Astrophysics
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New submissions for Wed, 15 Apr 20
- [1] arXiv:2004.06113 [pdf, other]
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Title: The molecular cloud lifecycleAuthors: Mélanie Chevance, J. M. Diederik Kruijssen, Enrique Vazquez-Semadeni, Fumitaka Nakamura, Ralf Klessen, Javier Ballesteros-Paredes, Shu-ichiro Inutsuka, Angela Adamo, Patrick HennebelleComments: 52 pages, 7 figures. To appear in Space Science Reviews (submitted February 1, 2020; accepted April 8, 2020), topical collection Star formationSubjects: Astrophysics of Galaxies (astro-ph.GA)
Giant molecular clouds (GMCs) and their stellar offspring are the building blocks of galaxies. The physical characteristics of GMCs and their evolution are tightly connected to galaxy evolution. The macroscopic properties of the interstellar medium propagate into the properties of GMCs condensing out of it, with correlations between e.g. the galactic and GMC scale gas pressures, surface densities and volume densities. That way, the galactic environment sets the initial conditions for star formation within GMCs. After the onset of massive star formation, stellar feedback from e.g. photoionisation, stellar winds, and supernovae eventually contributes to dispersing the parent cloud, depositing energy, momentum and metals into the surrounding medium, thereby changing the properties of galaxies. This cycling of matter between gas and stars, governed by star formation and feedback, is therefore a major driver of galaxy evolution. Much of the recent debate has focused on the durations of the various evolutionary phases that constitute this cycle in galaxies, and what these can teach us about the physical mechanisms driving the cycle. We review results from observational, theoretical, and numerical work to build a dynamical picture of the evolutionary lifecycle of GMC evolution, star formation, and feedback in galaxies.
- [2] arXiv:2004.06114 [pdf, other]
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Title: Warm Decaying Dark Matter and the Hubble TensionComments: 33 pages, 8 figuresSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph)
If a fraction of the dark matter is unstable and decays into dark radiation at around the time of matter-radiation equality, it could impact the expansion history of the universe in a way that helps to ameliorate the long-standing tension between the locally measured value of the Hubble constant and the value inferred from measurements of the cosmic microwave background and baryon acoustic oscillations (assuming standard $\Lambda$CDM cosmology). If this component of decaying dark matter is cold, however, it will modify the evolution of the gravitational potentials, leading to inconsistencies with these same data sets. With this in mind, we consider here a component of decaying warm dark matter, with a free-streaming length that is long enough to remain consistent with existing data. We study the background and perturbation evolution of warm decaying dark matter, and use cosmological data to constrain the mass, abundance and decay rate of such a particle. We find that a component of warm decaying dark matter can significantly reduce the tension between local and cosmological determinations of the Hubble constant.
- [3] arXiv:2004.06116 [pdf, other]
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Title: Observational Constraints on the Multiphase Nature of Outflows Using Large Spectroscopic Surveys at $z\sim$0Authors: Guido Roberts-BorsaniComments: 13 pages, 9 figures. Accepted for publication in MNRASSubjects: Astrophysics of Galaxies (astro-ph.GA)
Mass outflow rates and loading factors are typically used to infer the quenching potential of galactic-scale outflows. However, these generally rely on observations of a single gas phase which can severely underestimate the total ejected gas mass. To address this, we use observations of high mass ($\geqslant$10$^{10}$ M$_{\odot}$), normal star-forming galaxies at $z\sim$0 from the MaNGA, xCOLD GASS, xGASS and ALFALFA surveys and a stacking of NaD, H$\alpha$, CO(1-0) and HI 21cm tracers with the aim of placing constraints on an average, total mass outflow rate and loading factor. We find detections of outflows in both neutral and ionised gas tracers, with no detections in stacks of molecular or atomic gas emission. Modelling of the outflow components reveals velocities of $|$v$_{\text{NaD}}|$=131 km s$^{-1}$ and $|$v$_{\text{H}\alpha}|$=439 km s$^{-1}$ and outflow rates of $\dot{M}_{\text{NaD}}$=7.55 M$_{\odot}$yr$^{-1}$ and $\dot{M}_{\text{H}\alpha}$=0.10 M$_{\odot}$yr$^{-1}$ for neutral and ionised gas, respectively. Assuming a molecular/atomic outflow velocity of 200 km s$^{-1}$, we derive upper limits of $\dot{M}_{\text{CO}}<$19.43 M$_{\odot}$yr$^{-1}$ and $\dot{M}_{\text{HI}}<$26.72 M$_{\odot}$yr$^{-1}$ for the molecular and atomic gas, respectively. Combining the detections and upper limits, we find average total outflow rates of $\dot{M}_{\text{tot}}\lesssim$27 M$_{\odot}$yr$^{-1}$ and a loading factor of $\eta_{\text{tot}}\lesssim$6.39, with molecular gas likely contributing $\lesssim$72% of the total mass outflow rate, and neutral and ionised gas contributing $\sim$28% and $<$1%, respectively. Our results suggest that, to first order, a degree of quenching via ejective feedback could occur in normal galaxies when considering all gas phases, even in the absence of an AGN.
- [4] arXiv:2004.06118 [pdf, other]
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Title: Reliably predicting FIR lines from simulated galaxiesAuthors: Alessandro Lupi, Andrea Pallottini, Andrea Ferrara, Stefano Bovino, Stefano Carniani, Livia ValliniComments: 16 pages, 10 figures, 2 tables, submitted to MNRASSubjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
Far-infrared (FIR) emission lines are a powerful tool to investigate the properties of the interstellar medium, especially in high-redshift galaxies, where ALMA observations have provided unprecedented information. Interpreting such data with state-of-the-art cosmological simulations post-processed with CLOUDY, has provided insights on the internal structure and gas dynamics of these systems. However, no detailed investigation of the consistency and uncertainties of this kind of analysis has been performed to date. Here, we compare different approaches to estimate FIR line emission from state-of-the-art cosmological simulations, either with CLOUDY or with on-the-fly non-equilibrium chemistry. We find that [CII]$_{158\mu}$ predictions are robust. [OI] emission lines are instead model-dependent, as these lines are strongly affected by the thermodynamic state of the gas and non-equilibrium photoionisation effects. For the same reasons, [OI] lines represent an excellent ISM diagnostic. Future observations targeting these lines will be also crucial to constrain models.
- [5] arXiv:2004.06121 [pdf, other]
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Title: Galaxy pairs in the Sloan Digital Sky Survey -- XIV. Galaxy mergers do not lie on the Fundamental Metallicity RelationComments: 13 pages, 10 figures. Accepted for publication in MNRASSubjects: Astrophysics of Galaxies (astro-ph.GA)
In recent observational studies, star-forming galaxies have been shown to follow a relation often dubbed the fundamental metallicity relation (FMR). This relation links the stellar mass of a galaxy with its star formation rate (SFR) and its gas-phase metallicity. Specifically, the FMR predicts that galaxies, at a given stellar mass, exhibit lower metallicities for higher SFRs. This trend is qualitatively consistent with observations of galaxy pairs, which have been robustly shown to experience increasing gas-phase metallicity dilution and enhanced star formation activity with decreasing projected separation. In this work, we show that, despite the qualitative consistency with FMR expectations, the observed O/H dilution in galaxy pairs of the Sloan Digital Sky Survey is stronger than what is predicted by the FMR. We conclude that the evolutionary phase of galaxies interacting with companions is not encoded in the FMR, and thus, mergers constitute a clearly defined population of outliers. We find that galaxies in pairs are consistent with the FMR only when their separation is larger than 110 kpc. Finally, we also quantify the local environment of the pairs using the number of galaxy neighbours within $2\, \mathrm{Mpc}$, $N_2$, and the projected separation to the second closest galaxy, $r_2$. We find that pairs are more sensitive to a second companion than to the local galaxy density, displaying less elevated SFRs with smaller values of $r_2$.
- [6] arXiv:2004.06123 [pdf, ps, other]
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Title: Star formation traced by optical and millimeter hydrogen recombination lines and free-free emissions in the dusty merging galaxy NGC 3256 -- MUSE/VLT and ALMA synergyAuthors: Tomonari Michiyama, Daisuke Iono, Kouichiro Nakanishi, Junko Ueda, Toshiki Saito, Takuji Yamashita, Alberto Bolatto, Min YunComments: APJ acceptedSubjects: Astrophysics of Galaxies (astro-ph.GA)
A galaxy-galaxy merger and the subsequent triggering of starburst activity are fundamental processes linked to the morphological transformation of galaxies and the evolution of star formation across the history of the Universe. Both nuclear and disk-wide starbursts are assumed to occur during the merger process. However, quantifying both nuclear and disk-wide star formation activity is non-trivial because the nuclear starburst is dusty in the most active merging starburst galaxies. This paper presents a new approach to this problem: combining hydrogen recombination lines in optical, millimeter, and free-free emission. Using NGC~3256 as a case study, H$\beta$, H40$\alpha$, and free-free emissions are investigated using the Multi Unit Spectroscopic Explorer at the Very Large Telescope of the European Southern Observatory (MUSE/VLT) and the Atacama Large Millimeter/submillimeter Array (ALMA). The H$\beta$ image obtained by MUSE identifies star-forming regions outside the nuclear regions, suggesting a disk-wide starburst. In contrast, the H40$\alpha$ image obtained by ALMA identifies a nuclear starburst where optical lines are undetected due to dust extinction ($A_{\rm V}\sim25$). Combining both MUSE and ALMA observations, we conclude that the total SFR is $49\pm2~M_{\odot}$~yr$^{-1}$ and the contributions from nuclear and disk-wide starbursts are $\sim34~\%$ and $\sim66~\%$, respectively. This suggests the dominance of disk-wide star formation in NGC~3256. In addition, pixel-by-pixel analyses for disk-wide star-forming regions suggest that shock gas tracers (e.g., CH$_3$OH) are enhanced where gas depletion time ($\tau_{\rm gas}$=$M_{\rm gas}/SFR$) is long. This possibly means that merger-induced shocks regulate disk-wide star formation activities.
- [7] arXiv:2004.06124 [pdf, other]
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Title: The detailed structure and the onset of galaxy formation in low-mass gaseous dark matter haloesComments: Submitted for publication in MNRASSubjects: Astrophysics of Galaxies (astro-ph.GA)
We present a model for the formation of the first galaxies before and after the reionization of hydrogen in the early universe. In this model, galaxy formation can only take place in dark matter haloes whose mass exceeds a redshift-dependent critical value, which, before reionization, is equal (in the simplest case) to the mass at which atomic hydrogen cooling becomes effective and, after reionization, is equal to the mass above which gas cannot remain in hydrostatic equilibrium. We define the Halo Occupation Fraction (HOF) as the fraction of haloes that host a luminous galaxy as a function of halo mass. The HOF is established by the interplay between the evolution of the critical mass and the assembly history of haloes and depends on three factors: the minimum halo mass for galaxy formation before reionization, the redshift of reionization, and the intensity of the (evolving) external photoheating rate. Our fiducial model predicts a cutoff in the galaxy mass function at a present-day halo mass, $M_{200} \sim 3\times 10^{8} M_{\odot}$; 100\% occupation at $M_{200} > 5\times 10^9 M_{\odot}$; and a population of starless gaseous haloes of present-day mass in the range $10^{6} \lesssim M_{200} / M_{\odot}\lesssim 5\times 10^{9}$, in which the gas is in thermal equilibrium with the ultraviolet background radiation and in hydrostatic equilibrium in the gravitational potential of the halo. The transition between HOF = 0 and HOF=1 reflects the stochastic nature of halo mass growth. We explore how these characteristic masses vary with model assumptions and parameter values. The results of our model are in excellent agreement with cosmological hydrodynamic simulations of galaxy formation.
- [8] arXiv:2004.06126 [pdf, other]
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Title: Impact of transforming to Conformal Fermi Coordinates on Quasi-Single Field Non-GaussianityComments: 13 pages, 2 figuresSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph)
In general relativity predictions for observable quantities can be expressed in a coordinate independent way. Nonetheless it may be inconvenient to do so. Using a particular frame may be the easiest way to connect theoretical predictions to measurable quantities. For the cosmological curvature bispectrum such frame is described by the Conformal Fermi Coordinates. In single field inflation it was shown that going to this frame cancels the squeezed limit of the density perturbation bispectrum calculated in Global Coordinates. We explore this issue in quasi single field inflation when the curvaton mass and the curvaton-inflaton mixing are small. In this case, the contribution to the bispectrum from the coordinate transformation to Conformal Fermi Coordinates is of the same order as that from the inflaton-curvaton interaction term but does not cancel it.
