currently unknown. When energetic heavy ions collide with target atoms, their strong Coulomb field can easily cause simultaneous ejection of multiple inner-shell electrons of the target. This results in shifts in characteristic X-ray line energies, forming distinctive spectral structures. Detection of such structures in the neutral Fe K$\alpha$ line strongly supports the particle ionization scenario, and furthermore provides direct evidence of heavy ions in the accelerated particles. We construct a model for the Fe K$\alpha$ line structures by various projectile ions utilizing atomic-collision data.
- [52] arXiv:2005.08524 [pdf, other]
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Title: Time dependence of the flux of helium nuclei in cosmic rays measured by the PAMELA experiment between July 2006 and December 2009Authors: N. Marcelli, M. Boezio, A. Lenni, W. Menn, R. Munini, O. P. M. Aslam, D. Bisschoff, M. D. Ngobeni, M. S. Potgieter, O. Adriani, G. C. Barbarino, G. A. Bazilevskaya, R. Bellotti, E. A. Bogomolov, M. Bongi, V. Bonvicini, A. Bruno, F. Cafagna, D. Campana, P. Carlson, M. Casolino, G. Castellini, C. De Santis, A. M. Galper, S. V. Koldashov, S. Koldobskiy, A. N. Kvashnin, A. A. Leonov, V. V. Malakhov, L. Marcelli, M. Martucci, A. G. Mayorov, M. Mergè, E. Mocchiutti, A. Monaco, N. Mori, V. V. Mikhailov, G. Osteria, B. Panico, P. Papini, M. Pearce, P. Picozza, M. Ricci, S. B. Ricciarini, M. Simon, A. Sotgiu, R. Sparvoli, P. Spillantini, Y. I. Stozhkov, A. Vacchi, E. Vannuccini, G. I. Vasilyev, S. A. Voronov, Y. T. Yurkin, G. Zampa, N. ZampaJournal-ref: The Astrophysical Journal, Volume 893, Number 2, 2020Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); Space Physics (physics.space-ph)
Precise time-dependent measurements of the Z = 2 component in the cosmic radiation provide crucial information about the propagation of charged particles through the heliosphere. The PAMELA experiment, with its long flight duration (15th June 2006 - 23rd January 2016) and the low energy threshold (80 MeV/n) is an ideal detector for cosmic ray solar modulation studies. In this paper, the helium nuclei spectra measured by the PAMELA instrument from July 2006 to December 2009 over a Carrington rotation time basis are presented. A state-of-the-art three-dimensional model for cosmic-ray propagation inside the heliosphere was used to interpret the time-dependent measured fluxes. Proton-to-helium flux ratio time profiles at various rigidities are also presented in order to study any features which could result from the different masses and local interstellar spectra shapes.
- [53] arXiv:2005.08569 [pdf, other]
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Title: Hard - X-rays selected Active Galactic Nuclei. I. A radio view at high-frequenciesAuthors: E. Chiaraluce (1,2), F. Panessa (1), G. Bruni (1), R. D. Baldi (3,4,1), E. Behar (5), F. Vagnetti (2), F. Tombesi (2,6,7,8), I. McHardy (3) ((1) INAF - Istituto di Astrofisica e Planetologia Spaziali, (2) Univerisità di Roma Tor Vergata, (3) University of Southampton, (4) Università degli Studi di Torino, (5) Physics Department, Technion, Haifa, (6) INAF Astronomical Observatory of Rome, (7) Department of Astronomy, University of Maryland, (8) NASA/Goddard Space Flight Center)Comments: Accepted for publication on MNRASSubjects: Astrophysics of Galaxies (astro-ph.GA); High Energy Astrophysical Phenomena (astro-ph.HE)
A thorough study of radio emission in Active Galactic Nuclei (AGN) is of fundamental importance to understand the physical mechanisms responsible for the emission and the interplay between accretion and ejection processes. High frequency radio observations can target the nuclear contribution of smaller emitting regions and are less affected by absorption. We present JVLA 22 and 45 GHz observations of 16 nearby (0.003$\le$z$\le$0.3) hard - X-rays selected AGN at the (sub)-kpc scale with tens uJy beam$^{-1}$ sensitivity. We detected 15/16 sources, with flux densities ranging from hundreds uJy beam$^{-1}$ to tens Jy (specific luminosities from $\sim$10$^{20}$ to $\sim$10$^{25}\,W\,Hz^{-1}$ at 22 GHz). All detected sources host a compact core, with 8 being core-dominated at either frequencies, the others exhibiting also extended structures. Spectral indices range from steep to flat/inverted. We interpret this evidence as either due to a core+jet system (6/15), a core accompanied by surrounding star formation (1/15), to a jet oriented close to the line of sight (3/15), to emission from a corona or the base of a jet (1/15), although there might be degeneracies between different processes. Four sources require more data to shed light on their nature. We conclude that, at these frequencies, extended, optically-thin components are present together with the flat-spectrum core. The ${L_R}/{L_X}\sim10^{-5}$ relation is roughly followed, indicating a possible contribution to radio emission from a hot corona. A weakly significant correlation between radio core (22 and 45 GHz) and X-rays luminosities is discussed in the light of an accretion-ejection framework.
- [54] arXiv:2005.08578 [pdf, other]
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Title: A fully self-consistent model for solar flaresComments: 23 pages, 11 figuresSubjects: Solar and Stellar Astrophysics (astro-ph.SR)
The 'standard solar' flare model collects all physical ingredients identified by multi-wavelength observations of our Sun: magnetic reconnection, fast particle acceleration and the resulting emission at various wavelengths, especially in soft to hard X-ray channels. Its cartoon representation is found throughout textbooks on solar and plasma astrophysics, and guides interpretations of unresolved energetic flaring events on other stars, accretion disks and jets. To date, a fully self-consistent model that reproduces the standard scenario in all its facets is lacking, since this requires the combination of a large scale, multi-dimensional magnetohydrodynamic (MHD) plasma description with a realistic fast electron treatment. Here, we demonstrate such a novel combination, where MHD combines with an analytic fast electron model, adjusted to handle time-evolving, reconnecting magnetic fields and particle trapping. This allows to study (1) the role of fast electron deposition in the triggering of chromospheric evaporation flows; (2) the physical mechanisms that generate various hard X-ray sources at chromospheric footpoints or looptops; and (3) the relationship between soft X-ray and hard X-ray fluxes throughout the entire flare loop evolution. For the first time, this self-consistent solar flare model demonstrates the observationally suggested relationship between flux swept out by the hard X-ray footpoint regions, and the actual reconnection rate at the X-point, which is a major unknown in flaring scenarios. We also demonstrate that a looptop hard X-ray source can result from fast electron trapping.
- [55] arXiv:2005.08580 [pdf, other]
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Title: Lyman-αabsorption beyond the disk of simulated spiral galaxiesAuthors: Bernhard Röttgers (1), Thorsten Naab (1), Miha Cernetic (1), Romeel Davé (2 and 3 and 4), Guinevere Kauffmann (1), Sanchayeeta Borthakur (5), Horst Foidl (6) ((1) Max-Planck Institut für Astrophysik, Garching, Germany, (2) Institute for Astronomy, Royal Observatory, Univ. of Edinburgh, Edinburgh, UK, (3) University of the Western Cape, Bellville, Cape Town, South Africa, (4) South African Astronomical Observatories, Observatory, Cape Town, South Africa, (5) School of Earth and Space Exploration, Arizona State University, Tempe, AZ, USA, (6) Department of Astrophysics, University of Vienna, Wien, Austria)Comments: 18 pages, 20 figuresSubjects: Astrophysics of Galaxies (astro-ph.GA)
We present an analysis of the origin and properties of the circum-galactic medium (CGM) in a suite of 11 cosmological zoom simulations resembling present day spiral galaxies. On average the galaxies retain about 50\% of the cosmic fraction in baryons, almost equally divided into disc (interstellar medium) gas, cool CGM gas and warm-hot CGM gas. At radii smaller than 50 kpc the CGM is dominated by recycled warm-hot gas injected from the central galaxy, while at larger radii it is dominated by cool gas accreted onto the halo. The recycled gas typically accounts for one-third of the CGM mass. We introduce the novel publicly available analysis tool \textsc{pygad} to compute ion abundances and mock absorption spectra. For Lyman-${\alpha}$ absorption we find good agreement of the simulated equivalent width (EW) distribution and observations out to large radii. Disc galaxies with quiescent assembly histories show significantly more absorption along the disc major axis. By comparing the EW and HI column densities we find that CGM Lyman-${\alpha}$ absorbers are best represented by an effective line-width $b\approx 50 - 70$ km s$^{-1}$ that increases mildly with halo mass, larger than typically assumed.
- [56] arXiv:2005.08583 [pdf, ps, other]
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Title: Ridges in the Dark Energy Survey for cosmic trough identificationAuthors: Ben Moews, Morgan A. Schmitz, Andrew J. Lawler, Joe Zuntz, Alex I. Malz, Rafael S. de Souza, Ricardo Vilalta, Alberto Krone-Martins, Emille E. O. Ishida (for the COIN Collaboration)Comments: 12 pages, 5 figures, preprint submitted to MNRASSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Instrumentation and Methods for Astrophysics (astro-ph.IM); Applications (stat.AP); Computation (stat.CO)
Cosmic voids and their corresponding redshift-aggregated projections of mass densities, known as troughs, play an important role in our attempt to model the large-scale structure of the Universe. Understanding these structures leads to tests comparing the standard model with alternative cosmologies, constraints on the dark energy equation of state, and provides evidence to differentiate among gravitational theories. In this paper, we extend the subspace-constrained mean shift algorithm, a recently introduced method to estimate density ridges, and apply it to 2D weak-lensing mass density maps from the Dark Energy Survey Y1 data release to identify curvilinear filamentary structures. We compare the obtained ridges with previous approaches to extract trough structure in the same data, and apply curvelets as an alternative wavelet-based method to constrain densities. We then invoke the Wasserstein distance between noisy and noiseless simulations to validate the denoising capabilities of our method. Our results demonstrate the viability of ridge estimation as a precursor for denoising weak lensing quantities to recover the large-scale structure, paving the way for a more versatile and effective search for troughs.