- [9] arXiv:2004.06128 [pdf, other]
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Title: Simulating JWST deep extragalactic imaging surveys and physical parameter recoveryAuthors: O. B. Kauffmann, O. Le Fèvre, O. Ilbert, J. Chevallard, C. C. Williams, E. Curtis-Lake, L. Colina, P. G. Pérez-González, J. P. Pye, K. I. CaputiComments: 25 pages, 23 figures, 5 tables. Submitted to A&ASubjects: Astrophysics of Galaxies (astro-ph.GA)
We present a new prospective analysis of deep multi-band imaging with the James Webb Space Telescope (JWST). In this work, we investigate the recovery of high-redshift $5<z<12$ galaxies through extensive image simulations of accepted JWST programs such as CEERS in the EGS field and HUDF GTO. We introduce complete samples of $\sim300,000$ galaxies with stellar masses $\log(M_*/M_\odot)>6$ and redshifts $0<z<15$, as well as galactic stars, into realistic mock NIRCam, MIRI and HST images to properly describe the impact of source blending. We extract the photometry of the detected sources as in real images and estimate the physical properties of galaxies through spectral energy distribution fitting. We find that the photometric redshifts are primarily limited by the availability of blue-band and near-infrared medium-band imaging. The stellar masses and star-formation rates are recovered within $0.25$ and $0.3$ dex respectively, for galaxies with accurate photometric redshifts. Brown dwarfs contaminating the $z>5$ galaxy samples can be reduced to $<0.01$ arcmin$^{-2}$ with a limited impact on galaxy completeness. We investigate multiple high-redshift galaxy selection techniques and find the best compromise between completeness and purity at $5<z<10$ using the full redshift posterior probability distributions. In the EGS field, the galaxy completeness remains higher than $50\%$ for $m_\text{UV}<27.5$ sources at all redshifts, and the purity is maintained above $80$ and $60\%$ at $z\leq7$ and $10$ respectively. The faint-end slope of the galaxy UV luminosity function is recovered with a precision of $0.1-0.25$, and the cosmic star-formation rate density within $0.1$ dex. We argue in favor of additional observing programs covering larger areas to better constrain the bright end.
- [10] arXiv:2004.06131 [pdf, other]
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Title: Digging for relics of the past: the ancient and obscured bulge globular cluster NGC6256Authors: Mario Cadelano, Sara Saracino, Emanuele Dalessandro, Francesco R. Ferraro, Barbara Lanzoni, Davide Massari, Cristina Pallanca, Maurizio SalarisComments: Accepted for publication by ApJSubjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
We used a set of moderately-deep and high-resolution optical observations obtained with the Hubble Space Telescope to investigate the properties of the stellar population in the heavily obscured bulge globular cluster NGC 6256. The analysis of the color-magnitude diagram revealed a stellar population with an extended blue horizontal branch and severely affected by differential reddening, which was corrected taking into account color excess variations up to \delta E(B-V) ~ 0.51. We implemented a Monte Carlo Markov Chain technique to perform the isochrone fitting of the observed color-magnitude diagram in order to derive the stellar age, the cluster distance and the average color excess in the cluster direction. Using different set of isochrones we found that NGC 6256 is characterized by a very old stellar age around 13.0 Gyr, with a typical uncertainty of ~ 0.5 Gyr. We also found an average color excess E(B-V) = 1.19 and a distance from the Sun of 6.8 kpc. We then derived the cluster gravitational center and measured its absolute proper motion using the Gaia-DR2 catalog. All this was used to back-integrate the cluster orbit in a Galaxy-like potential and measure its integrals of motion. It turned out that NGC 6256 is currently in a low-eccentricity orbit entirely confined within the bulge and its integrals of motion are fully compatible with a cluster purely belonging to the Galaxy native globular cluster population. All these pieces of evidence suggest that NGC 6256 is an extremely old relic of the past history of the Galaxy, formed during the very first stages of its assembly.
- [11] arXiv:2004.06132 [pdf, other]
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Title: Ejective and preventative: the IllustrisTNG black hole feedback and its effects on the thermodynamics of the gas within and around galaxiesAuthors: Elad Zinger (1), Annalisa Pillepich (1), Dylan Nelson (2), Rainer Weinberger (3), Rüdiger Pakmor (2), Volker Springel (2), Lars Hernquist (3), Federico Marinacci (4), Mark Vogelsberger (5) ( (1) Max-Planck-Institut für Astronomie, (2) Max-Planck-Institut für Astrophysik, (3) Institute for Theory and Computation, Harvard-Smithsonian Center for Astrophysics, (4) Department of Physics & Astronomy, University of Bologna, (5) Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology)Comments: Submitted to MNRAS. Comments welcomeSubjects: Astrophysics of Galaxies (astro-ph.GA)
Supermassive black holes (SMBHs) which reside at the centres of galaxies can inject vast amounts of energy into the surrounding gas and are thought to be a viable mechanism to quench star-formation in massive galaxies. Here we study the $10^{9-12.5}\,\mathrm{M_\odot}$ stellar mass central galaxy population of the IllustrisTNG simulation, specifically the TNG100 and TNG300 volumes at $z=0$, and show how the three components - SMBH, galaxy, and circumgalactic medium (CGM) - are interconnected in their evolution. We find that gas entropy is a sensitive diagnostic of feedback injection. In particular, we demonstrate how the onset of the low-accretion BH feedback mode, realised in the IllustrisTNG model as a kinetic, BH-driven wind, leads not only to star-formation quenching at stellar masses $\gtrsim10^{10.5}\,\mathrm{M_\odot}$ but also to a change in thermodynamic properties of the (non-star-forming) gas, both within the galaxy and beyond. The IllustrisTNG kinetic feedback from SMBHs increases the average gas entropy, within the galaxy and in the CGM, lengthening typical gas cooling times from $10-100\, \mathrm{Myr}$ to $1-10\,\mathrm{Gyr}$, effectively ceasing ongoing star-formation and inhibiting radiative cooling and future gas accretion. In practice, the same AGN feedback channel is simultaneously `ejective' and `preventative' and leaves an imprint on the temperature, density, entropy, and cooling times also in the outer reaches of the gas halo, up to distances of several hundred kiloparsecs. In the IllustrisTNG model, a long-lasting quenching state can occur for a heterogeneous CGM, whereby the hot and dilute CGM gas of quiescent galaxies contains regions of low-entropy gas with short cooling times.
- [12] arXiv:2004.06137 [pdf, other]
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Title: Detectability of kilonovae in optical surveys: $post$-$mortem$ examination of the LVC O3 run follow-upComments: 11 pages, 10 figures, 3 tables, to be submitted to MNRAS, comments are welcomeSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
The detection of the binary neutron star merger GW170817 and the associated electromagnetic (EM) counterpart, the "kilonova" (kN) AT2017gfo, opened a new era in multi-messenger astronomy. However, despite many efforts, it has been proven very difficult to find additional EM counterparts to the many LIGO/Virgo compact binary merger candidates since then. We explore the sensitivity of ongoing optical surveys searching for kNe and propose ways to optimize the choices of filters and survey depth to boost the detection efficiency for these faint and fast-evolving transients. In particular, we use kN models to explore the dependence on ejecta mass, geometry, viewing angle, wavelength coverage and source distance. Considering that the O3 LIGO/Virgo binary neutron star merger candidates were at distances about 5 times further than GW170817, we find that efficient $gri$ counterpart search would require reaching a limiting magnitude $m_{\rm lim}=$ 23 mag, given the model phase-space. We conclude that kN searches during O3 were generally too shallow to observe optical counterparts, even under optimistic assumptions, thus providing a plausible explanation for the lack of detections.
- [13] arXiv:2004.06140 [pdf, ps, other]
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Title: Gaia DR2 colour-temperature relations based on infrared flux method resultsComments: 9 pages, 7 figures, 1 table, extended version of RNAAS 4 52 2020Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)
The ESA/Gaia mission is providing accurate and precise all-sky photometry. We combined effective temperatures derived, for a sample of dwarf and giant stars, by Gonzalez Hernandez \& Bonifacio (2009) using the Infrared Flux Method, with the photometry available from the second release of the ESA/Gaia mission. We provide colour-temperature relations for the broad-band colours (BP-RP), (BP-G), (G-RP), (G-K), (BP-K), (RP-K). These relations allow the exploitation of the all-sky Gaia DR2 photometry to obtain precise effective temperatures.
- [14] arXiv:2004.06157 [pdf, other]
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Title: First Images of the Protoplanetary Disk Around PDS 201Authors: Kevin Wagner, Jordan Stone, Ruobing Dong, Steve Ertel, Daniel Apai, David Doelman, Alexander Bohn, Joan Najita, Sean Brittain, Matthew Kenworthy, Miriam Keppler, Ryan Webster, Emily Mailhot, Frans SnikComments: Accepted for publication in AJSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP)
Scattered light imaging has revealed nearly a dozen circumstellar disks around young Herbig Ae/Be stars$-$enabling studies of structures in the upper disk layers as potential signs of on-going planet formation. We present the first images of the disk around the variable Herbig Ae star PDS 201 (V* V351 Ori), and an analysis of the images and spectral energy distribution through 3D Monte-Carlo radiative transfer simulations and forward modelling. The disk is detected in three datasets with LBTI/LMIRCam at the LBT, including direct observations in the $Ks$ and $L'$ filters, and an $L'$ observation with the 360$^\circ$ vector apodizing phase plate coronagraph. The scattered light disk extends to a very large radius of $\sim$250 au, which places it among the largest of such disks. Exterior to the disk, we establish detection limits on substellar companions down to $\sim$5 M$_{Jup}$ at $\gtrsim$1.5" ($\gtrsim$500 au), assuming the Baraffe et al. (2015) models. The images show a radial gap extending to $\sim$0.4" ($\sim$140 au at a distance of 340 pc) that is also evident in the spectral energy distribution. The large gap is a possible signpost of multiple high-mass giant planets at orbital distances ($\sim$60-100 au) that are unusually massive and widely-separated compared to those of planet populations previously inferred from protoplanetary disk substructures.
- [15] arXiv:2004.06170 [pdf, other]
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Title: Technical Comment on "The dark matter interpretation of the 3.5-keV line is inconsistent with blank-sky observations"Authors: Kevork N. AbazajianComments: 7 pages, 2 figures. To be submitted as a Technical Comment to the journal ScienceSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Phenomenology (hep-ph)
I show that model dependencies in the analysis by Dessert, Rodd & Safdi (2020) relax their claimed constraint by a factor of ~20. After including conservative model choices, the derived limits are comparable to or slightly better than limits from previous searches. Further model tests and expansion of the data energy may enhance or relax sensitivity of the methodology.
- [16] arXiv:2004.06186 [pdf, other]
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Title: Nanoflare Theory RevisitedSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); Plasma Physics (physics.plasm-ph)
Local magnetic reversals are an inseparable part of magnetohydrodynamic (MHD) turbulence whose collective outcome on an arbitrary scale in the inertial range may lead to a global stochastic reconnection event with a rate independent of small scale physics. We show that this picture is intimately related to the nanoflare theory of the solar corona. First, we argue that due to stochastic flux freezing, a generalized version of flux freezing in turbulence, the magnetic field follows the turbulent flow in a statistical sense. Bending and stretching an initially smooth field, therefore, the turbulence generally increases the magnetic spatial complexity. Strong magnetic shears associated with such a highly tangled field can trigger local reversals and field annihilations that convert magnetic energy into kinetic and thermal energy respectively. The former maintains the turbulence, which incidentally continues to entangle the field completing the cycle, while the latter enhances the heat generation in the dissipative range. We support this theoretical picture invoking recent analytical and numerical studies which suggest a correlation between magnetic complexity and magnetic energy dissipation. The amplification of multiple local, in-phase reversals by super-linear Richardson diffusion may initiate a global reconnection at larger scales, however, even in the absence of such a global stochastic reconnection, the small scale reversals will continue to interact with the turbulence. We employ conventional scaling laws of MHD turbulence to illustrate that these local events are indeed efficient in both enhancing the turbulence and generating heat. Finally, using an MHD numerical simulation, we show that the time evolution of the magnetic complexity is statistically correlated with the kinetic energy injection rate and/or magnetic-to-thermal energy conversion rate.