- [57] arXiv:2005.08621 [pdf, other]
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Title: Constraining dark photon dark matter with fast radio burstsAuthors: Ricardo G. LandimComments: 6 pages, 1 figure, 1 tableSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Phenomenology (hep-ph)
The nature of dark matter is still a mystery that may indicate the necessity for extensions of the Standard Model (SM). The lack of positive signatures for well-known dark matter candidates, such as Weakly Interacting Massive Particles, opens new avenues of exploration. Among them, a new abelian gauge field (dark photon), which kinetically mixes with the SM hypercharge field, is a possible mediator of the interaction between a dark matter candidate and the SM particles. Light dark photons may also comprise partially or entirely the observed dark matter density. Existing limits for the dark photon dark matter parameter space arise from several cosmological and astrophysical sources, and in the present work we constrain its parameter space using cosmic transients, specifically fast radio bursts (FRBs). We use the observed time delay of five detected FRBs (FRB 110220, FRB 121102, FRB 150418, FRB180924 and FRB 190523) and two associations of FRBs with gamma-ray bursts (FRB/GRB 101011A and FRB/GRB 100704A) to obtain conservative upper limits for the dark photon mass. The result $m_{A'}\lesssim 10^{-14}$ eV is virtually independent of the FRBs used and exclude a considerable part of the parameter space, regardless of whether the dark photon constitutes the entirety of dark matter or not.
- [58] arXiv:2005.08653 [pdf, other]
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Title: The Host Galaxies of Rapidly Evolving Transients in the Dark Energy SurveyAuthors: P. Wiseman, M. Pursiainen, M. Childress, E. Swann, M. Smith, L. Galbany, C. Lidman, T. M. Davis, C. P. Gutiérrez, A. Möller, B. P. Thomas, C. Frohmaier, R. J. Foley, S. R. Hinton, L. Kelsey, R. Kessler, G. F. Lewis, M. Sako, D. Scolnic, M. Sullivan, M. Vincenzi, T. M. C. Abbott, M. Aguena, S. Allam, J. Annis, E. Bertin, S. Bhargava, D. Brooks, D. L. Burke, A. Carnero Rosell, D. Carollo, M. Carrasco Kind, J. Carretero, M. Costanzi, L. N. da Costa, H. T. Diehl, P. Doel, S. Everett, P. Fosalba, J. Frieman, J. García-Bellido, E. Gaztanaga, K. Glazebrook, D. Gruen, R. A. Gruendl, J. Gschwend, G. Gutierrez, D. L. Hollowood, K. Honscheid, D. J. James, K. Kuehn, N. Kuropatkin, M. Lima, M. A. G. Maia, J. L. Marshall, P. Martini, F. Menanteau, R. Miquel, A. Palmese, F. Paz-Chinchón, et al. (15 additional authors not shown)Comments: 16 pages, 15 figures, submitted to MNRASSubjects: Astrophysics of Galaxies (astro-ph.GA)
Rapidly evolving transients (RETs), also termed fast blue optical transients (FBOTs), are a distinct class of astrophysical event. They are characterised by lightcurves that decline much faster than common classes supernovae (SNe), span vast ranges in peak luminosity and can be seen to redshifts greater than 1. Their evolution on fast timescales has hindered high quality follow-up observations, and thus their origin and explosion/emission mechanism remains unexplained. In this paper we define the largest sample of RETs to date, comprising 106 objects from the Dark Energy Survey, and perform the most comprehensive analysis of RET host galaxies. Using deep-stacked photometry and emission-lines from OzDES spectroscopy, we derive stellar masses and star-formation rates (SFRs) for 49 host galaxies, and metallicities for 37. We find that RETs explode exclusively in star-forming galaxies and are thus likely associated with massive stars. Comparing RET hosts to samples of host galaxies of other explosive transients as well as field galaxies, we find that RETs prefer galaxies with high specific SFRs, indicating a link to young stellar populations, similar to stripped-envelope SNe. RET hosts appear to show a lack of chemical enrichment, their metallicities akin to long duration gamma-ray bursts and superluminous SN host galaxies. There are no clear relationships between properties of the host galaxies and the peak magnitudes or decline rates of the transients themselves.
- [59] arXiv:2005.08662 [pdf, ps, other]
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Title: The Zwicky Transient Facility Catalog of Periodic Variable StarsComments: 21 pages, 15 figures, resubmitted to ApJS. Comments welcome! The full catalog will be available after the paper is acceptedSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)
The number of known periodic variables has grown rapidly in recent years. Thanks to its large field of view and faint limiting magnitude, the Zwicky Transient Facility (ZTF) offers a unique opportunity to detect variable stars in the northern sky. Here, we exploit ZTF Data Release 2 (DR2) to search for and classify variables down to r ~ 20.6 mag. We classify 781,604 periodic variables into 11 main types using an improved classification method. Comparison with previously published catalogs shows that 621,719 objects (79.5%) are newly discovered or newly classified, including ~700 Cepheids, ~5000 RR Lyrae stars, ~15,000 Delta Scuti variables, ~350,000 eclipsing binaries, ~100,000 long-period variables, and about 150,000 rotational variables. The typical misclassification rate and period accuracy are on the order of 2% and 99%, respectively. 74% of our variables are located at Galactic latitudes, $|b|<10^\circ$. This large sample of Cepheids, RR Lyrae, Delta Scuti stars, and contact (EW-type) eclipsing binaries is helpful to investigate the Galaxy's disk structure and evolution with an improved completeness, areal coverage, and age resolution. Specifically, the northern warp and the disk's edge at distances of 15--20 kpc are significantly better covered than previously. Among rotational variables, RS Canum Venaticorum and BY Draconis-type variables can be separated easily. Our knowledge of stellar chromospheric activity would benefit greatly from a statistical analysis of these types of variables.
- [60] arXiv:2005.08673 [pdf, other]
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Title: The EXOD search for faint transients in XMM-Newton observations: Method and discovery of four extragalactic Type I X-ray BurstersComments: Accepted for publication in A&A. 25 pages, 11 figures, 7 tablesSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); Instrumentation and Methods for Astrophysics (astro-ph.IM)
XMM-Newton has produced an extensive X-ray source catalogue in which the standard pipeline determines the variability of sufficiently bright sources through chi-square and fractional variability tests. Faint sources, however, are not automatically checked for variability, thus overlooking faint, short timescale transients. Our goal is to find new faint, fast transients in XMM-Newton EPIC-pn observations. To that end we have created the EPIC-pn XMM-Newton Outburst Detector (EXOD) algorithm, which we run on the EPIC-pn data available in the 3XMM-DR8 catalogue. In EXOD, we compute the whole-field variability by binning in time the counts in each detector pixel. We next compute the maximum-to-median count difference in each pixel to detect variability. We applied EXOD to 5,751 observations and compared the variability of the detected sources to the standard chi-square and Kolmogorov-Smirnov (KS) variability tests. The algorithm is able to detect periodic and aperiodic variability, short and long flares. Of the sources detected by EXOD, 60-95% are also shown to be variable by the chi-square and KS tests. We obtain a net number of 2,536 variable sources. Of these we investigate the nature of 35 sources with no previously confirmed classification. Amongst the new sources, we find stellar flares and AGNs; but also four extragalactic type I X-ray bursters that double the known neutron-star population in M31. This algorithm is a powerful tool to promptly detect variable sources in XMM-Newton observations. EXOD detects fast transients that other variability tests classify as non-variable due to their short duration and low number of counts. Finally, EXOD allows us to detect and identify the nature of rare compact objects through their variability. We demonstrate this through the discovery of four extragalactic neutron-star low mass X-ray binaries, doubling the number of known neutron stars in M31.
- [61] arXiv:2005.08676 [pdf, ps, other]
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Title: Atmospheric Escape of Close-in Giants around Hot Stars: Far-Ultraviolet Radiation and Photoelectric Heating EffectComments: 9 pages, 6 figures, submitted to ApJSubjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
Atmospheric escape is an important process that controls the long-term evolution of close-in planets. We perform radiation hydrodynamics simulations of photo-evaporation of exoplanets' atmospheres to study the effect of photoelectric heating by far-ultraviolet (FUV) radiation. Specifically, we consider a close-in hot Jupiter around a hot A-star. Hot main-sequence stars emit not only extreme ultraviolet radiation but also FUV radiation, and thus can drive strong atmospheric escape by photoelectric heating. We show that the planetary atmosphere escapes at a rate of $\dot{M}\sim10^{14}\,\mathrm{g/s}$ if the atmosphere contains heavy elements and dust grains with the level of ten percent of the solar metallicity. Close-in planets around hot stars can lose a significant fraction of the atmosphere during the long-term evolution. We also explore the metallicity dependence of the FUV driven escape. The mass-loss rate increases with increasing the atmosphere's metallicity because of the enhanced photoelectric heating, but the stellar FUV flux decreases with increasing stellar metallicity. The net dependence nearly cancels if we assume the same or similar metallicities for the planet and the host star. We derive an accurate estimate for the mass-loss rate as a function of FUV flux and metallicity, and of the planet's characteristics. The FUV driven atmospheric escape may be a key process to understand and explain the so-called sub-Jovian desert.
- [62] arXiv:2005.08688 [pdf, ps, other]
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Title: The rotation-activity relation of M dwarfs: From K2 to TESS and PLATOComments: Accepted for publication in Astronomical Notes (AN). 28 pages 11 figures, 4 tables. The tables are available in ascii format at this http URLSubjects: Solar and Stellar Astrophysics (astro-ph.SR)
Studies of the rotation-activity relation of late-type stars are essential to enhance our understanding of stellar dynamos and angular momentum evolution. We study the rotation-activity relation with K2 for M dwarfs where it is especially poorly understood. We analyzed the light curves of all bright and nearby M dwarfs form the Superblink proper motion catalog that were in the K2 field of view. For a sample of 430 M dwarfs observed in campaigns C0-C19 in long cadence mode we determined the rotation period and a wealth of activity diagnostics. Our study of the rotation-activity relation based on photometric activity indicators confirmed the previously published abrupt change of the activity level at a rotation period of ~10d. Our more than three times larger sample increases the statistical significance of this finding.
- [63] arXiv:2005.08716 [pdf]
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Title: The dynamo action for red dwarfs and red giant and supergiant starsAuthors: D. V. SarafopoulosComments: 40 pages, 3 figuresSubjects: Solar and Stellar Astrophysics (astro-ph.SR)
We investigate the possibility to apply the already suggested by Sarafopoulos (2017, 2019) main concept of dynamo action to red dwarfs and red giant and supergiant stars. Thus, we attempt to establish a unified dynamo action, being potentially at work at widely varying stellar domains. Thus, the powerful, unique and leading entity generating the primary stellar magnetic field remains the so-called Torus structure. Within the Torus the same sign charges are mutually attracted and the Torus could be simulated as a superconductor. An existing gradient of the rotation rate accumulates net charge in the Torus, and the resulting toroidal current becomes the driving source of the magnetic field. In turn, there is a complicated network of secondary interactions that affect and modulate the whole star's magnetic behaviour. Our dynamo action is potentially at work in fully and partly convecting stars. A major finding is that the strength of the magnetic field, for stars of the same spectral type, is essentially controlled by the size of the star; we suggest that, the larger the star, the deeper inward the Torus is formed. The formation of a single Torus is essentially associated with a large-scale strong, poloidal and axisymmetric magnetic field topology, whereas the generation of a weaker multipolar, non-axisymmetric field configuration in rapid evolution can result from a double-Torus structure (like the solar case). The same basic concept is scaled up or down. Moreover, we identify four key parameters associated with the magnetic field of red dwarfs, giants and supergiants: First, the rotation speed; second, the steepness of the radial gradient of the rotation rate in the shear layer; third, the distance of the Torus from the photosphere and fourth, the cross-sectional area of the Torus. The third and fourth key parameters are introduced for the first time.
- [64] arXiv:2005.08718 [pdf, other]
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Title: Nature of Compton-thick Active Galactic Nuclei in "Non-merging'' Luminous Infrared Galaxies UGC 2608 and NGC 5135 Revealed with Broadband X-ray SpectroscopyAuthors: Satoshi Yamada, Yoshihiro Ueda, Atsushi Tanimoto, Saeko Oda, Masatoshi Imanishi, Yoshiki Toba, Claudio RicciComments: 15 pages, 12 figures, and 3 tables, accepted for publication in ApJSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); Astrophysics of Galaxies (astro-ph.GA)
We have analyzed the broadband X-ray spectra of active galactic nuclei (AGNs) in two "non-merging" luminous infrared galaxies (LIRGs) UGC 2608 and NGC 5135, utilizing the data of NuSTAR, Suzaku, XMM-Newton, and Chandra. Applying the X-ray clumpy-torus model (XCLUMPY: Tanimoto et al. 2019), we find that both sources have similar spectra characterized by Compton-thick (CT) absorption ($N_{\rm H} \sim$ 5-7 $\times$ $10^{24}$ cm$^{-2}$) and small torus angular width ($\sigma$ $<$ 20$^{\circ}$). The intrinsic 2-10 keV luminosities are $3.9^{+2.2}_{-1.7}$ $\times$ $10^{43}$ erg s$^{-1}$ (UGC 2608) and $2.0^{+3.3}_{-1.0}$ $\times$ $10^{43}$ erg s$^{-1}$ (NGC 5135). The [O IV]-to-nuclear-12 $\mu$m luminosity ratios are larger than those of typical Seyferts, which are consistent with the torus covering factors ($C_{\rm T} \lesssim$ 0.7) estimated from the torus angular widths and column densities by X-ray spectroscopy. The torus covering factors and Eddington ratios ($\lambda_{\rm Edd} \sim$ 0.1) follow the relation found by Ricci et al. (2017c) for local AGNs, implying that their tori become geometrically thin due to significant radiation pressure of the AGN that blows out some part of the tori. These results indicate that the CT AGNs in these "non-merger" LIRGs are just a normal AGN population seen edge-on through a large line-of-sight column density. They are in contrast to the buried CT AGNs in late-stage mergers that have large torus covering factors even at large Eddington ratios.
- [65] arXiv:2005.08727 [pdf, other]
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Title: Inspiraling double compact object detection and lensing rate -- forecast for DECIGO and B-DECIGOAuthors: Aleksandra Piórkowska-Kurpas, Shaoqi Hou, Marek Biesiada, Xuheng Ding, Shuo Cao, Xilong Fan, Seiji Kawamura, Zong-Hong ZhuComments: 12 pages, 7 figures, submitted to the Astrophysical JournalSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
Emergence of gravitational wave (GW) astronomy revived the interest in exploring the low frequency GW spectrum inaccessible from the ground. Satellite GW observatory DECIGO in its original configuration and the currently proposed smaller scale B-DECIGO are aimed to cover deci-Hertz part of the GW spectrum, which fills the gap between LISA mili-Hertz and deca- to kilo-Hertz range probed by ground-based detectors. In this paper we forecast the detection rates of inspiraling double compact objects (DCOs) and the unresolved confusion noise from these sources in DECIGO and B-DECIGO. In the context of DECIGO we use, for the first time, the population synthesis intrinsic inspiral rates of NS-NS, BH-NS and BH-BH systems. We also estimate the expected gravitational lensing rates of such sources for DECIGO and B-DECIGO. The result is that yearly detection of DCOs inspirals for the DECIGO is of order of $10^4 - 10^5$, while for a much smaller scale B-DECIGO they are about $10^2 - 10^4$ depending on the DCO population considered. Taking into account that considerable part of these events would be detectable by ground-based GW observatories the added value of DECIGO/B-DECIGO could be substantial. DECIGO will also be able to register $5-50$ lensed NS-NS inspirals and up to O(100) BH-BH inspirals. On the contrary, predictions for the B-DECIGO are pessimistic: only the optimistic common envelope scenario of DCO formation could yield a few lensed BH-BH inspirals per year. We also address the question of the magnification bias in the GW event catalogs of DECIGO and B-DECIGO.
- [66] arXiv:2005.08751 [pdf, other]
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Title: Vector speckle grid: instantaneous incoherent speckle grid for high-precision astrometry and photometry in high-contrast imagingAuthors: Steven P. BosComments: Accepted for publication in A&ASubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Earth and Planetary Astrophysics (astro-ph.EP)
Photometric and astrometric monitoring of directly imaged exoplanets will deliver unique insights into their rotational periods, the distribution of cloud structures, weather, and orbital parameters. As the host star is occulted by the coronagraph, a speckle grid (SG) is introduced to serve as astrometric and photometric reference. Speckle grids are implemented as diffractive pupil-plane optics that generate artificial speckles at known location and brightness. Their performance is limited by the underlying speckle halo caused by evolving uncorrected wavefront errors. The speckle halo will interfere with the coherent SGs, affecting their photometric and astrometric precision. Our aim is to show that by imposing opposite amplitude or phase modulation on the opposite polarization states, a SG can be instantaneously incoherent with the underlying halo, greatly increasing the precision. We refer to these as vector speckle grids (VSGs). We derive analytically the mechanism by which the incoherency arises and explore the performance gain in idealised simulations under various atmospheric conditions. We show that the VSG is completely incoherent for unpolarized light and that the fundamental limiting factor is the cross-talk between the speckles in the grid. In simulation, we find that for short-exposure images the VSG reaches a $\sim$0.3-0.8\% photometric error and $\sim$$3-10\cdot10^{-3}$ $\lambda/D$ astrometric error, which is a performance increase of a factor $\sim$20 and $\sim$5, respectively. Furthermore, we outline how VSGs could be implemented using liquid-crystal technology to impose the geometric phase on the circular polarization states. The VSG is a promising new method for generating a photometric and astrometric reference SG that has a greatly increased astrometric and photometric precision.
- [67] arXiv:2005.08782 [pdf, other]
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Title: Cross-correlating 2MRS galaxies with UHECR flux from Pierre Auger ObservatoryAuthors: Pavel MotlochComments: 7 pages, 5 figures, comments welcomeSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA)
We apply a recently proposed cross-correlation power spectrum technique to study relationship between the ultra-high energy cosmic ray flux from the Pierre Auger Observatory and galaxies from the 2MASS Redshift Survey. Using a simple linear bias model relative to the galaxy auto power spectrum we are able to constrain the value of bias to be less than 5%, with the best fit value of about 1% detected with statistical significance of $\sim 1.8\sigma$. We study energy dependence of the bias, but the small sample size does not allow us to reach any statistically significant conclusions. For the cosmic ray events above 52 EeV we discover a curious excess cross-correlation at $\sim 1^\circ$ degree scales. Given similar cross-correlation is not visible at larger angular scales, statistical fluctuation seems like the most plausible explanation.
- [68] arXiv:2005.08810 [pdf, other]
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Title: APEX CO observations towards the photodissociation region of RCW120Authors: Miguel Figueira, Annie Zavagno, Leonardo Bronfman, Delphine Russeil, Ricardo Finger, Frédéric SchullerComments: 13 pages, 12 Figures To be published in A&ASubjects: Astrophysics of Galaxies (astro-ph.GA)
The edges of ionized (HII) regions are important sites for the formation of (high-mass) stars. Indeed, at least 30% of the galactic high mass star formation is observed there. The radiative and compressive impact of the HII region could induce the star formation at the border following different mechanisms such as the Collect & Collapse (C&C) or the Radiation Driven Implosion (RDI) models and change their properties. We study the properties of two zones located in the Photo Dissociation Region (PDR) of the Galactic HII region RCW120 and discussed them as a function of the physical conditions and young star contents found in both clumps. Using the APEX telescope, we mapped two regions of size 1.5'$\times$1.5' toward the most massive clump of RCW120 hosting young massive sources and toward a clump showing a protrusion inside the HII region and hosting more evolved low-mass sources. The $^{12}$CO($J=3-2$), $^{13}$CO($J=3-2$) and C$^{18}$O($J=3-2$) lines are used to derive the properties and dynamics of these clumps. We discuss their relation with the hosted star-formation. The increase of velocity dispersion and $T_{ex}$ are found toward the center of the maps, where star-formation is observed with Herschel. Furthermore, both regions show supersonic Mach number. No strong evidences have been found concerning the impact of far ultraviolet (FUV) radiation on C$^{18}$O photodissociation. The fragmentation time needed for the C&C to be at work is equivalent to the dynamical age of RCW120 and the properties of region B are in agreement with bright-rimmed clouds. It strengthens the fact that, together with evidences of compression, C&C might be at work at the edges of RCW120. Additionally, the clump located at the eastern part of the PDR is a good candidate of pre-existing clump where star-formation may be induced by the RDI mechanism.