- [17] arXiv:2004.06210 [pdf, other]
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Title: Discretization and Filtering Effects on Black Hole Images Obtained with the Event Horizon TelescopeComments: ApJ, submittedSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc)
Interferometers, such as the Event Horizon Telescope (EHT), do not directly observe the images of sources but rather measure their Fourier components at discrete spatial frequencies up to a maximum value set by the longest baseline in the array. Construction of images from the Fourier components or analysis of them with high-resolution models requires careful treatment of fine source structure nominally beyond the array resolution. The primary EHT targets, Sgr A* and M87, are expected to have black-hole shadows with sharp edges and strongly filamentary emission from the surrounding plasma on scales much smaller than those probed by the currently largest baselines. We show that for aliasing not to affect images reconstructed with regularized maximum likelihood methods and model images that are directly compared to the data, the sampling of these images (i.e., their pixel spacing) needs to be significantly finer than the scale probed by the largest baseline in the array. Using GRMHD simulations of black-hole images, we estimate the maximum allowable pixel spacing to be approximately equal to (1/8)GM/c^2; for both of the primary EHT targets, this corresponds to an angular pixel size of <0.5 microarcseconds. With aliasing under control, we then advocate use of the second-order Butterworth filter with a cut-off scale equal to the maximum array baseline as optimal for visualizing the reconstructed images. In contrast to the traditional Gaussian filters, this Butterworth filter retains most of the power at the scales probed by the array while suppressing the fine image details for which no data exist.
- [18] arXiv:2004.06218 [pdf, other]
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Title: Precise mass and radius of a transiting super-Earth planet orbiting the M dwarf TOI-1235: a planet in the radius gap?Authors: P. Bluhm, R. Luque, N. Espinoza, E. Palle, J. A. Caballero, S. Dreizler, J. H. Livingston, S. Mathur, A. Quirrenbach, S. Stock, V. Van Eylen, G. Nowak, E. Lopez, Sz. Csizmadia, M. R. Zapatero Osorio, P. Schoefer, J. Lillo-Box, M. Oshagh, P. J. Amado, D. Barrado, V. J. S. Bejar, B. Cale, P. Chaturvedi, C. Cifuentes, W. D. Cochran, K. A. Collins, K. I. Collins, M. Cortes-Contreras, E. Diez Alonso, M. El Mufti, A. Ercolino, M. Fridlund, E. Gaidos, R. A. Garcia, E. Gonzalez-Alvarez, L. Gonzalez-Cuesta, P. Guerra, A.P. Hatzes, T. Henning, E. Herrero, D. Hidalgo, G. Isopi, S. V. Jeffers, J. M. Jenkins, E. L. N. Jensen, P. Kabath, J. Kemmer, J. Korth, D. Kossakowski, M. Kuerster, M. Lafarga, F. Mallia, D. Montes, J. C. Morales, M. Morales-Calderon, F. Murgas, N. Narita, P. Plavchan, V. M. Passegger, et al. (22 additional authors not shown)Comments: 16 pages, 9 figuresSubjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
We report the confirmation of a transiting planet around the bright, inactive M0.5 V star TOI-1235 (TYC 4384-1735-1, V = 11.5 mag), whose transit signal was detected in the photometric time series of Sectors 14, 20, and 21 of the TESS space mission. We confirm the planetary nature of the transit signal, which has a period of 3.44 d, by using precise radial velocity measurements with CARMENES and HARPS-N spectrographs. A comparison of the properties derived for TOI-1235 b's with theoretical models reveals that the planet has a rocky composition, with a bulk density slightly higher than Earth's. In particular, we measure a mass of M_p = 5.9+/-0.6 M_Earth and a radius of R_p = 1.69+/-0.08 R_Earth, which together result in a density of rho_p = 6.7+1.3-1.1 g/cm3. When compared with other well-characterized exoplanetary systems, the particular combination of planetary radius and mass puts our discovery in the radius gap, a transition region between rocky planets and planets with significant atmospheric envelopes, with few known members. While the exact location of the radius gap for M dwarfs is still a matter of debate, our results constrain it to be located at around 1.7 R_Earth or larger at the insolation levels received by TOI-1235 b (~60 S_Earth), which makes it an extremely interesting object for further studies of planet formation and atmospheric evolution.
- [19] arXiv:2004.06226 [pdf, other]
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Title: Classifying CMB time-ordered data through deep neural networksComments: 9 pages, 6 figuresSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Machine Learning (cs.LG)
The Cosmic Microwave Background (CMB) has been measured over a wide range of multipoles. Experiments with arc-minute resolution like the Atacama Cosmology Telescope (ACT) have contributed to the measurement of primary and secondary anisotropies, leading to remarkable scientific discoveries. Such findings require careful data selection in order to remove poorly-behaved detectors and unwanted contaminants. The current data classification methodology used by ACT relies on several statistical parameters that are assessed and fine-tuned by an expert. This method is highly time-consuming and band or season-specific, which makes it less scalable and efficient for future CMB experiments. In this work, we propose a supervised machine learning model to classify detectors of CMB experiments. The model corresponds to a deep convolutional neural network. We tested our method on real ACT data, using the 2008 season, 148 GHz, as training set with labels provided by the ACT data selection software. The model learns to classify time-streams starting directly from the raw data. For the season and frequency considered during the training, we find that our classifier reaches a precision of 99.8%. For 220 and 280 GHz data, season 2008, we obtained 99.4% and 97.5% of precision, respectively. Finally, we performed a cross-season test over 148 GHz data from 2009 and 2010 for which our model reaches a precision of 99.8% and 99.5%, respectively. Our model is about 10x faster than the current pipeline, making it potentially suitable for real-time implementations.
- [20] arXiv:2004.06234 [pdf, other]
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Title: Light curves of tidal disruption events in active galactic nucleiComments: 7 pages, 5 figures, 1 appendix, submitted to ApJSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
The black hole of an active galactic nucleus is encircled by an accretion disk. The surface density of the disk is always too low to affect the tidal disruption of a star, but it can be high enough that a vigorous interaction results when the debris stream returns to pericenter and punches through the disk. Shocks excited in the disk dissipate the kinetic energy of the disk interior to the impact point and expedite inflow toward the black hole. Radiatively efficient disks with luminosity $\gtrsim10^{-3}$ Eddington have high enough surface density that the initial stream-disk interaction leads to energy dissipation at a super-Eddington rate. Because of the rapid inflow, only part of this dissipated energy emerges as radiation, while the rest is advected into the black hole. Dissipation, inflow, and cooling balance to keep the bolometric luminosity at an Eddington-level plateau that lasts tens of days. After the plateau, the luminosity decreases in proportion to the disk surface density, with a power-law index between $-3$ and $-2$ at earlier times, and possibly a steeper index at later times.
- [21] arXiv:2004.06245 [pdf, other]
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Title: The BACCO Simulation Project: Exploiting the full power of large-scale structure for cosmologyAuthors: Raul E. Angulo, Matteo Zennaro, Sergio Contreras, Giovanni Aricò, Marcos Pellejero-Ibañez, Jens Stücker (DIPC)Comments: 12 pages; 11 figuresSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA)
We present the BACCO project, a simulation framework specially designed to provide highly-accurate predictions for the distribution of mass, galaxies, and gas as a function of cosmological parameters. In this paper, we describe our main suite of simulations (L $\sim2$ Gpc and $4320^3$ particles) and present various validation tests. Using a cosmology-rescaling technique, we predict the nonlinear mass power spectrum over the redshift range 0 < z < 1.5 and over scales $10^{-2} < k/(h Mpc^{-1} ) < 5$ for 800 points in an 8-dimensional cosmological parameter space. For an efficient interpolation of the results, we build a Gaussian emulator which we test against other widely-used methods. Over the whole range of scales considered, we expect our predictions to be accurate at the 2% level for parameters in the minimal ${\Lambda}$CDM model and to 3% when extended to dynamical dark energy and massive neutrinos. We make our emulator publicly available under this http URL
- [22] arXiv:2004.06253 [pdf, ps, other]
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Title: Astrometric precision of centering algorithms based on model fittingSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
We provide a basis to select the optimal algorithm according to the specific observational conditions in ground-based astrometry, and clarify the loss of precision in the case of not achieving optimum. The principle of the centering algorithms based on model fitting is analyzed by the method of maximum likelihood. The effective point spread function (ePSF) algorithm, which can construct an accurate model to fit the star image, and the most widely used Gaussian centering algorithm are chosen to investigate the effect of different factors on centering precision. A series of synthetic star images with different backgrounds, full width at half maximums (FWHMs) and profiles are processed by these algorithms. The profiles include the actual profiles extracted from observations and the theoretical profiles, the spatial variation of the PSF across the detector is also taken into account. Each algorithm is applied to the observations obtained from Yunnan observatory to verify the simulation results. The simulations show that ePSF fitting is obviously more precise than Gaussian fitting for a Gaussian profile star with high signal-to-noise ratio (SNR). When the center of star profile becomes sharp, or the SNR of the star decreases, the advantage of ePSF fitting will gradually decrease. The high precision of ePSF fitting is due to its appropriate weight in the weighted least squares fitting. However, a similar method using the same weight, the weighted Gaussian fitting, turned out to be poor under some conditions. The reduction results of practical observations show good agree with the simulations. For a frame of CCD image with enough stars to construct accurate ePSFs, ePSF fitting can approach the Cramer-Rao (CR) bound. Other centering algorithms may achieve the same precision under suitable conditions, but will show poor precision when not used properly.
- [23] arXiv:2004.06256 [pdf, ps, other]
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Title: Hydrogenated Fullerenes (Fulleranes) in SpaceComments: 10 pages, 3 figures, invited review article for a special issue of Astrophys. Space Sci. devoted to "Unexplained Spectral Phenomena in the ISM"Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)
Since the first laboratory synthesis of C$_{60}$ in 1985, fullerene-related species have been proposed to interpret various astronomical features. After more than 25 years' efforts, several circumstellar and interstellar features have been convincingly assigned to C$_{60}$, C$_{70}$, and C$_{60}^+$. These successes resulted from the recent advancements in observational, experimental, as well as computational techniques, and re-stimulated interest in searching for fullerene derivatives in space. As one of the most important fullerene derivatives, hydrogenated fullerene (fullerane) is likely to exist in circumstellar and interstellar conditions. This review gives an overview of the chemical properties and spectral signals of fulleranes focusing on those relevant to astronomy. We summarize previous proposals of fulleranes as the carrier of astronomical features at UV, optical, infrared, and radio wavelengths, and discuss the arguments favoring or disfavoring the presence of fulleranes in astronomical environments. Although no unambiguous detection of fulleranes in space has yet been reported, there are plausible evidences for supporting the formation of certain fullerane isomers.
- [24] arXiv:2004.06265 [pdf, other]
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Title: On the Origin of an F-corona decrease revealed by the Parker Solar ProbeComments: 13 pages, 7 figures, to be submittedSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA); Space Physics (physics.space-ph)
The first-year results from the Parker Solar Probe (PSP) reveal a gradual decrease of F-coronal dust from distances of $D=0.166-0.336$ AU (or the inner elongations of $\sim 9.22- 18.69~R_{\odot}$) to the Sun, which cannot be explained by the dust sublimation scenario that predicts a dust-free-zone $\lesssim 4-5R_{\odot}$. In this paper, we attempt to explain this puzzle using our newly introduced mechanism of dust destruction so-called Radiative Torque Disruption (RATD) mechanism. We demonstrate that RATD rapidly breaks large grains into nanoparticles so that they can be efficiently destroyed by nonthermal sputtering induced by bombardment of energetic protons from slow solar winds. This joint effect extends the dust-free-zone established by thermal sublimation to $R_{dfz}\sim 8R_{\odot}$, which is called a new dust-free-zone. Beyond this new dust-free-zone, we find that the dust mass decreases gradually from $R\sim 42R_{\odot}$ toward the Sun due to partial removal of nanodust by nonthermal sputtering. This feature can successfully reproduce the gradual decrease of the F-corona between $19-9R_{\odot}$ observed by the PSP. Finally, the RATD mechanism can efficiently produce nanoparticles usually observed in the inner solar system.
- [25] arXiv:2004.06270 [pdf, other]
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Title: Pykat: Python package for modelling precision optical interferometersAuthors: Daniel D. Brown, Philip Jones, Samuel Rowlinson, Andreas Freise, Sean Leavey, Anna C. Green Daniel, ToyraSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Computational Physics (physics.comp-ph)
\textsc{Pykat} is a Python package which extends the popular optical interferometer modelling software \textsc{Finesse}. It provides a more modern and efficient user interface for conducting complex numerical simulations, as well as enabling the use of Python's extensive scientific software ecosystem. In this paper we highlight the relationship between \textsc{Pykat} and \textsc{Finesse}, how it is used, and provide an illustrative example of how it has helped to better understand the characteristics of the current generation of gravitational wave interferometers.
- [26] arXiv:2004.06352 [pdf, other]
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Title: Lenstool-HPC: A High Performance Computing based mass modelling tool for cluster-scale gravitational lensesComments: 9 pages + 4 appendix, publishedSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
With the upcoming generation of telescopes, cluster scale strong gravitational lenses will act as an increasingly relevant probe of cosmology and dark matter. The better resolved data produced by current and future facilities requires faster and more efficient lens modeling software.
Consequently, we present Lenstool-HPC, a strong gravitational lens modeling and map generation tool based on High Performance Computing (HPC) techniques and the renowned Lenstool software. We also showcase the HPC concepts needed for astronomers to increase computation speed through massively parallel execution on supercomputers.
Lenstool-HPC was developed using lens modelling algorithms with high amounts of parallelism. Each algorithm was implemented as a highly optimised CPU, GPU and Hybrid CPU-GPU version. The software was deployed and tested on the Piz Daint cluster of the Swiss National Supercomputing Centre (CSCS).
Lenstool-HPC perfectly parallel lens map generation and derivative computation achieves a factor 30 speed-up using only 1 GPUs compared to Lenstool. Lenstool-HPC hybrid Lens-model fit generation tested at Hubble Space Telescope precision is scalable up to 200 CPU-GPU nodes and is faster than Lenstool using only 4 CPU-GPU nodes. - [27] arXiv:2004.06359 [pdf, ps, other]
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Title: Trans-iron Ge, As, Se, and heavier elements in the dwarf metal-poor stars, HD~19445, HD~84937, HD~94028, HD~140283, and HD~160617Comments: Accepted by A&ASubjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)
Spectra of unevolved metal-poor halo stars uniquely reflect the elemental abundances incorporated during the earliest Galactic epoch. Their heavy-element content is well understood as the products of neutron capture on iron-peak elements. However, the lightest elements just past the iron peak, with atomic number 30<Z<52, show striking abundance patterns open to several interpretations. Understanding their nature may illuminate the diverse halo, thick disk, or extragalactic origins of metal-poor stars. For five metal-poor dwarfs, we analyzed high-resolution echelle UV spectra from the Hubble Space Telescope Imaging Spectrograph, as well as archival optical echelle spectra. The goal was to derive reliable halo dwarf abundances and uncertainties for six trans-iron elements from UV spectra, and optical abundances for four additional trans-Fe elements and two well-understood heavier elements. Our two independent analyses showed that the largest source of discrepancy is UV continuum placement. Once rectified, the internal results agree to 0.2 dex for moderately-unblended, moderately strong lines. Our results similarly agree with previous work, except where new data and unidentified Fe I lines are important. We show that these heavily congregate blueward of 2000A and redward of 2600A. Our exclusion of trans-Fe lines blended by such lines proved critical for arsenic. A metallicity-dependent odd-even effect is uncovered among trans-Fe elements: an odd-Z element abundance is depressed relative to those of adjacent even-Z elements, especially at low metallicity. This is supported by previous studies of Sr-Y-Zr, and also appears in some theoretical calculations. To date, no calculations predict the high Mo/Ge ratio, independent of Mo/Fe, that we find in all five stars.
- [28] arXiv:2004.06365 [pdf, other]
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Title: An updated discussion of the solar abundance problemComments: Prepared for the proceedings of 5th International Solar Neutrino ConferenceSubjects: Solar and Stellar Astrophysics (astro-ph.SR)
We discuss the level of agreement of a new generation of standard solar models (SSMs), Barcelona 2016 or B16 for short, with helioseismic and solar neutrino data, confirming that models implementing the AGSS09met surface abundances, based on refined three-dimensional hydrodynamical simulations of the solar atmosphere, do not not reproduce helioseismic constraints. We clarify that this solar abundance problem can be equally solved by a change of the composition and/or of the opacity of the solar plasma, since effects produced by variations of metal abundances are equivalent to those produced by suitable modifications of the solar opacity profile. We discuss the importance of neutrinos produced in the CNO cycle for removing the composition-opacity degeneracy and the perspectives for their future detection.
- [29] arXiv:2004.06396 [pdf]
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Title: Atmospheric Characterization via Broadband Color Filters on the PLAnetary Transits and Oscillations of stars (PLATO) MissionAuthors: John Lee Grenfell, Mareike Godolt, Juan Cabrera, Ludmila Carone, Antonio Garcia Munoz, Daniel Kitzmann, Alexis Smith, Heike RauerComments: accepted in Experimental Astronomy April 2020Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM); Solar and Stellar Astrophysics (astro-ph.SR)
We assess broadband color filters for the two fast cameras on the PLAnetary Transits and Oscillations (PLATO) of stars space mission with respect to exoplanetary atmospheric characterization. We focus on Ultra Hot Jupiters and Hot Jupiters placed 25pc and 100pc away from the Earth and low mass low density planets placed 10pc and 25pc away. Our analysis takes as input literature values for the difference in transit depth between the broadband lower (500 to 675nm) wavelength interval (hereafter referred to as blue) and the upper (675-1125nm) broadband wavelength interval (hereafter referred to as red) for transmission, occultation and phase curve analyses. Planets orbiting main sequence central stars with stellar classes F, G, K and M are investigated. We calculate the signal-to-noise ratio with respect to photon and instrument noise for detecting the difference in transit depth between the two spectral intervals. Results suggest that bulk atmospheric composition and planetary geometric albedos could be detected for (Ultra) Hot Jupiters up to about 100pc (about 25pc) with strong (moderate) Rayleigh extinction. Phase curve information could be extracted for Ultra Hot Jupiters orbiting K and G dwarf stars up to 25pc away. For low mass low density planets, basic atmospheric types (primary and water-dominated) and the presence of sub-micron hazes in the upper atmosphere could be distinguished for up to a handful of cases up to about 10pc.
- [30] arXiv:2004.06399 [pdf, other]
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Title: Joint growth rate measurements from redshift-space distortions and peculiar velocities in the 6dF Galaxy SurveyComments: 21 pages, 12 figures, 5 tablesSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
We present a new model for the cross-covariance between galaxy redshift-space distortions and peculiar velocities. We combine this with the auto-covariance models of both probes in a fully self-consistent, maximum-likelihood method, allowing us to extract enhanced cosmological parameter constraints. When applying our method to the 6-degree Field Galaxy Survey (6dFGS), our constraint on the growth rate of structure is $f\sigma_8 = 0.384 \pm 0.052 \rm{(stat)} \pm 0.061 \rm{(sys)}$ and our constraint for the redshift-space distortion parameter is $\beta = 0.289^{+0.044}_{-0.043} \rm{(stat)} \pm 0.049 \rm{(sys)}$. We find that the statistical uncertainty for the growth rate of structure is reduced by 64% when using the complete covariance model compared to the redshift-space distortion auto-covariance model and 50% when compared to using the peculiar velocity auto-covariance model. Our constraints are consistent with those from the literature on combining multiple tracers of large-scale structure, as well as those from other 6dFGS analyses. Our measurement is also consistent with the standard cosmological model.
- [31] arXiv:2004.06416 [pdf, other]
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Title: Relativistic X-ray jets from the black hole X-ray binary MAXI J1820+070Authors: Mathilde Espinasse, Stéphane Corbel, Philip Kaaret, Evangelia Tremou, Giulia Migliori, Richard M. Plotkin, Joe Bright, John Tomsick, Anastasios Tzioumis, Rob Fender, Jerome A. Orosz, Elena Gallo, Jeroen Homan, Peter G. Jonker, James C. A. Miller-Jones, David M. Russell, Sara MottaComments: Accepted for publication in ApJLSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
The black hole MAXI J1820+070 was discovered during its 2018 outburst and was extensively monitored across the electromagnetic spectrum. Following the detection of relativistic radio jets, we obtained four Chandra X-ray observations taken between 2018 November and 2019 May, along with radio observations conducted with the VLA and MeerKAT arrays. We report the discovery of X-ray sources associated with the radio jets moving at relativistic velocities with a possible deceleration at late times. The broadband spectra of the jets are consistent with synchrotron radiation from particles accelerated up to very high energies (>10 TeV) by shocks produced by the jets interacting with the interstellar medium. The minimal internal energy estimated from the X-ray observations for the jets is $\sim 10^{41}$ erg, significantly larger than the energy calculated from the radio flare alone, suggesting most of the energy is possibly not radiated at small scales but released through late-time interactions.
- [32] arXiv:2004.06419 [pdf, other]
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Title: Neutron Stars Merger RemnantsAuthors: Sebastiano BernuzziComments: 34 pages, 7 figures, 267 references. Invited review for the Topical Collection on Binary Neutron Star mergers of the journal General Relativity and Gravitation. First draft, comments welcomeSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc)
Binary neutron star mergers observations are a unique way to constrain fundamental physics and astrophysics at the extreme. The interpretation of gravitational-wave events and their electromagnetic counterparts crucially rely on general-relativistic models of the merger outcome and remnant properties. Quantitative models can be obtainted only with numerical relativity simulations in 3+1 dimensions that include detailed input physics for the nuclear matter and weak interactions. This review summarizes our current understanding of the merger's remnant focusing on some of the aspects that are relevant for multimessenger observations.
- [33] arXiv:2004.06449 [pdf, other]
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Title: H$_2$ content of galaxies inside and around intermediate redshift clustersAuthors: Damien Spérone-LonginComments: 5 pages, 4 figures, Proceedings of IAUS 359, Storchi-Bergmann et al. edSubjects: Astrophysics of Galaxies (astro-ph.GA)
Dense environments have an impact on the star formation rate of galaxies. As stars form from molecular gas, looking at the cold molecular gas content of a galaxy gives useful insights on its efficiency in forming stars. However, most galaxies observed in CO (a proxy for the cold molecular gas content) at intermediate redshifts, are field galaxies. Only a handful of studies focused on cluster galaxies. I present new results on the environment of one medium mass cluster from the EDisCS survey at $z\sim0.5$. 27 star-forming galaxies were selected to evenly sample the range of densities encountered inside and around the cluster. We cover a region extending as far as 8 virial radii from the cluster center. Indeed there are ample evidence that star formation quenching starts already beyond 3 cluster virial radius. I discuss our CO(3-2) ALMA observations, which unveil a large fraction of galaxies with low gas-to-stellar mass ratios.
- [34] arXiv:2004.06452 [pdf, ps, other]
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Title: On the Incidence Rate of Blazhko StarsAuthors: Geza KovacsComments: To appear in the Proceedings (ASP Conference Series) of the workshop "RRL/Cep 2019 - Frontiers of Classical Pulsators: Theory and Observations", 13-18 October 2019 Cloudcroft, New Mexico, USA; Editors: Karen Kinemuchi, Catherine Lovekin, Hilding Neilson, Kathy VivasSubjects: Solar and Stellar Astrophysics (astro-ph.SR)
In a recent paper (Kovacs 2018) we examined the incidence rate of the modulated RR Lyrae stars by using the data from Campaigns 01 - 04 of the Kepler K2 mission. We found an observed rate of ~90%, implying near 100% underlying rate, after correcting for detection bias due to observational noise. In this work we extend the sample to Campaign 08 and check the reliability of our earlier estimate. We get the same high rate, stressing the importance of full time series modelling (including systematics) in searching for shallow signals in the presence of large amplitude variabilities.
- [35] arXiv:2004.06457 [pdf, other]
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Title: A null test of the equivalence principle using relativistic effects in galaxy surveysComments: 29 pages, 7 figuresSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc)
The weak equivalence principle is one of the cornerstone of general relativity. Its validity has been tested with impressive precision in the Solar System, with experiments involving baryonic matter and light. However, on cosmological scales and when dark matter is concerned, the validity of this principle is still unknown. In this paper we construct a null test that probes the validity of the equivalence principle for dark matter. Our test has the strong advantage that it can be applied on data without relying on any modelling of the theory of gravity. It involves a combination of redshift-space distortions and relativistic effects in the galaxy number-count fluctuation, that vanishes if and only if the equivalence principle holds. We show that the null test is very insensitive to typical uncertainties in other cosmological parameters, including the magnification bias parameter, and to non-linear effects, making this a robust null test for modified gravity.
- [36] arXiv:2004.06476 [pdf, other]
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Title: A search for new $γ$-ray blazars from infrared selected candidatesComments: 3 pages, 2 figures, Proceedings paper of the IAU symposium "Nuclear Activity in Galaxies Across Cosmic Time" (Ethiopia) accepted to be published under the Cambridge University Press, eds. M. Povi\'c, P. Marziani, J. Masegosa, H. Netzer, S. H. Negu, and S. B. TessemaSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); Astrophysics of Galaxies (astro-ph.GA)
We present a systematic study of gamma-ray blazar candidates based on a sample of 40 objects taken from the WIBR catalogue. By using a likelihood analysis, 26 of the 40 sources showed significant gamma-ray signatures $\geq3\sigma$. Using high-energy test statistics (TS) maps, we confirm 8 sources, which are completely new, and show another 15 promising $\gamma$-ray candidates. The results from this analysis show that a multi-frequency approach can help to improve the current description of the gamma-ray sky.