- [69] arXiv:2005.08813 [pdf, other]
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Title: Observational Constraints on Axion(s) with a Cosmological ConstantComments: 18 pages, LateX style. Comments welcomeSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th)
The present work deals with a dark energy model that has an oscillating scalar field potential along with a cosmological constant (CC). The oscillating part of the potential represents the contribution of a light axion field in the dark energy that has its origin in the String-Axiverse scenario. The model has been confronted with the latest cosmological observations. The results show that a sub-Planckian value of the axion field decay constant is consistent at 1$\sigma$ confidence level. The oscillating feature in the scalar field evolution and in the equation of state for the dark energy can be observed at 2$\sigma$ confidence interval. It is also observed that cluster number counts in this axion model are suppressed compared to the $\Lambda$CDM and this suppression is enhanced for the sub-Planckian values for the axion decay constant.
- [70] arXiv:2005.08830 [pdf, other]
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Title: Of Harbingers and Higher Modes: Improved gravitational-wave early-warning of compact binary mergersAuthors: Shasvath J. Kapadia, Mukesh Kumar Singh, Md Arif Shaikh, Deep Chatterjee, Parameswaran AjithComments: 6 pages, 4 figuresSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc)
A crucial component to maximizing the science gain from the multi-messenger follow-up of gravitational-wave (GW) signals from compact binary mergers is the prompt discovery of the electromagnetic counterpart. Ideally, the GW detection and localization must be reported early enough to allow for telescopes to slew to the location of the GW-event before the onset of the counterpart. However, the time available for early warning is limited by the short duration spent by the dominant ($\ell = m = 2$) mode within the detector's frequency band, before the binary merges. This can be circumvented if one could exploit the fact that GWs also contain contributions from higher modes that oscillate at higher harmonics of the orbital frequency, which enter the detector band well before the dominant mode. In this letter, we show that these higher modes, although smaller in amplitude, will enable us to significantly improve the early warning time for compact binaries with asymmetric masses (such as neutron-star-black-hole binaries). We investigate the gain in the early-warning time when the $\ell = m = 3$ and $\ell = m = 4$ modes are included in addition to the dominant mode. This is done by using a fiducial threshold of 1000 sq. deg. on the localization sky-area for electromagnetic follow-ups. We find that, in LIGO's projected "O5-like" network of five GW detectors, for neutron-star-black-hole mergers expected to produce counterparts, we get early-warning gains of up to $\sim 25$ s, assuming the source at a distance of $40$ Mpc. These gains increase to $\sim 40$ s in the same five-detector network with three LIGO detectors upgraded to "Voyager" sensitivity, and $\sim 5$ min. in a third-generation network when the source is placed at $100$ Mpc.
- [71] arXiv:2005.08850 [pdf, other]
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Title: VLT/SPHERE survey for exoplanets around young, early-type stars including systems with multi-belt architecturesAuthors: M. Lombart, G. Chauvin, P. Rojo, E. Lagadec, P. Delorme, H. Beust, M. Bonnefoy, R. Galicher, R. Gratton, D. Mesa, M. Bonavita, F. Allard, A. Bayo, A. Boccaletti, S. Desidera, J. Girard, J. Jenkins, H. Klahr, G. Laibe, A.-M. Lagrange, C. Lazzoni, G.-D. Marleau, D. Minniti, C. MordasiniComments: Accepted for publication in Astronomy & Astrophysics. 12 pages, 9 figuresSubjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
Dusty debris disks around pre- and main-sequence stars are potential signposts for the existence of planetesimals and exoplanets. Giant planet formation is therefore expected to play a key role in the evolution of the disk. This is indirectly confirmed by extant sub-millimeter near-infrared images of young protoplanetary and cool dusty debris disks around main sequence stars usually showing substantial spatial structures. A majority of recent discoveries of imaged giant planets have been obtained around young, early-type stars hosting a circumstellar disk. In this context, we have carried out a direct imaging program designed to maximize our chances of giant planet discovery and targeting twenty-two young, early-type stars. About half of them show indication of multi-belt architectures. Using the IRDIS dual-band imager and the IFS integral field spectrograph of SPHERE to acquire high-constrast coronagraphic differential near-infrared images, we have conducted a systematic search in the close environment of these young, dusty and early-type stars. We confirmed that companions detected around HIP 34276, HIP 101800 and HIP 117452 are stationary background sources and binary companions. The companion candidates around HIP 8832, HIP 16095 and HIP 95619 are determined as background contamination. For stars for which we infer the presence of debris belts, a theoretical minimum mass for planets required to clear the debris gaps can be calculated . The dynamical mass limit is at least $0.1 M_J$ and can exceed $1 M_J$. Direct imaging data is typically sensitive to planets down to $\sim 3.6 M_J$ at 1 $''$, and $1.7 M_J$ in the best case. These two limits tightly constrain the possible planetary systems present around each target. These systems will be probably detectable with the next generation of planet imagers.
- [72] arXiv:2005.08853 [pdf, other]
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Title: Optimal target assignment for massive spectroscopic surveysSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Robotics (cs.RO)
Robotics have recently contributed to cosmological spectroscopy to automatically obtain the map of the observable universe using robotic fiber positioners. For this purpose, an assignment algorithm is required to assign each robotic fiber positioner to a target associated with a particular observation. The assignment process directly impacts on the coordination of robotic fiber positioners to reach their assigned targets. In this paper, we establish an optimal target assignment scheme which simultaneously provides the fastest coordination accompanied with the minimum of colliding scenarios between robotic fiber positioners. In particular, we propose a cost function by whose minimization both of the cited requirements are taken into account in the course of a target assignment process. The applied simulations manifest the improvement of convergence rates using our optimal approach. We show that our algorithm scales the solution in quadratic time in the case of full observations. Additionally, the convergence time and the percentage of the colliding scenarios are also decreased in both supervisory and hybrid coordination strategies.
- [73] arXiv:2005.08880 [pdf, other]
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Title: Super-Rayleigh Slopes in Transmission Spectra of Exoplanets Generated by Photochemical HazeComments: 9 pages, 5 figures, accepted for publication in ApJLSubjects: Earth and Planetary Astrophysics (astro-ph.EP)
Spectral slopes in optical transmission spectra of exoplanetary atmospheres encapsulate information on the properties of exotic clouds. The slope is usually attributed to the Rayleigh scattering caused by tiny aerosol particles, whereas recent retrieval studies have suggested that the slopes are often steeper than the canonical Rayleigh slopes. Here, we propose that photochemical haze formed in vigorously mixing atmospheres can explain such super-Rayleigh slopes. We first analytically show that the spectral slope can be steepened by the vertical opacity gradient in which atmospheric opacity increases with altitude. Using a microphysical model, we demonstrate that such opacity gradient can be naturally generated by photochemical haze, especially when the eddy mixing is substantially efficient. The transmission spectra of hazy atmospheres can be demarcated into four typical regimes in terms of the haze mass flux and eddy diffusion coefficient. We find that the transmission spectrum can have the spectral slope 2--4 times steeper than the Rayleigh slope if the eddy diffusion coefficient is sufficiently high and the haze mass flux falls into a moderate value. Based on the eddy diffusion coefficient suggested by a recent study of atmospheric circulations, we suggest that photochemical haze preferentially generates super-Rayleigh slopes at planets with equilibrium temperature of 1000--1500 K, which might be consistent with results of recent retrieval studies. Our results would help to interpret the observations of spectral slopes from the perspective of haze formation.
- [74] arXiv:2005.08881 [pdf, other]
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Title: The large Trans-Neptunian Object 2002 TC$_{302}$ from combined stellar occultation, photometry and astrometry dataAuthors: J. L. Ortiz, P. Santos-Sanz, B. Sicardy, G. Benedetti-Rossi, R. Duffard, N. Morales, F. Braga-Ribas, E. Fernández-Valenzuela, V. Nascimbeni, D. Nardiello, A. Carbognani, L. Buzzi, A. Aletti, P. Bacci, M. Maestripieri, L. Mazzei, H. Mikuz, J. Skvarc, F. Ciabattari, F. Lavalade, G. Scarfi, J. M. Mari, M. Conjat, S. Sposetti, M. Bachini, G. Succi, F. Mancini, M. Alighieri, E. Dal Canto, M. Masucci, M. Vara-Lubiano, P. J. Gutiérrez, J. Desmars, J. Lecacheux, R. Vieira-Martins, J. I. B. Camargo, M. Assafin, F. Colas, W. Beisker, R. Behrend, T. G. Mueller, E. Meza, A. R. Gomes-Junior, F. Roques, F. Vachier, S. Mottola, S. Hellmich, A. Campo Bagatin, A. Alvarez-Candal, S. Cikota, A. Cikota, J. M. Christille, A. Pál, C. Kiss, T. Pribulla, R. Komžík, J. M. Madiedo, V. Charmandaris, et al. (23 additional authors not shown)Comments: Accepted for publication in Astronomy & Astrophysics. 14 pages, 9 figuresSubjects: Earth and Planetary Astrophysics (astro-ph.EP)
On 28th January 2018, the large Trans-Neptunian Object (TNO) 2002TC302 occulted a m$_v= $15.3 star with ID 130957813463146112 in the Gaia DR2 stellar catalog. 12 positive occultation chords were obtained from Italy, France, Slovenia and Switzerland. Also, 4 negative detections were obtained near the north and south limbs. This represents the best observed stellar occultation by a TNO other than Pluto, in terms of the number of chords published thus far. From the 12 chords, an accurate elliptical fit to the instantaneous projection of the body, compatible with the near misses, can be obtained. The resulting ellipse has major and minor axes of 543 $\pm$ 18 km and 460 $\pm$ 11 km, respectively, with a position angle of 3 $\pm$ 1 degrees for the minor axis. This information, combined with rotational light curves obtained with the 1.5m telescope at Sierra Nevada Observatory and the 1.23m telescope at Calar Alto observatory, allows us to derive possible 3D shapes and density estimations for the body, based on hydrostatic equilibrium assumptions. The effective area equivalent diameter is $\sim$ 84 km smaller than the radiometrically derived diameter using thermal data from Herschel and Spitzer Space Telescopes. This might indicate the existence of an unresolved satellite of up to $\sim$ 300 km in diameter, to account for all the thermal flux, although the occultation and thermal diameters are compatible within their error bars given the considerable uncertainty of the thermal results. The existence of a potential satellite also appears to be consistent with other ground-based data presented here. From the effective occultation diameter combined with H$_V$ measurements we derive a geometric albedo of 0.147 $\pm$ 0.005, which would be somewhat smaller if 2002TC302 has a satellite. The best occultation light curves do not show any signs of ring features or any signatures of a global atmosphere.