- [37] arXiv:2004.06478 [pdf, other]
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Title: Offline and online reconstruction for radio interferometric imagingComments: 4 pages; 2 figures; URSI GASS 2020. arXiv admin note: substantial text overlap with arXiv:1712.04462Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
Radio astronomy is transitioning to a big-data era due to the emerging generation of radio interferometric (RI) telescopes, such as the Square Kilometre Array (SKA), which will acquire massive volumes of data. In this article we review methods proposed recently to resolve the ill-posed inverse problem of imaging the raw visibilities acquired by RI telescopes in the big-data scenario. We focus on the recently proposed online reconstruction method [4] and the considerable savings in data storage requirements and computational cost that it yields.
- [38] arXiv:2004.06486 [pdf, other]
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Title: Fast radio bursts from axion stars moving through pulsar magnetospheresComments: 8 pages, 3 figuresSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Phenomenology (hep-ph)
We study the radio signals generated when an axion star enters into the magnetosphere of a neutron star. As the axion star moves through the resonant region where the plasma-induced photon mass becomes equal to the axion mass, the axions can efficiently convert into photons, giving rise to an intense, transient radio signal. The energy released is determined by the axion star mass and conversion probability. Similarly, the peak frequency of the emitted radio signal is fixed by the axion mass, while cosmological redshift and Doppler shift could give rise to a wide range of frequencies. In particular, we show that a dense axion star with a mass $\sim 10^{-13}M_{\odot}$ composed of $\sim 10\: \mu$eV axions can account for most of the mysterious fast radio bursts in a wide frequency range.
- [39] arXiv:2004.06495 [pdf, other]
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Title: Cosmological Constraints on Scalar Field Dark MatterComments: 15 pages, 1 table and 2 figures. arXiv admin note: substantial text overlap with arXiv:1907.01033Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc)
This paper aims to put constraints on the parameters of the Scalar Field Dark Matter (SFDM) model, when dark matter is described by a free real scalar field filling the whole Universe, plus a cosmological constant term. By using a compilation of 51 $H(z)$ data and 1048 Supernovae data from Panteon, a lower limit for the mass of the scalar field was obtained, $m \geq 5.1\times 10^{-34} $eV and $H_0=69.5^{+2.0}_{-2.1}\text{ km s}^{-1}\text{Mpc}^{-1}$. Also, the present dark matter density parameter was obtained as $\Omega_\phi = 0.230^{+0.033}_{-0.031}$ at $2\sigma$ confidence level. The results are in good agreement to standard model of cosmology, showing that SFDM model is viable in describing the dark matter content of the universe.
- [40] arXiv:2004.06501 [pdf, other]
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Title: Dynamical cloud formation traced by atomic and molecular gasAuthors: H. Beuther, Y. Wang J. Soler, H. Linz, J. Henshaw, E. Vazquez-Semadeni, G. Gomez, S. Ragan, Th. Henning, S.C.O. Glover, M.-Y. Lee, R.GuestenComments: 13 pages, 15 figures, Astronomy & Astrophysics in press, a higher resolution version can be found at this http URLSubjects: Astrophysics of Galaxies (astro-ph.GA)
Context: Atomic and molecular cloud formation is a dynamical process. However, kinematic signatures of these processes are still observationally poorly constrained. Methods: Targeting the cloud-scale environment of the prototypical infrared dark cloud G28.3, we employ spectral line imaging observations of the two atomic lines HI and [CI] as well as molecular lines observations in 13CO in the 1--0 and 3--2 transitions. The analysis comprises investigations of the kinematic properties of the different tracers, estimates of the mass flow rates, velocity structure functions, a Histogram of Oriented Gradients (HOG) study as well as comparisons to simulations. Results: The central IRDC is embedded in a more diffuse envelope of cold neutral medium (CNM) traced by HI self-absorption (HISA) and molecular gas. The spectral line data as well as the HOG and structure function analysis indicate a possible kinematic decoupling of the HI from the other gas compounds. Spectral analysis and position-velocity diagrams reveal two velocity components that converge at the position of the IRDC. Estimated mass flow rates appear rather constant from the cloud edge toward the center. The velocity structure function analysis is consistent with gas flows being dominated by the formation of hierarchical structures. Conclusions: The observations and analysis are consistent with a picture where the IRDC G28 is formed at the center of two converging gas flows. While the approximately constant mass flow rates are consistent with a self-similar, gravitationally driven collapse of the cloud, external compression by, e.g., spiral arm shocks or supernovae explosions cannot be excluded yet. Future investigations should aim at differentiating the origin of such converging gas flows.
- [41] arXiv:2004.06528 [pdf, ps, other]
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Title: Planetary transits at radio wavelengths: secondary eclipses of hot Jupiter extended atmospheresComments: 9 pages, 3 figures, accepted for publication in The Astrophysical JournalSubjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM); Solar and Stellar Astrophysics (astro-ph.SR)
When a planet transits in front of its host star, a fraction of its light is blocked, decreasing the observed flux from the star. The same is expected to occur when observing the stellar radio flux. However, at radio wavelengths, the planet also radiates, depending on its temperature, and thus modifies the transit depths. We explore this scenario simulating the radio lightcurves of transits of hot-Jupiters, Kepler-17b and WASP-12b, around solar-like stars. We calculated the bremsstrahlung radio emission at 17, 100, and 400 GHz originated from the star, considering a solar atmospheric model. The planetary radio emission was calculated modelling the planets in two scenarios: as a blackbody or with a dense and hot extended atmosphere. In both cases the planet radiates and contributes to the total radio flux. For a blackbody planet, the transit depth is in the order of 2-4% and it is independent of the radio frequency. Hot-Jupiters planets with atmospheres appear bigger and brighter in radio, thus having a larger contribution to the total flux of the system. Therefore, the transit depths are larger than in the case of blackbody planets, reaching up to 8% at 17 GHz. Also the transit depth is frequency-dependent. Moreover, the transit caused by the planet passing behind the star is deeper than when the planet transits in front of the star, being as large as 18% at 400GHz. In all cases, the contribution of the planetary radio emission to the observed flux is evident when the planet transits behind the star.
- [42] arXiv:2004.06540 [pdf, other]
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Title: Observations of Galactic and Extragalactic NovaeComments: Invited review article for The Astronomy and Astrophysics Review. Comments and/or suggestions are welcome. 114 pages, 17 tables, 57 figuresSubjects: Solar and Stellar Astrophysics (astro-ph.SR); High Energy Astrophysical Phenomena (astro-ph.HE)
The recent GAIA DR2 measurements of distances to galactic novae have allowed to re-analyse some properties of nova populations in the Milky Way and in external galaxies on new and more solid empirical bases. In some cases we have been able to confirm results previously obtained, such as the concept of nova populations into two classes of objects, that is "disk" and "bulge" novae and their link with the Tololo spectroscopic classification in "Fe II" and "He/N" novae. The recent and robust estimates of nova rates in the Magellanic Clouds galaxies provided by the OGLE team have confirmed the dependence of the normalised nova rate (i.e. the nova rate per unit of luminosity of the host galaxy) with the colors and/or class of luminosity of the parent galaxies. The nova rates in the Milky Way and in external galaxies have been collected from literature and critically discussed. They are the necessary ingredient to assess the contribution of novae to the nucleosynthesis of the respective host galaxies, particularly to explain the origin of the overabundance of lithium observed in young stellar populations. A direct comparison between distances obtained via GAIA DR2 and Maximum Magnitude vs. Rate of Decline (MMRD) relationship points out that the MMRD can provide distances with an uncertainty better than 30%. Multi-wavelength observations of novae along the whole electromagnetic spectrum, from radio to gamma-rays, have revealed that novae undergo a complex evolution characterised by several emission phases and a non-spherical geometry for the nova ejecta.
- [43] arXiv:2004.06549 [pdf, ps, other]
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Title: High-energy and Very High-energy Constraints from Log-parabolic Spectral Models in Narrow-line Seyfert 1 GalaxiesAuthors: Stefano Vercellone (1), Luigi Foschini (1), Patrizia Romano (1), Markus Böttcher (2), Catherine Boisson (3) (1) INAF, Osservatorio Astronomico di Brera, Via Emilio Bianchi 46, I-23807 Merate (LC), Italy (2) Centre for Space Research, North-West University, Potchefstroom, 2531, South Africa (3) LUTH, Observatoire de Paris, CNRS, Universite Paris Diderot, PSL Research University Paris, 5 place Jules Janssen, F-92195 Meudon, FranceComments: 14 pages, 6 figures, 2 tables. Accepted for publication by Universe Special Issue "Seyfert Galaxies Astrophysics" on April 14 2020Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
Narrow-line Seyfert 1 galaxies (NLSy1s) are a well-established class of $\gamma$-ray sources, showing the presence of a jet like the more common flat-spectrum radio quasars. The evidence of $\gamma$-ray emission poses the issue of the location of the $\gamma$-ray emitting zone and of the contribution of the $\gamma$-$\gamma$ absorption within the broad-line region (BLR), since such objects have been detected by Fermi-LAT in the MeV-GeV energy range but not by imaging atmospheric Cherenkov telescopes beyond 100 GeV. We discuss how the spectral properties of three NLSy1s (SBS 0846+513, PMN J0948+0022, and PKS 1502+036) derived from the Fermi Large Area Telescope Fourth Source Catalog (4FGL) compare with theoretical models based on the observed properties of the BLR. In particular, we focus on the question on how simple power-law spectral models and log-parabolic ones could be disentangled in $\gamma$-ray narrow-line Seyfert 1 galaxies by means of current Fermi-LAT or future imaging atmospheric Cherenkov telescopes data. We find that the only possibility for a log-parabolic model to mimic a power-law model in the energy band above $E \sim 100$ GeV is to have a very small value of the curvature parameter $ \beta \sim 0.05$.
- [44] arXiv:2004.06556 [pdf, other]
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Title: Fundamental relations for the velocity dispersion of stars in the Milky WayAuthors: Sanjib Sharma, Michael R. Hayden, Joss Bland-Hawthorn, Dennis Stello, Sven Buder, Joel C. Zinn, Thomas Kallinger, Martin Asplund, Gayandhi M. De Silva, Valentina Dorazi, Ken Freeman, Janez Kos, Geraint F. Lewis, Jane Lin, Karin Lind, Sarah Martell, Jeffrey D. Simpson, Rob A. Wittenmyer, Daniel B. Zucker, Tomaz Zwitter, Boquan Chen, Klemen Cotar, James Esdaile, Marc Hon, Jonathan Horner, Daniel Huber, Prajwal R. Kafle, Shourya Khanna, Yuan-sen Ting, David M. Nataf, Thomas Nordlander, Mohd Hafiz Mohd Saadon, C. G. Tinney, Gregor Traven, Fred Watson, Duncan Wright, Rosemary F. G. WyseComments: 19 pages, 15 figures, submitted to MNRASSubjects: Astrophysics of Galaxies (astro-ph.GA)
We explore the fundamental relations governing the radial and vertical velocity dispersions of stars in the Milky Way, from combined studies of complementary surveys including GALAH, LAMOST, APOGEE, the NASA $Kepler$ and K2 missions, and $Gaia$ DR2. We find that different stellar samples, even though they target different tracer populations and employ a variety of age estimation techniques, follow the same set of fundamental relations. We provide the clearest evidence to date that, in addition to the well-known dependence on stellar age, the velocity dispersions of stars depend on orbital angular momentum $L_z$, metallicity and height above the plane $|z|$, and are well described by a multiplicatively separable functional form. The dispersions have a power-law dependence on age with exponents of 0.441$\pm 0.007$ and 0.251$\pm 0.006$ for $\sigma_z$ and $\sigma_R$ respectively, and the power law is valid even for the oldest stars. For the solar neighborhood stars, the apparent break in the power law for older stars, as seen in previous studies, is due to the anti-correlation of $L_z$ with age. The dispersions decrease with increasing $L_z$ until we reach the Sun's orbital angular momentum, after which $\sigma_z$ increases (implying flaring in the outer disc) while $\sigma_R$ flattens. The dispersions increase with decreasing metallicity, suggesting that the dispersions increase with birth radius. The dispersions also increase linearly with $|z|$. The same set of relations that work in the solar neighborhood also work for stars between $3<R/{\rm kpc}<20$. Finally, the high-[$\alpha$/Fe] stars follow the same relations as the low-[$\alpha$/Fe] stars.
- [45] arXiv:2004.06570 [pdf, ps, other]
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Title: Eccentricity distribution of wide low-mass binariesAuthors: Andrei TokovininComments: Submitted to MNRAS. 7 pages, 7 figures, 2 tablesSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP); Astrophysics of Galaxies (astro-ph.GA)
Distribution of eccentricities of very wide (up to 10 kau) low-mass binaries in the solar neighborhood is studied using the catalog of El-Badry and Rix (2018) based on Gaia. Direction and speed of relative motions in wide pairs contain statistical information on the eccentricity distribution, otherwise inaccessible owing to very long orbital periods. It is found that the eccentricity distribution is close to the linear (thermal) one f(e) = 2e$ However, pairs with projected separations <200 au have less eccentric orbits, while f(e) for very wide pairs appears to be slightly super-thermal, with an excess of very eccentric orbits. Eccentricity of any wide binary can be constrained statistically using direction and speed of its motion. Thermal eccentricity distribution signals an important role of stellar dynamics in the formation of wide binaries, although disk-assisted capture also can produce such pairs with eccentric orbits.
- [46] arXiv:2004.06589 [pdf, ps, other]
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Title: Constraints on Circumnuclear Disk through Free-Free Absorption in the Nucleus of 3C 84 with KaVA and KVN at 43 and 86 GHzComments: 10 pages, 4 figures, 2 tables, accepted for publication in ApJSubjects: Astrophysics of Galaxies (astro-ph.GA)
The nearby bright radio galaxy 3C 84 at the center of Perseus cluster is one of the ideal targets to explore the jet in active galactic nuclei (AGNs) and its parsec-scale environment. A recent research of Fujita & Nagai revealed the existence of the northern counter-jet component (N1) located at $\sim$ 2 mas north from the central core in VLBI images at 15 and 43 GHz and they are explained by the free-free absorption (FFA) due to an ionized plasma foreground. Here we report a new quasi-simultaneous observation of 3C 84 with the Korean VLBI Network (KVN) at 86 GHz and the KVN and VERA (VLBI Exploration of Radio Astrometry) Array (KaVA) at 43 GHz in 2016 February. We succeeded the first detection of N1 at 86 GHz and the data show that N1 still has an inverted spectrum between 43 and 86 GHz with its spectral index $\alpha$ ($S_{\nu} \propto \nu^{\alpha}$) of $1.19 \pm 0.43$, while the approaching lobe component has the steep spectrum with the index of $-0.54 \pm 0.30$. Based on the measured flux asymmetry between the counter and approaching lobes, we constrain the averaged number density of the FFA foreground $n_{\rm e}$ as $1.8 \times 10^{4}~{\rm cm^{-3}} \lesssim n_{\rm e} \lesssim 1.0 \times 10^{6}~{\rm cm^{-3}}$. Those results suggest that the observational properties of the FFA foreground can be explained by the dense ionized gas in the circumnuclear disk and/or assembly of clumpy clouds at the central $\sim 1$ pc region of 3C 84.
- [47] arXiv:2004.06600 [pdf, other]
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Title: Mapping the Galactic disk with the LAMOST and Gaia Red clump sample. VI: An evidence for the long lived non-steady warp of non-gravitational scenariosAuthors: H.-F. Wang, M. López-Corredoira, Y. Huang, J. Chang, H.-W. Zhang, J. L. Carlin, X.-D. Chen, Ž. Chrobáková, B.-Q. ChenComments: 12 pages, 6 figures, submitted and comments are welcomeSubjects: Astrophysics of Galaxies (astro-ph.GA)
By combining LAMOST DR4 and Gaia DR2 common red clump stars with age and proper motion, we analyze the amplitude evolution of the stellar warp independently of any assumption with a simple model. The greatest height of the warp disk increases with Galactocentric distance in different populations and it is dependent on the age: the younger stellar populations exhibit stronger warp features than the old ones, accompanied with the warp amplitude $\gamma ({\rm age})$ decreasing with age and its first derivative $\dot{\gamma} ({\rm age})$ is different from zero. The azimuth of line of nodes $\phi _w$ is stable at $-$5 degree without clear time evolution, which perfectly confirms some of previous works. All these self-consistent evidences support that our Galactic warp should most likely be a long lived, but non-steady structure and not a transient one, which is supporting the warp is originated from gas infall onto the disk or other hypotheses that suppose that the warp mainly affects to the gas, and consequently younger populations tracing the gas are stronger than the older ones. In other words, the Galactic warp is induced by the non-gravitational interaction over the disk models.
- [48] arXiv:2004.06601 [pdf, other]
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Title: Technical comment on the paper of Dessert et al. "The dark matter interpretation of the 3.5 keV line is inconsistent with blank-sky observations"Comments: Technical comment on the paper by Dessert et al. 10.1126/science.aaw3772Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Phenomenology (hep-ph)
An unidentified line at energy around 3.5 keV was detected in the spectra of dark matter-dominated objects. Recent work of Dessert et al. [1812.06976] used 30 Msec of XMM-Newton blank-sky observations to constrain the admissible line flux, challenging its dark matter decay origin. We demonstrate that these bounds are overestimated by more than an order of magnitude due to improper background modeling. Therefore the dark matter interpretation of the 3.5 keV signal remains viable.
- [49] arXiv:2004.06603 [pdf, other]
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Title: Measuring the cophasing state of a segmented mirror with a wavelength sweep and a Zernike phase contrast sensorAuthors: Anne-Laure Cheffot (1 and 2), Arthur Vigan (1), Samuel Leveque (2), Emmanuel Hugot (1) ((1) (Aix Marseille Univ, CNRS, CNES, LAM, Marseille, France),(2) European southern observatory)Comments: 23 pages, 14 figuresJournal-ref: Optics express Vol. 28, Issue 9, pp. 12566-12587 (2020)Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
The demand for higher resolution telescopes leads to segmented primary mirrors which need to be phased for operation. A phasing sensor applying a wavelength sweep technique provides a large capture range without modulating the position of individual mirror segments. This technique offers the potential to monitor the phasing state of a segmented telescope in parallel to the science observations. We evaluate the performance of the wavelength sweep technique using a Zernike phase contrast sensor for coarse phasing. Tests results on a dedicated bench show 112 nm rms precision. With the help of a simulation, we explain a known error of the method and we suggest ways for improvements.
- [50] arXiv:2004.06606 [pdf, ps, other]
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Title: Lithium in the closest satellite of our Milky WayComments: Proceedings of the conference "Lithium in the Universe: To Be or not to Be?", held at Rome Observatory, 18-22 November , 2019; in press for the Mem. Societ\`a Astronomica Italiana (4 pages and 3 figure)Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)
Recently, we studied the chemical evolution of lithium in the thin disc of the Milky Way. We found that the best agreement with the observed Li abundances in the thin disc is obtained considering novae as the main source of lithium. We assumed a delay time of ~1 Gyr for nova production and an effective 7Li yield of 1.8($\pm$0.6)x10$^{-5}$ Msun over the whole nova lifetime. The possibility to check our detailed assumptions on lithium production on other stellar systems, such as the satellites of our Milky Way, is seriously hampered by their distance from us. In these systems dwarf stars (where the original lithium can be measured) are too faint to detect lithium lines. However, thanks to the Gaia mission, it was recently possible to disentangle the stars of a disrupted dwarf galaxy in the Galactic halo (called Enceladus or Galactic sausage). Adopting a chemical evolution model tuned to match the metallicity distribution function of Enceladus stars, we present our predictions for the lithium abundance of the stars of this disrupted galaxy.
- [51] arXiv:2004.06616 [pdf, other]
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Title: Improved constraints on reionisation from CMB observations: A parameterisation of the kSZ effectComments: 12 pages, 10 figures. Submitted to A&ASubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
We show that, in the context of patchy reionisation, an accurate description of the angular power spectrum of the kinetic Sunyaev-Zel'dovich (kSZ) effect is not possible with simple scaling relations between the amplitude of the spectrum and global parameters such as the reionisation midpoint and its duration. We introduce a new parameterisation of this spectrum, based on a novel description of the power spectrum of the free electrons density contrast Pee(k,z) in terms of reionisation global history and morphology. We directly relate features of the spectrum to the typical ionised bubble size at different stages in the process, and subsequently to the angular scale at which the patchy kSZ power spectrum reaches its maximum. We successfully calibrate our results on a custom set of advanced radiative hydrodynamical simulations and later find our parameterisation to be a valid description of a wide range of other simulations and therefore reionisation physics. In the end, and as long as the global reionisation history is known, two parameters are sufficient to derive the angular power spectrum. Because of their straightforward physical interpretation, related to the morphology of reionisation, these parameters will be constrained by future 21cm intensity mapping experiments. Conversely, a precise measurement of the patchy kSZ power spectrum will constrain these parameters, and consequently the physics of reionisation. This parameterisation is therefore found to be an innovative tool to extract information about reionisation from CMB data.
- [52] arXiv:2004.06619 [pdf, other]
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Title: Multimessenger Cosmology: correlating CMB and SGWB measurementsAuthors: Peter Adshead, Niayesh Afshordi, Emanuela Dimastrogiovanni, Matteo Fasiello, Eugene A. Lim, Gianmassimo TasinatoComments: 5 pages, 2 figuresSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)
Characterizing the physical properties of the stochastic gravitational waves background (SGWB) is a key step towards identifying the nature of its possible origin. We focus our analysis on SGWB anisotropies. The existence of a non-trivial primordial scalar-tensor-tensor (STT) correlation in the squeezed configuration may be inferred from the effect that a long wavelength scalar mode has on the gravitational wave power spectrum: an anisotropic contribution. Crucially, such contribution is correlated with temperature anisotropies in the cosmic microwave background (CMB). We show that, for inflationary models that generate suitably large STT non-Gaussianities, cross-correlating the CMB with the stochastic background of gravitational waves is a very effective probe of early universe physics. The resulting signal can be a smoking-gun for primordial SGWB anisotropies.
- [53] arXiv:2004.06622 [pdf, other]
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Title: Two transiting hot Jupiters from the WASP survey: WASP-150b and WASP-176bAuthors: Benjamin F. Cooke, Don Pollacco, Y. Almleaky, K. Barkaoui, Z. Benkhaldoun, James A. Blake, François Bouchy, Panos Boumis, D. J. A. Brown, Ivan Bruni, A. Burdanov, Andrew Collier Cameron, Paul Chote, A. Daassou, Giuseppe D'ago, Shweta Dalal, Mario Damasso, L. Delrez, A. P. Doyle, E. Ducrot, M. Gillon, G. Hébrard, C. Hellier, Thomas Henning, E. Jehin, Flavien Kiefer, George W. King, Alexios Liakos, Théo Lopez, Luigi Mancini, Rosemary Mardling, P. F. L. Maxted, James McCormac, C. Murray, Louise D. Nielsen, Hugh Osborn, E. Palle, Francesco Pepe, F. J. Pozuelos, J. Prieto-Arranz, D. Queloz, Nicole Schanche, Damien Ségransan, Barry Smalley, John Southworth, S. Thompson, Oliver Turner, Stéphane Udry, S. Velasco, Richard West, Pete WheatleyComments: 15 pages, 14 figures. Accepted for publication in The Astronomical JournalSubjects: Earth and Planetary Astrophysics (astro-ph.EP)
We report the discovery of two transiting exoplanets from the WASP survey, WASP-150b and WASP-176b. WASP-150b is an eccentric ($e$ = 0.38) hot Jupiter on a 5.6 day orbit around a $V$ = 12.03, F8 main-sequence host. The host star has a mass and radius of 1.4 $\rm M_{\odot}$ and 1.7 $\rm R_{\odot}$ respectively. WASP-150b has a mass and radius of 8.5 $\rm M_J$ and 1.1 $\rm R_J$, leading to a large planetary bulk density of 6.4 $\rm \rho_J$. WASP-150b is found to be $\sim3$ Gyr old, well below its circularisation timescale, supporting the eccentric nature of the planet. WASP-176b is a hot Jupiter planet on a 3.9 day orbit around a $V$ = 12.01, F9 sub-giant host. The host star has a mass and radius of 1.3 $\rm M_{\odot}$ and 1.9 $\rm R_{\odot}$. WASP-176b has a mass and radius of 0.86 $\rm M_J$ and 1.5 $\rm R_J$ respectively, leading to a planetary bulk density of 0.23 $\rm \rho_J$.
- [54] arXiv:2004.06624 [pdf, ps, other]
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Title: Remarks on the well-posedness of the magnetic dynamo equationComments: 8 pages, no figuresSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
In the framework of astrophysical magnetic dynamos, we address the initial-value problem of the non-relativistic magnetic induction equation with an electromotive force at most linear in spatial derivatives of the magnetic field. We show that such a system turns out to be ill-posed when considering only a linear magnetic-field dependence on the force. This implies that there could be magnetic modes which may arbitrarily grow as frequency increases, despite any astrophysical dynamo mechanism. We then show that, when considering electromotive forces which are linear in magnetic field derivatives, the system turns out to be well-posed, and the magnetic energy is bounded by means of usual Sobolev inequalities. This last case constitutes, thus, a suitable scenario in which the growth of magnetic energy through physical magnetic modes is a good indicator of dynamo-like processes. Finally, we apply these results to the ``force-free dynamo'', firstly studying its constraint propagation, and deriving then estimates for the energy growth.