- [75] arXiv:2005.08905 [pdf, other]
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Title: Investigating the physical conditions in extended system hosting mid-infrared bubble N14Comments: 25 pages, 13 figures, 5 Tables, Accepted for publication in The Astrophysical JournalSubjects: Astrophysics of Galaxies (astro-ph.GA)
To observationally explore physical processes, we present a multi-wavelength study of a wide-scale environment toward l = 13.7 - 14.9 degrees containing a mid-infrared bubble N14. The analysis of 12CO, 13CO, and C18O gas at [31.6, 46] km/s reveals an extended physical system (extension ~59 pc x 29 pc), which hosts at least five groups of the ATLASGAL 870 micron dust clumps at d ~3.1 kpc. These spatially-distinct groups/sub-regions contain unstable molecular clumps, and are associated with several Class I young stellar objects (mean age ~0.44 Myr). At least three groups of ATLASGAL clumps associated with the expanding HII regions (including the bubble N14) and embedded infrared dark clouds, devoid of the ionized gas, are found in the system. The observed spectral indices derived using the GMRT and THOR radio continuum data suggest the presence of non-thermal emission with the HII regions. High resolution GMRT radio continuum map at 1280 MHz traces several ionized clumps powered by massive B-type stars toward N14, which are considerably young (age ~10^3 - 10^4 years). Locally, early stage of star formation is evident toward all the groups of clumps. The position-velocity maps of 12CO, 13CO, and C18O exhibit an oscillatory-like velocity pattern toward the selected longitude range. Considering the presence of different groups/sub-regions in the system, the oscillatory pattern in velocity is indicative of the fragmentation process. All these observed findings favour the applicability of the global collapse scenario in the extended physical system, which also seems to explain the observed hierarchy.
- [76] arXiv:2005.08927 [pdf, other]
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Title: Dark Matter, Dark Energy and Fundamental AccelerationComments: 8 pages; This essay received an honorable mention in the Gravity Research Foundation 2020 Awards for Essays on Gravitation competitionSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
We discuss the existence of an acceleration scale in galaxies and galaxy clusters. The presence of the same acceleration scale found at very different scales and in very different astrophysical objects strongly supports the existence of a fundamental acceleration scale governing the observed gravitational physics. We also comment on the implication of such a fundamental acceleration scale on the problem of dark matter. We discuss the relevance of the fundamental acceleration for the nature of dark matter as well as for structure formation to be explored in future numerical simulations.
- [77] arXiv:2005.08937 [pdf, ps, other]
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Title: High-Energy Neutrino and Gamma-Ray Emission from Tidal Disruption Events and Implications for AT2019dsgComments: 14 pages, 5 figuresSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Phenomenology (hep-ph)
Tidal disruption events (TDE) have been considered as cosmic-ray and neutrino sources for a decade. We suggest two classes of new scenarios for high-energy multi-messenger emission from TDEs that do not have to harbor powerful jets. First, we investigate high-energy neutrino and gamma-ray production in the core region of a supermassive black hole. In particular, we show that $\sim10-100$~TeV neutrinos and MeV gamma-rays can efficiently be produced in hot coronae around an accretion disk. We also study the consequences of possible particle acceleration in radiatively inefficient accretion flows (RIAFs). Second, we consider possible cosmic-ray acceleration by disk-driven winds or interactions between tidal streams, and show that subsequent hadronuclear and photohadronic interactions inside the TDE debris lead to GeV-TeV neutrinos and sub-GeV cascade gamma-rays. We demonstrate that these models should be accompanied by hard X-rays and soft gamma-rays, which can be used for future observational tests. By considering the corona, RIAF, hidden wind, and hidden jet models, we discuss the implications of the observation of the high-energy neutrino IceCube-191001A in coincidence with the TDE AT2019dsg. It is not yet possible to be conclusive about their physical association, but we find that the most optimistic cases of the corona and hidden disk-wind models can be consistent with the observation of IceCube-191001A with a few percent chance probability, whereas jet models are unlikely to explain the multi-messenger observations.
Cross-lists for Tue, 19 May 20
- [78] arXiv:2005.07779 (cross-list from cs.CV) [pdf, other]
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Title: Transformation Based Deep Anomaly Detection in Astronomical ImagesComments: 8 pages, 6 figures, 4 tables. Accepted for publication in proceedings of the IEEE World Congress on Computational Intelligence (IEEE WCCI), Glasgow, UK, 19-24 July, 2020Subjects: Computer Vision and Pattern Recognition (cs.CV); Instrumentation and Methods for Astrophysics (astro-ph.IM)
In this work, we propose several enhancements to a geometric transformation based model for anomaly detection in images (GeoTranform). The model assumes that the anomaly class is unknown and that only inlier samples are available for training. We introduce new filter based transformations useful for detecting anomalies in astronomical images, that highlight artifact properties to make them more easily distinguishable from real objects. In addition, we propose a transformation selection strategy that allows us to find indistinguishable pairs of transformations. This results in an improvement of the area under the Receiver Operating Characteristic curve (AUROC) and accuracy performance, as well as in a dimensionality reduction. The models were tested on astronomical images from the High Cadence Transient Survey (HiTS) and Zwicky Transient Facility (ZTF) datasets. The best models obtained an average AUROC of 99.20% for HiTS and 91.39% for ZTF. The improvement over the original GeoTransform algorithm and baseline methods such as One-Class Support Vector Machine, and deep learning based methods is significant both statistically and in practice.
- [79] arXiv:2005.08010 (cross-list from gr-qc) [pdf, ps, other]
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Title: Gravitational Landau Damping for massive scalar modesSubjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA); High Energy Astrophysical Phenomena (astro-ph.HE); Plasma Physics (physics.plasm-ph)
We establish the existence of gravitational Landau damping for massive scalar modes in a non-collisional gas of particles, whose distribution function, assumed homogeneous and isotropic, is governed by a Vlasov equation. Then, by describing the medium with the J\"uttner-Maxwell distribution, we find that damping occurs when the wave phase velocity in the medium is subluminal, which constraints the mass of the scalar mode to be smaller than the proper frequency of the medium. The damping rate, however, calculated in the limit of wave phase velocity much larger than the particle thermal velocity, appears to be negligible on the temporal and spatial scales achievable by present instruments.
- [80] arXiv:2005.08227 (cross-list from physics.space-ph) [pdf, ps, other]
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Title: Stochastic ion and electron heating on drift instabilities at the bow shockAuthors: Krzysztof StasiewiczComments: MNRAS, accepted, 6 pages, 5 figuresSubjects: Space Physics (physics.space-ph); Solar and Stellar Astrophysics (astro-ph.SR); Plasma Physics (physics.plasm-ph)
The analysis of the wave content inside a perpendicular bow shock indicates that heating of ions is related to the Lower-Hybrid-Drift (LHD) instability, and heating of electrons to the Electron-Cyclotron-Drift (ECD) instability. Both processes represent stochastic acceleration caused by the electric field gradients on the electron gyroradius scales, produced by the two instabilities. Stochastic heating is a single particle mechanism where large gradients break adiabatic invariants and expose particles to direct acceleration by the DC- and wave-fields. The acceleration is controlled by function $\chi = m_iq_i^{-1} B^{-2}$div($\mathbf{E}$), which represents a general diagnostic tool for processes of energy transfer between electromagnetic fields and particles, and the measure of the local charge non-neutrality. The identification was made with multipoint measurements obtained from the Magnetospheric Multiscale spacecraft (MMS). The source for the LHD instability is the diamagnetic drift of ions, and for the ECD instability the source is ExB drift of electrons. The conclusions are supported by laboratory diagnostics of the ECD instability in Hall ion thrusters.
- [81] arXiv:2005.08258 (cross-list from gr-qc) [pdf, ps, other]
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Title: The generalized second law of thermodynamics with Barrow entropyComments: 4 pagesSubjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Theory (hep-th)
We investigate the validity of the generalized second law of thermodynamics, applying Barrow entropy for the horizon entropy. The former arises from the fact that the black-hole surface may be deformed due to quantum-gravitational effects, quantified by a new exponent $\Delta$. We calculate the entropy time-variation in a universe filled with the matter and dark energy fluids, as well as the corresponding quantity for the apparent horizon. We show that although in the case $\Delta=0$, which corresponds to usual entropy, the sum of the entropy enclosed by the apparent horizon plus the entropy of the horizon itself is always a non-decreasing function of time and thus the generalized second law of thermodynamics is valid, in the case where quantum-gravitational corrections switch on this is not true anymore, and the generalized second law of thermodynamics may be violated, depending on the universe evolution.
- [82] arXiv:2005.08313 (cross-list from gr-qc) [pdf, ps, other]
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Title: f(G) Noether cosmologySubjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Theory (hep-th)
We develop the $n$-dimensional cosmology for $f(\mathcal{G})$ gravity, where $\mathcal{G}$ is the \emph{Gauss-Bonnet} topological invariant. Specifically, by the so-called Noether Symmetry Approach, we select $f(\mathcal{G})\simeq \mathcal{G}^k$ power-law models where $k$ is a real number. In particular, the case $k = 1/2$ for $n=4$ results equivalent to General Relativity showing that we do not need to impose the action $R+f(\mathcal{G})$ to reproduce the Einstein theory. As a further result, de Sitter solutions are recovered in the case where $f(\mathcal{G})$ is non-minimally coupled to a scalar field. This means that issues like inflation and dark energy can be addressed in this framework. Finally, we develop the Hamiltonian formalism for the related minisuperspace and discuss the quantum cosmology for this model.
- [83] arXiv:2005.08320 (cross-list from nucl-th) [pdf, ps, other]
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Title: Investigation of the thermal effects on the nuclear matterComments: 10 pages, 9 figures. comments are welcomeSubjects: Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE)
We study the thermal effects on the nuclear matter properties such as binding energy, incompressibility, free symmetry energy and its coefficients using NL3 and G3 parameter sets of relativistic mean-field models. These models being consistent with the properties of cold nuclear matter have also been used to study the effect of temperature by incorporating the Fermi function. The critical temperature for the liquid-gas phase transition in the symmetric nuclear matter is found to be 14.60 and 15.37 MeV for NL3 and G3 parameter sets respectively, which is in excellent agreement with previous theoretical and experimental studies. We inspect that the properties related to the second differential coefficient of the binding energy and free symmetry energy at saturation density ( i.e. K0{n,T} and Qsym,0 ) exhibit the contrary effects for NL3 and G3 parameters as the temperature increases. We find that the prediction of saturated curvature parameter ( Ksym,0 ) for G3 equation of state at finite temperature favour the combined analysis of Ksym,0 for the existence of massive pulsars, gravitational waves from GW170817 and NICER observations of PSR J0030+0451. Further, we investigate the cooling mechanism of newly born stars through neutrino emissivity controlled by direct Urca process and instate some interesting remarks about neutrino emissivity. We also deliberate the effect of temperature on the M-R profile of Proto-Neutron star.
- [84] arXiv:2005.08324 (cross-list from hep-th) [pdf, other]
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Title: String Cosmology backgrounds from Classical String GeometryComments: 27 pages, 1 figureSubjects: High Energy Physics - Theory (hep-th); Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph)
We introduce a very early universe model based on the thermodynamics of a gas of closed strings in a background which is non-perturbative in $\alpha'$. Upon considering the fully $\alpha'$-corrected equations extended to include certain anisotropic cosmological backgrounds, we describe the evolution of the system in three different stages parametrized by the gas' equation of state. Using standard string thermodynamical arguments, we start with an isotropic 10-dimensional universe inside the string scale and evolve it towards a universe with four large spacetime dimensions and six stabilized internal dimensions in the Einstein frame.
- [85] arXiv:2005.08428 (cross-list from gr-qc) [pdf, ps, other]
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Title: Cosmology and gravitational waves in consistent $D\to 4$ Einstein-Gauss-Bonnet gravityComments: 14 pages, no figuresSubjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Theory (hep-th)
In a very recent paper [1], we have proposed a novel $4$-dimensional gravitational theory with two dynamical degrees of freedom, which serves as a consistent realization of $D\to4$ Einstein-Gauss-Bonnet gravity with the rescaled Gauss-Bonnet coupling constant $\tilde{\alpha}$. In the present paper, we study cosmological implications of the theory in the presence of a perfect fluid and clarify the similarities and differences between the results obtained from the consistent $4$-dimensional theory and those from the previously considered, naive (and inconsistent) $D\rightarrow 4$ limit. Studying the linear perturbations, we explicitly show that the theory only has tensorial gravitational degrees of freedom (besides the matter degree) and that for $\tilde{\alpha}>0$ and $\dot{H}<0$, perturbations are free of any pathologies so that we can implement the setup to construct early and/or late time cosmological models. Interestingly, a $k^4$ term appears in the dispersion relation of tensor modes which plays significant roles at small scales and makes the theory different than not only general relativity but also many other modified gravity theories as well as the naive (and inconsistent) $D\to 4$ limit. Taking into account the $k^4$ term, the observational constraint on the propagation of gravitational waves yields the bound $\tilde{\alpha} \lesssim {\cal O}(1)\,{\rm eV}^{-2}$. This is the first bound on the only parameter (besides the Newton's constant and the choice of a constraint that stems from a temporal gauge fixing) in the consistent theory of $D\to 4$ Einstein-Gauss-Bonnet gravity.
- [86] arXiv:2005.08507 (cross-list from gr-qc) [pdf, ps, other]
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Title: The exterior gravitational potential of toroidsComments: 15 pages, 12 figures, accepted for publication in MNRASSubjects: General Relativity and Quantum Cosmology (gr-qc); Instrumentation and Methods for Astrophysics (astro-ph.IM); Plasma Physics (physics.plasm-ph)
We perform a bivariate Taylor expansion of the axisymmetric Green function in order to determine the exterior potential of a static thin toroidal shell having a circular section, as given by the Laplace equation. This expansion, performed at the centre of the section, consists in an infinite series in the powers of the minor-to-major radius ratio $e$ of the shell. It is appropriate for a solid, homogeneous torus, as well as for inhomogeneous bodies (the case of a core stratification is considered). We show that the leading term is identical to the potential of a loop having the same main radius and the same mass | this "similarity" is shown to hold in the ${\cal O}(e^2)$ order. The series converges very well, especially close to the surface of the toroid where the average relative precision is $\sim 10^{-3}$ for $e\! = \!0.1$ at order zero, and as low as a few $10^{-6}$ at second order. The Laplace equation is satisfied {\em exactly} in every order, so no extra density is induced by truncation. The gravitational acceleration, important in dynamical studies, is reproduced with the same accuracy. The technique also applies to the magnetic potential and field generated by azimuthal currents as met in terrestrial and astrophysical plasmas.
- [87] arXiv:2005.08765 (cross-list from physics.ins-det) [pdf, ps, other]
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Title: A method to measure superconducting transition temperature of microwave kinetic inductance detector by changing power of readout microwavesAuthors: Hiroki Kutsuma, Yoshinori Sueno, Makoto Hattori, Satoru Mima, Shugo Oguri, Chiko Otani, Junya Suzuki, Osamu TajimaComments: 4 pages, 5 figuresSubjects: Instrumentation and Detectors (physics.ins-det); Instrumentation and Methods for Astrophysics (astro-ph.IM)
A microwave kinetic inductance detector (MKID) is a cutting-edge superconducting detector, and its principle is based on a superconducting resonator circuit. The superconducting transition temperature (Tc) of the MKID is an important parameter because various MKID characterization parameters depend on it. In this paper, we propose a method to measure the Tc of the MKID by changing the applied power of the readout microwaves. A small fraction of the readout power is deposited in the MKID, and the number of quasiparticles in the MKID increases with this power. Furthermore, the quasiparticle lifetime decreases with the number of quasiparticles. Therefore, we can measure the relation between the quasiparticle lifetime and the detector response by rapidly varying the readout power. From this relation, we estimate the intrinsic quasiparticle lifetime. This lifetime is theoretically modeled by Tc, the physical temperature of the MKID device, and other known parameters. We obtain Tc by comparing the measured lifetime with that acquired using the theoretical model. Using an MKID fabricated with aluminum, we demonstrate this method at a 0.3 K operation. The results are consistent with those obtained by Tc measured by monitoring the transmittance of the readout microwaves with the variation in the device temperature. The method proposed in this paper is applicable to other types, such as a hybrid-type MKID.
- [88] arXiv:2005.08783 (cross-list from gr-qc) [pdf, other]
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Title: Equation of states in the curved spacetime of spherical degenerate starsComments: 5 pages, 2 figuresSubjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Theory (hep-th)
In the study of spherical degenerate stars such as neutron stars, general relativistic effects are incorporated by using Tolman-Oppenheimer-Volkoff equations to describe their interior spacetime. However, the equation of states employed in such studies are invariably computed in flat spacetime. We show that the equation of states computed in the curved spacetime of these stars depend explicitly on the metric function. Further, we show that ignoring such metric-dependent gravitational time dilation effect leads one to grossly underestimate the mass limits of these compact stars. In turns, it provides a natural way to alleviate the so-called hyperon puzzle of the neutron stars.
- [89] arXiv:2005.08784 (cross-list from gr-qc) [pdf, other]
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Title: Quantum signatures from Horava-Lifshitz cosmographyComments: 7 pages, 2 figuresSubjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Theory (hep-th)
In this letter, we propose an alternative cosmography by considering Horava-Lifshitz gravity as a model of quantum gravity to search for quantum effects at the cosmological level. For our analyses we consider current late universe surveys and a Gravitational Waves forecast from Einstein Telescope. We found naturally a non-flat scenario with $\Omega_k =-0.021^{+0.023}_{-0.029}$ with $H_0 = 71.904^{+1.406}_{-1.347}$, without showing the standard reported $3.4$-$\sigma$ inconsistency. Furthermore, we obtained a specific value for the Horava parameter $\omega \approx -3.8\times 10^{-14}$, which can be interpreted as a measure of a quantum effect and could be used to further test this quantum gravity model. We conclude that classically, according to the $\Lambda$CDM model, our universe seems to be spatially flat, but in fact, it is curved from a quantum point of view.
- [90] arXiv:2005.08815 (cross-list from physics.plasm-ph) [pdf, other]
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Title: A Detailed Examination of Anisotropy and Timescales inThree-dimensional Incompressible Magnetohydrodynamic TurbulenceComments: In Press at Physics of PlasmasSubjects: Plasma Physics (physics.plasm-ph); Solar and Stellar Astrophysics (astro-ph.SR); Computational Physics (physics.comp-ph); Fluid Dynamics (physics.flu-dyn); Space Physics (physics.space-ph)
When magnetohydrodynamic turbulence evolves in the presence of a large-scale mean magnetic field, an anisotropy develops relative to that preferred direction. The well-known tendency is to develop stronger gradients perpendicular to the magnetic field, relative to the direction along the field. This anisotropy of the spectrum is deeply connected with anisotropy of estimated timescales for dynamical processes, and requires reconsideration of basic issues such as scale locality and spectral transfer. Here analysis of high-resolution three-dimensional simulations of unforced magnetohydrodynamic turbulence permits quantitative assessment of the behavior of theoretically relevant timescales in Fourier wavevector space. We discuss the distribution of nonlinear times, Alfv\'en times, and estimated spectral transfer rates. Attention is called to the potential significance of special regions of the spectrum, such as the two-dimensional limit and the "critical balance" region. A formulation of estimated spectral transfer in terms of a suppression factor supports a conclusion that the quasi two-dimensional fluctuations (characterized by strong nonlinearities) are not a singular limit, but may be in general expected to make important contributions.