- [55] arXiv:2004.06631 [pdf, other]
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Title: Star Formation Occurs in Dense Gas, but What Does "Dense" Mean?Authors: Neal J. Evans II, Kee-Tae Kim, Jingwen Wu, Zhang Chao, Mark Heyer, Tie Liu, Quang Nguyen-Luong, Jens KauffmannComments: Accepted by the Astrophysical Journal,Subjects: Astrophysics of Galaxies (astro-ph.GA)
We report results of a project to map HCN and HCO+ J = 1-0 emission toward a sample of molecular clouds in the inner Galaxy, all containing dense clumps that are actively engaged in star formation. We compare these two molecular line tracers with millimeter continuum emission and extinction, as inferred from 13CO, as tracers of dense gas in molecular clouds. The fraction of the line luminosity from each tracer that comes from the dense gas, as measured by AV > 8 mag, varies substantially from cloud to cloud. In all cases, a substantial fraction (in most cases, the majority) of the total luminosity arises in gas below the AV > 8 mag threshold and outside the region of strong mm continuum emission. Measurements of the luminosity of HCN toward other galaxies will likely be dominated by such gas at lower surface density. Substantial, even dominant, contributions to the total line luminosity can arise in gas with densities typical of the cloud as a whole (densities about 100 per cubic cm). Defining the dense clump from the HCN or HCO+ emission itself, similarly to previous studies, leads to a wide range of clump properties, with some being considerably larger and less dense than in previous studies. HCN and HCO+ have similar ability to trace dense gas for the clouds in this sample. For the two clouds with low virial parameters, the 13CO is definitely a worse tracer of the dense gas, but for the other four, it is equally good (or bad) at tracing dense gas.
- [56] arXiv:2004.06681 [pdf, other]
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Title: A cryogenic ice setup to simulate carbon atom reactions in interstellar icesAuthors: D. Qasim, M.J.A. Witlox, G. Fedoseev, K.-J. Chuang, T. Banu, S.A. Krasnokutski, S. Ioppolo, J. Kastner, E.F. van Dishoeck, H. LinnartzComments: Accepted for publication in Review of Scientific InstrumentsSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)
The design, implementation, and performance of a customized carbon atom beam source for the purpose of investigating solid-state reaction routes in interstellar ices in molecular clouds are discussed. The source is integrated into an existing ultrahigh vacuum setup, SURFace REaction SImulation DEvice (SURFRESIDE$^{2}$), which extends this double atom (H/D, O, and N) beamline apparatus with a third atom (C) beamline to a unique system that is fully suited to explore complex organic molecule solid-state formation under representative interstellar cloud conditions. The parameter space for this system is discussed, which includes the flux of the carbon atoms hitting the ice sample, their temperature, and the potential impact of temperature on ice reactions. Much effort has been put into constraining the beam size to within the limits of the sample size with the aim to reduce carbon pollution inside the setup. How the C-atom beam performs is quantitatively studied through the example experiment, C + $^{18}$O$_2$, and supported by computationally-derived activation barriers. The potential for this source to study the solid-state formation of interstellar complex organic molecules through C-atom reactions is discussed.
- [57] arXiv:2004.06682 [pdf, other]
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Title: TOI-1235 b: a keystone super-Earth for testing radius valley emergence models around early M dwarfsAuthors: Ryan Cloutier, Joseph E. Rodriguez, Jonathan Irwin, David Charbonneau, Keivan G. Stassun, Annelies Mortier, David W. Latham, Howard Isaacson, Andrew W. Howard, Stéphane Udry, Thomas G. Wilson, Christopher A. Watson, Matteo Pinamonti, Florian Lienhard, Paolo Giacobbe, Pere Guerra, Karen A. Collins, Allyson Beiryla, Gilbert A. Esquerdo, Elisabeth Matthews, Ian J. M. Crossfield, Jennifer G. Winters, Chantanelle Nava, Kristo Ment, Eric D. Lopez, George Ricker, Roland Vanderspek, Sara Seager, Jon M. Jenkins, Eric B. Ting, Peter Tenenbaum, Alessandro Sozzetti, Lizhou Sha, Damien Ségransan, Joshua E. Schlieder, Dimitar Sasselov, Arpita Roy, Paul Robertson, Ken Rice, Ennio Poretti, Giampaolo Piotto, David Phillips, Joshua Pepper, Francesco Pepe, Emilio Molinari, Teo Mocnik, Giuseppina Micela, et al. (40 additional authors not shown)Comments: Submitted to AAS journals. 8 figures & 5 tables. Table 2 is provided in the arXiv source codeSubjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
Small planets on close-in orbits tend to exhibit envelope mass fractions of either effectively zero or up to a few percent depending on their size and orbital period. Models of thermally-driven atmospheric mass loss and of terrestrial planet formation in a gas-poor environment make distinct predictions regarding the location of this rocky/non-rocky transition in period-radius space. Here we present the confirmation of TOI-1235 b ($P=3.44$ days, $r_p=1.738^{+0.087}_{-0.076}$ R$_{\oplus}$), a planet whose size and period are intermediate between the competing model predictions, thus making the system an important test case for emergence models of the rocky/non-rocky transition around early M dwarfs ($R_s=0.630\pm 0.015$ R$_{\odot}$, $M_s=0.640\pm 0.016$ M$_{\odot}$). We confirm the TESS planet discovery using reconnaissance spectroscopy, ground-based photometry, high-resolution imaging, and a set of 38 precise radial-velocities from HARPS-N and HIRES. We measure a planet mass of $6.91^{+0.75}_{-0.85}$ M$_{\oplus}$ which implies an iron core mass fraction of $20^{+15}_{-12}$% in the absence of a gaseous envelope. The bulk composition of TOI-1235 b is therefore consistent with being Earth-like and we constrain a H/He envelope mass fraction to be $<0.5$% at 90% confidence. Our results are consistent with model predictions from thermally-driven atmospheric mass loss but not with gas-poor formation, which suggests that the former class of processes remain efficient at sculpting close-in planets around early M dwarfs. Our RV analysis also reveals a strong periodicity close to the first harmonic of the photometrically-determined stellar rotation period that we treat as stellar activity, despite other lines of evidence favoring a planetary origin ($P=21.8^{+0.9}_{-0.8}$ days, $m_p\sin{i}=13.0^{+3.8}_{-5.3}$ M$_{\oplus}$) that cannot be firmly ruled out by our data.
- [58] arXiv:2004.06685 [pdf, other]
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Title: Searching for the near infrared counterpart of Proxima c using multi-epoch high contrast SPHERE data at VLTAuthors: R. Gratton, A.Zurlo, H. Le Coroller, M. Damasso, F. Del Sordo, M. Langlois, D. Mesa, J. Milli, G. Chauvin, S. Desidera, J. Hagelberg, E. Lagadec, A. Vigan, A. Boccaletti, M. Bonnefoy, W. Brandner, S. Brown, F. Cantalloube, P. Delorme, V. D'Orazi, M. Feldt, R. Galicher, T. Henning, M. Janson, P. Kervella, A.M. Lagrange, C. Lazzoni, R. Ligi, A.-L. Maire, F. Menard, M. Meyer, L. Mugnier, A. Potier, E.L. Rickman, L. Rodet, C. Romero, T. Schmidt, E. Sissa, A. Sozzetti, J. Szulagyi, Z. Wahhaj, J. Antichi, T. Fusco, E. Stadler, M. Suarez, F. WildiComments: 14 pages, 5 figures. Accepted for publication on Astronomy and AstrophysicsSubjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM); Solar and Stellar Astrophysics (astro-ph.SR)
Proxima Centauri is known to host an earth-like planet in its habitable zone; very recently a second candidate planet was proposed based on radial velocities. At quadrature, the expected projected separation of this new candidate is larger than 1 arcsec, making it a potentially interesting target for direct imaging. While difficult, identification of the optical counterpart of this planet would allow detailed characterization of the closest planetary system. We searched for a counterpart in SPHERE images acquired during four years through the SHINE survey. In order to account for the large orbital motion of the planet, we used a method that assumes the circular orbit obtained from radial velocities and exploits the sequence of observations acquired close to quadrature in the orbit. We checked this with a more general approach that considers keplerian motion, K-stacker. We did not obtain a clear detection. The best candidate has S/N=6.1 in the combined image. A statistical test suggests that the probability that this detection is due to random fluctuation of noise is < 1% but this result depends on the assumption that distribution of noise is uniform over the image. The position of this candidate and the orientation of its orbital plane fit well with observations in the ALMA 12m array image. However, the astrometric signal expected from the orbit of the candidate we detected is 3-sigma away from the astrometric motion of Proxima as measured from early Gaia data. This, together with the unexpectedly high flux associated with our direct imaging detection, means we cannot confirm that our candidate is indeed Proxima c. On the other hand, if confirmed, this would be the first observation in imaging of a planet discovered from radial velocities and the second one (after Fomalhaut b) of reflecting circumplanetary material. Further confirmation observations should be done as soon as possible.
- [59] arXiv:2004.06707 [pdf, other]
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Title: Unbiased Cosmology Inference from Biased Tracers using the EFT LikelihoodComments: 31 pages, 9 figures, 2 tables; main results in Figs. 2, 4, 6; comments welcomeSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
We present updates on the cosmology inference using the effective field theory (EFT) likelihood presented previously in Schmidt et al., 2018, Elsner et al., 2019 [1,2]. Specifically, we add a cutoff to the initial conditions that serve as starting point for the matter forward model. We show that this cutoff, which was not employed in any previous related work, is important to regularize loop integrals that otherwise involve small-scale, non-perturbative modes. We then present results on the inferred value of the linear power spectrum normalization $\sigma_{8}$ from rest-frame halo catalogs using both second- and third-order bias expansions, imposing uniform priors on all bias parameters. Due to the perfect bias-$\sigma_{8}$ degeneracy at linear order, constraints on $\sigma_{8}$ rely entirely on nonlinear information. The results show the expected convergence behavior when lowering the cutoff in wavenumber, $\Lambda$. When including modes up to $k \leq \Lambda = 0.1\,h\,{\rm Mpc}^{-1}$ in the second-order case, $\sigma_{8}$ is recovered to within $\lesssim 6\,\%$ for a range of halo masses and redshifts. The systematic bias shrinks to $4\,\%$ or less for the third-order bias expansion on the same range of scales. Together with additional evidence we provide, this shows that the residual mismatch in $\sigma_{8}$ can be attributed to higher-order bias contributions. We conclude that the EFT likelihood is able to infer unbiased cosmological constraints, within expected theoretical systematic errors, from physical biased tracers on quasilinear scales
- [60] arXiv:2004.06709 [pdf, other]
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Title: Minimum size of cosmological 21-cm simulationsComments: 9 pages, 6 figures, submitted to MNRASSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA)
By mapping the large-scale thermal and ionization stucture of the intergalactic medium (IGM), cosmic 21-cm interferometry is set to revolutionize our understanding of the Epoch of Reionization (EoR) and the Cosmic Dawn (CD). However, interpreting upcoming observations relies on our ability to accurately model early galaxies and their cosmic radiation fields which drive the signal. The first galaxies are likely very rare and biased, with their abundances modulated by long wavelength modes of the density field. Moreover, the radiation fields from these galaxies interact with the IGM over a large range of scales. Therefore, the limited volume of 21-cm simulations can underestimate the amount of structure in the signal. In this work we quantify the minimum box size for simulating the power spectrum (PS) of the cosmic 21-cm signal. We perform multiple realizations of the initial conditions, for a range of box sizes. We quantify convergence with respect to a mock observation of box length 1.1 Gpc, with thermal noise computed for a 1000h observation with SKA1-low. We find that simulations of box lengths 200-300 Mpc typically do not show a bias in the PS during the EoR; however, they do tend to underestimate the large-scale power during the earlier epoch of CD by ~7-9 % on average. The absolute error on the PS from small-box realizations goes up to ~7 mK^2, or analogously up to ~4 sigma of the total noise. As expected, this bias and scatter between different realizations decreases with increasing box size. We conclude that box lengths of 250 Mpc are needed to converge at the level of <~1 sigma of the total noise.