- [91] arXiv:2005.08824 (cross-list from hep-ph) [pdf, other]
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Title: Searching for low mass dark matter via phonon creation in superfluid 4HeComments: 17 pages, 12 figuresSubjects: High Energy Physics - Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO); Other Condensed Matter (cond-mat.other); Superconductivity (cond-mat.supr-con)
We consider the scattering of dark matter particles from superfluid liquid $^4$He, which has been proposed as a target for their direct detection. Focusing on dark matter masses below ~1 MeV, we demonstrate from sum-rule arguments that for momentum transfers of interest the dominant process is the creation of a single phonon, with the direct creation of two or more phonons much less likely. We show further that the anomalous dispersion of phonons in liquid $^4$He at low pressures [i.e., $d^2\omega (q)/dq^2 > 0$, where $q$ and $\omega(q)$ are the phonon momentum and energy] has the important consequence that a single phonon will decay over a relatively short distance into a shower of lower energy phonons centered on the direction of the original phonon. Thus the experimental challenge in this regime is to detect a shower of low energy phonons, not just a single phonon. Additional information from the distribution of phonons in such a shower could enhance the determination of the dark matter mass.
- [92] arXiv:2005.08876 (cross-list from physics.plasm-ph) [pdf, other]
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Title: The effects of density inhomogeneities on the radio wave emission in electron beam plasmasComments: 37 pages, 5 tables, 17 figuresSubjects: Plasma Physics (physics.plasm-ph); Solar and Stellar Astrophysics (astro-ph.SR); Computational Physics (physics.comp-ph)
Type III radio bursts are radio emissions associated with solar flares. They are considered to be caused by electron beams in the solar corona. Magnetic reconnection is a possible accelerator of electron beams in the course of solar flares which causes unstable distribution functions, and density inhomogeneities. The properties of radio emission by electron beams in such environment are, however, still poorly understood. We capture the non-linear kinetic plasma processes of radio emissions in such plasmas by utilizing fully-kinetic Particle-In-Cell (PIC) code numerical simulations. Our model takes into account initial velocity distribution functions as they are supposed to be created by magnetic reconnection. These velocity distribution functions allow two distinct mechanisms of radio wave emissions: plasma emissions due to plasma-wave interactions and so called electron cyclotron maser emissions (ECME) due to wave-particle interactions. Our most important finding is that the number of harmonics of Langmuir waves increases with the density inhomogeneities. The harmonics are generated by the interaction of beam-generated Langmuir waves and their harmonics. In addition, we also find evidence for transverse harmonic electromagnetic wave emissions due to a coalescence of beam-generated and fundamental Langmuir waves with a vanishing wavevector. We investigate the effects of density inhomogeneities on the conversion process of the free energy of the electron beams to electrostatic and electromagnetic waves and the frequency shift of electron resonances caused by perpendicular gradients in the beam velocity distribution function. Our findings explain the observation of Langmuir waves and their harmonics in solar radio bursts and of the observed frequency shifts in these emissions.
Replacements for Tue, 19 May 20
- [93] arXiv:0705.0825 (replaced) [pdf, ps, other]
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Title: Einstein's Theory of Gravity in the Presence of Pressure: A ReviewAuthors: Ram Gopal Vishwakarma (Zacatecas University)Comments: Title correctedSubjects: General Relativity and Quantum Cosmology (gr-qc); Astrophysics (astro-ph); High Energy Physics - Theory (hep-th)
- [94] arXiv:1806.09508 (replaced) [pdf, other]
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Title: Gamma-ray spectral modulations induced by photon-ALP-dark photon oscillationsComments: 12 pages, 3 figures. v3: realization of background dark photon gauge fields included; v4: PRD accepted version, figures updated, chi-square analysis presented in Sec. III, observational constraints revisited in Sec. IV C and DJournal-ref: Phys. Rev. D 101, 043007 (2020)Subjects: High Energy Physics - Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Astrophysical Phenomena (astro-ph.HE)
- [95] arXiv:1810.13124 (replaced) [pdf, other]
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Title: Chirality and magnetic configuration associated with two-ribbon solar flares: AR 10930 versus AR 11158Comments: 24 pages, 9 figures, 2 tables, AdSpR(2020)65:2828, doi:10.1016/j.asr.2020.03.034Journal-ref: Advances in Space Research 65 (2020) 2828-2845Subjects: Solar and Stellar Astrophysics (astro-ph.SR)
- [96] arXiv:1903.10660 (replaced) [pdf, other]
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Title: Radio follow-up of a candidate gamma-ray transient in the sky localization area of GW170608Authors: Kyle Artkop, Rachel Smith, Alessandra Corsi, Simona Giacintucci, Wendy M. Peters, Rosalba Perna, S. Bradley Cenko, Tracy E. ClarkeComments: 8 pages, 1 figure, 3 tables; version update to match the published oneSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
- [97] arXiv:1905.05261 (replaced) [pdf, ps, other]
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Title: Irregularities in the rate of generation of giant pulses from the Crab pulsar observed at 111 MHzComments: 21 pages, 13 figuresSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
- [98] arXiv:1905.09800 (replaced) [pdf, ps, other]
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Title: Gaussbock: Fast parallel-iterative cosmological parameter estimation with Bayesian nonparametricsComments: 19 pages, 10 figures, accepted for publication in ApJSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Instrumentation and Methods for Astrophysics (astro-ph.IM); Computation (stat.CO); Methodology (stat.ME)
- [99] arXiv:1908.10594 (replaced) [pdf, other]
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Title: Neutrino halo effect on collective neutrino oscillation in iron core-collapse supernova model of a 9.6 $M_{\odot}$ starAuthors: Masamichi Zaizen, John F. Cherry, Tomoya Takiwaki, Shunsaku Horiuchi, Kei Kotake, Hideyuki Umeda, Takashi YoshidaComments: 29 pages with 32 figures, Accepted for publication in JCAPSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Phenomenology (hep-ph)
- [100] arXiv:1909.01819 (replaced) [pdf, other]
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Title: Probing P and CP Violations on the Cosmological ColliderComments: 22 pages, 8 figures; v2:references added; v3:appendix added, small changes in the textJournal-ref: JHEP 04 (2020) 189Subjects: High Energy Physics - Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)
- [101] arXiv:1909.01982 (replaced) [pdf, other]
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Title: The Scale Factor Potential Approach to InflationComments: Accepted for Publishing in EPJCSubjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Theory (hep-th)
- [102] arXiv:1909.02630 (replaced) [pdf, other]
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Title: The globular cluster system of the Auriga simulationsAuthors: Timo L. R. Halbesma, Robert J. J. Grand, Facundo A. Gómez, Federico Marinacci, Rüdiger Pakmor, Wilma H. Trick, Philipp Busch, Simon D. M. WhiteComments: Accepted by MNRAS 2020 May 15. Received 2020 May 14; in original form 2019 September 5Subjects: Astrophysics of Galaxies (astro-ph.GA)
- [103] arXiv:1910.01104 (replaced) [pdf, other]
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Title: $k$-evolution: a relativistic N-body code for clustering dark energyComments: 38 pages, 19 figures. Final version, accepted for publication in JCAPJournal-ref: JCAP 12 (2019) 011Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); Computational Physics (physics.comp-ph)
- [104] arXiv:1910.01105 (replaced) [pdf, other]
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Title: Parametrising non-linear dark energy perturbationsComments: 18 pages, 8 figures. Updated to match version published in JCAPJournal-ref: JCAP 04(2020)039Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc)
- [105] arXiv:1910.05102 (replaced) [pdf, other]
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Title: Dynamo-based limit to the extent of a stable layer atop Earth's coreComments: 17 pages, 9 figures, 2 tables, accepted for publication in GJISubjects: Geophysics (physics.geo-ph); Earth and Planetary Astrophysics (astro-ph.EP); Fluid Dynamics (physics.flu-dyn)
- [106] arXiv:1910.12867 (replaced) [pdf, other]
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Title: Multi-resolution filtering: an empirical method for isolating faint, extended emission in Dragonfly data and other low resolution imagesAuthors: Pieter van Dokkum, Deborah Lokhorst, Shany Danieli, Jiaxuan Li, Allison Merritt, Roberto Abraham, Colleen Gilhuly, Johnny P. GrecoComments: Accepted for publication in PASP. The mrf Python package is at this https URLSubjects: Astrophysics of Galaxies (astro-ph.GA); Instrumentation and Methods for Astrophysics (astro-ph.IM)
- [107] arXiv:1911.07886 (replaced) [pdf, ps, other]
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Title: Fitting the nonlinear matter bispectrum by the Halofit approachAuthors: Ryuichi Takahashi, Takahiro Nishimichi, Toshiya Namikawa, Atsushi Taruya, Issha Kayo, Ken Osato, Yosuke Kobayashi, Masato ShirasakiComments: 23 pages, 15 figures; accepted for publication in ApJ; typos corrected; numerical codes of the fitting formula are available at this https URL (Python) and this http URL (C and Fortran)Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc)
- [108] arXiv:1912.01050 (replaced) [pdf, other]
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Title: Reionization history constraints from neural network based predictions of high-redshift quasar continuaJournal-ref: Monthly Notices of the Royal Astronomical Society, Volume 493, Issue 3, 2020Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA)
- [109] arXiv:1912.09738 (replaced) [pdf, other]
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Title: Radiation hydrodynamical simulations of eruptive mass Loss from progenitors of Type Ibn/IIn supernovaeComments: 10 pages, 16 figures, 2 tables, added references for section 1 and 4, added discussion in section 2 and 3, typos corrected, accepted for Astronomy and AstrophysicsJournal-ref: A&A 635, A127 (2020)Subjects: Solar and Stellar Astrophysics (astro-ph.SR); High Energy Astrophysical Phenomena (astro-ph.HE)
- [110] arXiv:2001.05473 (replaced) [pdf, other]
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Title: Metal enrichment in the circumgalactic medium and Lyα haloes around quasars at z $\sim$3Authors: Yucheng Guo (KIAA-PKU, KICC-Cambrige), Roberto Maiolino (KICC-Cambridge), Linhua Jiang (KIAA-PKU), Kenta Matsuoka, Tohru Nagao, Oli Luiz Dors, Michele Ginolfi, Nick Henden, Jake Bennett, Debora Sijacki, Ewald PuchweinComments: 24 pages, 17 figures, resubmitted after addressing referee's commentsSubjects: Astrophysics of Galaxies (astro-ph.GA)
- [111] arXiv:2001.07891 (replaced) [pdf, other]
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Title: Probing compact dark matter with gravitational wave fringes detected by the Einstein TelescopeComments: 6 pages, 3 figures, accepted by MNRASSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc)
- [112] arXiv:2002.01421 (replaced) [pdf, other]
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Title: Can magnetized turbulence set the mass scale of stars?Authors: David Guszejnov, Michael Y. Grudić, Philip F. Hopkins, Stella S. R. Offner, Claude-André Faucher-GiguèreComments: 18 pages, 15 figures, submitted to MNRASSubjects: Astrophysics of Galaxies (astro-ph.GA)
- [113] arXiv:2002.02975 (replaced) [pdf, other]
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Title: Gravitational-wave captures by intermediate-mass black holes in galactic nucleiComments: 10 pages, 5 figures, accepted by ApJSubjects: Astrophysics of Galaxies (astro-ph.GA); High Energy Astrophysical Phenomena (astro-ph.HE)
- [114] arXiv:2002.03818 (replaced) [pdf, other]
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Title: Molecular gas and star formation activity in LIRGs in intermediate redshift clustersAuthors: G. Castignani, P. Jablonka, F. Combes, C.P. Haines, T. Rawle, M. Jauzac, E. Egami, M. Krips, D. Spérone-Longin, M. Arnaud, S. García-Burillo, E. Schinnerer, F. BigielComments: 26 pages, 10 figures, 5 tables, accepted for publication in A&ASubjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
- [115] arXiv:2002.09496 (replaced) [pdf, other]
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Title: From birth associations to field stars: mapping the small-scale orbit distribution in the Galactic discAuthors: Johanna Coronado, Hans-Walter Rix, Wilma H. Trick, Kareem El-Badry, Jan Rybizki, Maosheng XiangComments: 16 pages, 13 figures. Accepted for publication in MNRASSubjects: Astrophysics of Galaxies (astro-ph.GA)
- [116] arXiv:2003.00013 (replaced) [pdf, other]
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Title: The ALPINE-ALMA [CII] Survey: Size of Individual Star-Forming Galaxies at z=4-6 and their Extended Halo StructureAuthors: S. Fujimoto, J. D. Silverman, Matthieu Bethermin, M. Ginolfi, G. C. Jones, O. Le Fèvre, M. Dessauges-Zavadsky, W. Rujopakarn, A. L. Faisst, Y. Fudamoto, P. Cassata, L. Morselli, R. Maiolino, D. Schaerer, P. Capak, L. Yan, L. Vallini, S. Toft, F. Loiacono, G. Zamorani, M. Talia, D. Narayanan, N. P. Hathi, B. C. Lemaux, Médéric Boquien, R. Amorin, E. Ibar, A. M. Koekemoer, H. Méndez-Hernández, Sandro Bardelli, D. Vergani, E. Zucca, M. Romano, A. CimattiComments: 21 pages, 11 figures, ApJ in pressSubjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
- [117] arXiv:2003.00286 (replaced) [pdf, other]
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Title: Probing Einstein-dilaton Gauss-Bonnet Gravity with the inspiral and ringdown of gravitational wavesComments: 12 pages, 4 figures; added a citation and DOISubjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE)
- [118] arXiv:2003.06733 (replaced) [pdf, other]
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Title: Kilonova Emission From Black Hole-Neutron Star Mergers. I. Viewing-Angle-Dependent LightcurvesAuthors: Jin-Ping Zhu, Yuan-Pei Yang, Liang-Duan Liu, Yan Huang, Bing Zhang, Zhuo Li, Yun-Wei Yu, He GaoComments: 44 pages, 19 figures, 3 tables, accepted for publication in ApJSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)
- [119] arXiv:2003.09292 (replaced) [pdf]
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Title: Sun-Heliosphere Observation-based Ionization Rates ModelComments: 24 pages, 14 figures, 2 tables; under review in The Astrophysical JournalSubjects: Space Physics (physics.space-ph); Solar and Stellar Astrophysics (astro-ph.SR)
- [120] arXiv:2004.07971 (replaced) [pdf, other]
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Title: Exoplanet System Kepler-2 with comparisons to Kepler-1 and 13Comments: Accepted by Astrophysics and Space Science. Corrected some figure references in textSubjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
- [121] arXiv:2004.09597 (replaced) [pdf, other]
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Title: Keck/NIRC2 $L$'-Band Imaging of Jovian-Mass Accreting Protoplanets around PDS 70Authors: Jason J. Wang, Sivan Ginzburg, Bin Ren, Nicole Wallack, Peter Gao, Dimitri Mawet, Charlotte Z. Bond, Sylvain Cetre, Peter Wizinowich, Robert J. De Rosa, Garreth Ruane, Michael C. Liu, Olivier Absil, Carlos Alvarez, Christoph Baranec, Élodie Choquet, Mark Chun, Denis Defrère, Jacques-Robert Delorme, Gaspard Duchêne, Pontus Forsberg, Andrea Ghez, Olivier Guyon, Donald N. B. Hall, Elsa Huby, Aïssa Jolivet, Rebecca Jensen-Clem, Nemanja Jovanovic, Mikael Karlsson, Scott Lilley, Keith Matthews, François Ménard, Tiffany Meshkat, Maxwell Millar-Blanchaer, Henry Ngo, Gilles Orban de Xivry, Christophe Pinte, Sam Ragland, Eugene Serabyn, Ernesto Vargas Catalán, Ji Wang, Ed Wetherell, Jonathan P. Williams, Marie Ygouf, Ben ZuckermanComments: 20 pages, 5 figures, Accepted to AJ. Updated author list from original versionSubjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
- [122] arXiv:2004.10105 (replaced) [pdf, other]
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Title: Probing the magnetic field in the GW170817 outflow using H.E.S.S. observationsAuthors: H.E.S.S. Collaboration: H. Abdalla, R. Adam, F. Aharonian, F. Ait Benkhali, E.O. Angüner, M. Arakawa, C. Arcaro, C. Armand, T. Armstrong, H. Ashkar, M. Backes, V. Baghmanyan, V. Barbosa-Martins, A. Barnacka, M. Barnard, Y. Becherini, D. Berge, K. Bernlöhr, R. Blackwell, M. Böttcher, C. Boisson, J. Bolmont, S. Bonnefoy, J. Bregeon, M. Breuhaus, F. Brun, P. Brun, M. Bryan, M. Büchele, T. Bulik, T. Bylund, S. Caroff, A. Carosi, S. Casanova, M. Cerruti, T. Chand, S. Chandra, A. Chen, G. Cotter, M. Curyło, I.D. Davids, J. Davies, C. Deil, J. Devin, P. deWilt, L. Dirson, A. Djannati-Ataï, A. Dmytriiev, A. Donath, V. Doroshenko, J. Dyks, K. Egberts, F. Eichhorn, G. Emery, J.-P. Ernenwein, S. Eschbach, K. Feijen, S. Fegan, A. Fiasson, G. Fontaine, S. Funk, M. Füßling, et al. (170 additional authors not shown)Comments: 7 pages, 2 figures, 1 tableJournal-ref: The Astrophysical Journal Letters, 894, L16, 2020Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
- [123] arXiv:2004.11379 (replaced) [pdf, other]
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Title: Impacts of Dust Grains Accelerated by Supernovae on the MoonComments: 4 pages, 2 figures; accepted for publication in ApJLSubjects: Earth and Planetary Astrophysics (astro-ph.EP)
- [124] arXiv:2004.14630 (replaced) [pdf, other]
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Title: HI filaments are cold and associated with dark molecular gas. HI4PI based estimates of the local diffuse CO-dark H2 distributionComments: 15 pages, 15 Figures, accepted for publication in A&A, minor corrections in version 2Subjects: Astrophysics of Galaxies (astro-ph.GA)
- [125] arXiv:2004.14909 (replaced) [pdf, other]
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Title: Transport coefficients of nucleon neutron star cores for various nuclear potentials within the Brueckner-Hartree-Fock approachComments: 18 pages; 17 figures; submitted to Phys. Rev. D. In v.2. misprints correctedSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
- [126] arXiv:2005.02285 (replaced) [pdf, ps, other]
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Title: Flattening of the tokamak current profile by a fast magnetic reconnection with implications for the solar coronaAuthors: Allen H BoozerComments: 4 pages, no figuresSubjects: Plasma Physics (physics.plasm-ph); Solar and Stellar Astrophysics (astro-ph.SR)
- [127] arXiv:2005.03801 (replaced) [pdf, ps, other]
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Title: Influence of Collisions with Hydrogen on Titanium Abundance Determinations in Cool StarsComments: Published in Astronomy LettersSubjects: Solar and Stellar Astrophysics (astro-ph.SR)
- [128] arXiv:2005.04874 (replaced) [pdf, other]
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Title: The SAMI Galaxy Survey: Gas velocity dispersions in low-$z$ star-forming galaxies and the drivers of turbulenceAuthors: Mathew R. Varidel, Scott M. Croom, Geraint F. Lewis, Deanne B. Fisher, Karl Glazebrook, Barbara Catinella, Luca Cortese, Mark R. Krumholz, Joss Bland-Hawthorn, Julia J. Bryant, Brent Groves, Sarah Brough, Christoph Federrath, Jon S. Lawrence, Nuria P. Lorente, Matt S. Owers, Samuel N. Richards, Ángel R. López-Sánchez, Sarah M. Sweet, Jesse van de Sande, Sam P. VaughanComments: 27 pages, 10 figures, accepted for MNRASSubjects: Astrophysics of Galaxies (astro-ph.GA)
- [129] arXiv:2005.05283 (replaced) [pdf, other]
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Title: Implications of a "Fast Radio Burst" from a Galactic MagnetarComments: 21 pages, 9 figures; submitted to ApJL; comments welcome!Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
- [130] arXiv:2005.05757 (replaced) [pdf, ps, other]
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Title: On causal structure of $4D$-Einstein-Gauss-Bonnet black holeAuthors: Naresh DadhichComments: 3 pages, no figures, References addedSubjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Theory (hep-th)
- [131] arXiv:2005.06178 (replaced) [pdf, other]
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Title: The optical polarization of the blazar PKS 2155$-$304 during an optical flare in 2010Comments: 8 pages, 9 figuresSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
- [132] arXiv:2005.06744 (replaced) [pdf, other]
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Title: N-body Simulations of Ring Formation Process around the Dwarf Planet HaumeaComments: 23 pages, 6 figures, 2 tables, accepted for publication in ApJSubjects: Earth and Planetary Astrophysics (astro-ph.EP)
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