Cross-lists for Wed, 15 Apr 20
- [61] arXiv:1901.10311 (cross-list from astro-ph.CO) [pdf]
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Title: Reaffirmation of Cosmological Oscillations in the Scale Factor from the Pantheon Compilation of 1048 Type Ia SupernovaeJournal-ref: MNRAS, April 10, 2020Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
We observe damped temporal oscillations in the scale factor at a dominant frequency of ~ 7 cycles/Hubble-time in the Pantheon Compilation of 1048 type Ia supernovae (SNe). The residual oscillations observed in the Pantheon data closely matches and reaffirms our initial observation of oscillations from earlier SNe data (primarily SNLS3, 2011) at 2-sigma confidence. The nearly identical shapes in amplitude, frequency, phase and damping constant makes it highly likely the signal is real. Furthermore, 2/3 of the Pantheon SNe cover different portions of the sky compared with SNLS3 strengthening this conclusion. Our model describing the oscillation, presented in an earlier paper, is a simple scalar field harmonic oscillator coupled to the LCDM Friedmann eqn, but carried into the present epoch. The scalar field energy density plays the role of the dark matter energy density in LCDM cosmology, fits well as an average, and closely matches the present dark matter density parameter, suggesting the oscillation play a role in the dark matter sector. Temporal oscillations in the scale factor and its derivative, as described in the present work, would also induce temporal oscillations of the Hubble parameter.
- [62] arXiv:2004.05342 (cross-list from gr-qc) [pdf, other]
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Title: Barotropic fluid compatible parametrizations of dark energyComments: 19 pages, 1 table, 4 figuresSubjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph)
Parametrizations of Equation of state parameter as a function of the scale factor or redshift are frequently used in dark energy modeling. The question investigated in this paper is if parametrizations proposed in the literature are compatible with the dark energy being a barotropic fluid. The test of this compatibility is based on the functional form of the speed of sound squared, which for barotropic fluid dark energy follows directly from the function for the Equation of state parameter. The requirement that the speed of sound squared should be between 0 and speed of light squared provides constraints on model parameters using analytical and numerical methods. It is found that this fundamental requirement eliminates a large number of parametrizations as barotropic fluid dark energy models and puts strong constraints on parameters of other dark energy parametrizations.
- [63] arXiv:2004.06155 (cross-list from gr-qc) [pdf, other]
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Title: Spherically symmetric static black holes in Einstein-aether theoryComments: revtex4, 9 figures, 6 tablesSubjects: General Relativity and Quantum Cosmology (gr-qc); Astrophysics of Galaxies (astro-ph.GA); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th)
In this paper, we systematically study spherically symmetric static spacetimes in the framework of Einstein-aether theory, and pay particular attention to the existence of black holes (BHs). In the theory, one scalar and one vector two gravitational modes additionally appear. To avoid the vacuum gravi-\v{C}erenkov radiation, they must all propagate with speeds greater than or at least equal to the speed of light. In the spherical case, only the scalar mode is relevant, so BH horizons are defined by this mode. In the present studies we first clarify several subtle issues. In particular, we find that, out of the five non-trivial field equations, only three are independent, so the problem is well-posed, as now there are only three unknown functions, two, $F(r)$ and $B(r)$, describe the spacetime and one, $A(r)$, describes the aether field. In addition, the two second-order differential equations for $A$ and $F$ are independent of $B$, and once they are found, $B$ is given simply by an algebraic expression of $F,\; A$ and their derivatives. To simplify the problem further, we explore the symmetry of field redefinitions, and work first with the redefined metric and aether field, and then obtain the physical ones by the inverse transformations. These clarifications significantly simplify the computational labor, which is important, as the problem is highly involved mathematically. In fact, it is exactly because of these, we find various numerical BH solutions with an accuracy that is at least two orders higher than previous ones. More important, these BH solutions are the only ones that satisfy the self-consistent conditions and meantime are consistent with all the observational constraints obtained so far. The locations of universal horizons are also identified, together with several other observationally interesting quantities.
- [64] arXiv:2004.06214 (cross-list from gr-qc) [pdf, other]
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Title: Holographic dark energy with non-minimal derivative coupling to gravity effectsAuthors: Chonticha Kritpetch (IF Naresuan), Candrasyah Muhammad (IF Naresuan), Burin Gumjudpai (IF Naresuan and ThEP Center)Comments: 11 pages, 12 figuresSubjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
Non-minimal derivative coupling (NMDC) to gravity in flat FLRW universe is investigated in the scenario of holographic dark energy. Kinetic term is coupled to the Einstein tensor under potential $V = (1/2)m^2 \phi^2$. The free kinetic term is allowed to be canonical and phantom. Gravitational constant is modified with the NMDC coupling. Holographic cutoff at Hubble horizon gives modification to dark energy density. We evaluate dark energy equation of state and the variation of gravitational constant of the theory such that the theory can be constrained. It is found that positive NMDC coupling is favored rather than the negative one. The model with purely NMDC theory and the potential is favored with positive sub-Planckian NMDC coupling and decaying scalar field. The canonical scalar field with positive NMDC coupling under the potential is also viable under some conditions that result in oscillating scalar field. The phantom field case is not favored in this model since the coupling and scalar mass are required to be super-Planckian while it is tightly constrained by gravitational constant variation observations.
- [65] arXiv:2004.06228 (cross-list from nlin.CD) [pdf, other]
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Title: Fractal basins of convergence of a seventh-order generalized Hénon-Heiles potentialComments: 11 pages, 8 figuresSubjects: Chaotic Dynamics (nlin.CD); Astrophysics of Galaxies (astro-ph.GA)
This article aims to investigate the points of equilibrium and the associated convergence basins in a seventh-order generalized H\'enon-Heiles potential. Using the well-known Newton-Raphson iterator we numerically locate the position of the points of equilibrium, while we also obtain their linear stability. Furthermore, we demonstrate how the two variable parameters, entering the generalized H\'enon-Heiles potential, affect the convergence dynamics of the system as well as the fractal degree of the basin diagrams. The fractal degree is derived by computing the (boundary) basin entropy as well as the uncertainty dimension.
- [66] arXiv:2004.06276 (cross-list from gr-qc) [pdf, other]
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Title: Quantum Black Hole Seismology II: Applications to Astrophysical Black HolesComments: 14 pages, 14 figures. NO and DT equally contributed to this work. To be submitted to a journal this weekend, comments welcomeSubjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE)
With the advent of gravitational wave astronomy, searching for gravitational wave echoes from black holes (BHs) is becoming an interesting probe of their quantum nature near their horizons. Newborn BHs may be strong emitters of echoes, as they accompany large perturbations in the surrounding spacetime upon formation. Utilizing the Quantum Black Hole Seismology framework (Oshita et al. 2020), we study the expected echoes upon BH formation resulting from neutron star mergers and failed supernovae. For BH remnants from neutron star mergers, we evaluate the consistency of these models with the recent claim on the existence of echoes following the neutron star merger event GW170817. We find that the claimed echoes in GW170817, if real, suggest that overtones contribute a significant amount of energy in the ringdown of the remnant BH. We finally discuss the detectability of echoes from failed supernovae by second and third-generation gravitational wave detectors, and find that current (future) detectors constrain physical reflectivity models for events occurring within a few Mpc (a few x 10 Mpc). Detecting such echo signals may significantly constrain the maximum mass and equation of state of neutron stars.
- [67] arXiv:2004.06287 (cross-list from physics.ins-det) [pdf, other]
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Title: Development of ultra-pure NaI(Tl) detector for COSINE-200 experimentAuthors: B.J. Park, J.J. Choe, J.S. Choi, O. Gileva, C. Ha, A. Iltis, E.J. Jeon, D.Y. Kim, K.W. Kim, S.K. Kim, Y.D. Kim, Y.J. Ko, C.H. Lee, H.S. Lee, I.S. Lee, M.H. Lee, S.H. Lee, S.J. Ra, J.K. Son, K.A. ShinComments: 11 pages 13 figuresSubjects: Instrumentation and Detectors (physics.ins-det); Instrumentation and Methods for Astrophysics (astro-ph.IM); High Energy Physics - Experiment (hep-ex); Nuclear Experiment (nucl-ex)
The annual modulation signal observed by the DAMA experiment is a long standing question in the community of dark matter direct detection. This necessitates an independent verification for its origin using the same detection technique. The COSINE-100 experiment has been operating with 106~kg of low-background NaI(Tl) detectors providing interesting checks for the DAMA signal. However, due to higher background in the NaI(Tl) crystals used in COSINE-100 relative to those used for DAMA, it was difficult to reach final conclusions. Since the start of COSINE-100 data taking in 2016, we also have initiated a program to develop ultra-pure NaI(Tl) crystals for COSINE-200, the next phase of the experiment. The program includes efforts of raw powder purification, ultra-pure NaI(Tl) crystal growth, and detector assembly. With extensive research and development of NaI(Tl) crystal growth, we have successfully grown a few Tl-doped crystals with high radio-purity. A high light yield has been achieved with our detector assembly technique. Here we report the ultra-pure NaI(Tl) detector developments at the Institute for Basic Science, Korea. The technique developed here will be applied to the production of ultra-pure NaI(Tl) detectors for the COSINE-200 experiment.
- [68] arXiv:2004.06437 (cross-list from hep-th) [pdf, other]
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Title: Ekpyrotic Cosmology with a Zero-Shear S-BraneComments: 8 pages, no figuresSubjects: 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)
In a recent paper we proposed a mechanism for a continuous transition between a contracting Ekpyrotic phase and the Standard Big Bang phase of expansion: the bounce is generated by an S-brane which represents the effects of higher mass string states in the low energy effective field theory. We showed that gravitational waves on cosmological scales obtain a nearly scale-invariant spectrum. Here, we study the cosmological fluctuations in this setup, assuming that the S-brane has zero shear. We find a nearly scale-invariant spectrum of cosmological perturbations with a slight red tilt. The scenario yields two consistency relations for cosmological observations, the first one relating the tensor to scalar ratio with the scalar spectral tilt, the second relating the tensor tilt to the scalar tilt. The predicted tensor to scalar ratio is within the reach of upcoming CMB observations. The tensor tilt is blue.
- [69] arXiv:2004.06466 (cross-list from gr-qc) [pdf, ps, other]
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Title: Coupled Multi-Proca Vector Dark EnergyAuthors: L. Gabriel Gomez (1), Yeinzon Rodriguez (1,2,3) ((1) Universidad Industrial de Santander, (2) Universidad Antonio Narino, (3) The Abdus Salam International Centre for Theoretical Physics)Comments: LaTeX file in RevTex 4.1 style, 13 pages in double column, 13 figuresSubjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
We study a new class of vector dark energy models where multi-Proca fields $A_\mu^a$ are coupled to cold dark matter by the term $f(X)\tilde{\mathcal{L}}_{m}$ where $f(X)$ is a general function of $X\equiv -\frac{1}{2}A^\mu_ a A^a_\mu$ and $\tilde{\mathcal{L}}_{m}$ is the cold dark matter Lagrangian. From here, we derive the general covariant form of the novel interaction term sourcing the field equations. This result is quite general in the sense that encompasses Abelian and non-Abelian vector fields. In particular, we investigate the effects of this type of coupling in a simple dark energy model based on three copies of canonical Maxwell fields to realize isotropic expansion. The cosmological background dynamics of the model is examined by means of a dynamical system analysis to determine the stability of the emergent cosmological solutions. As an interesting result, we find that the coupling function leads to the existence of a novel scaling solution during the dark matter dominance. Furthermore, the critical points show an early contribution of the vector field in the form of dark radiation and a stable de Sitter-type attractor at late times mimicking dark energy. The cosmological evolution of the system as well as the aforementioned features are verified by numerical computations. Observational constraints are also discussed to put the model in a more phenomenological context in the light of future observations.
- [70] arXiv:2004.06470 (cross-list from physics.pop-ph) [pdf]
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Title: Habitability is a continuous property of natureAuthors: René Heller (Max Planck Institute for Solar System Research, Göttingen, Germany)Comments: 1 col. figureJournal-ref: Nature Astronomy, 2020, Vol. 4, Issue 4, pp. 294-295Subjects: Popular Physics (physics.pop-ph); Earth and Planetary Astrophysics (astro-ph.EP); Biological Physics (physics.bio-ph)
In their recent comment, Cockell et al. argue that the habitability of an environment is fundamentally a binary property; that is to say, an environment can either support the metabolic processes of a given organism or not. The habitability of different environments, they argue, may have different degrees that could be determined at least in theory by answering the question: 'is this environment habitable to a given organism?' 'More' or 'less' habitable environments could then be related by the number of yes or no answers given to what is fundamentally a series of binary questions and decisions. In my opinion, there are at least three implicit assumptions made for this line of reasoning that are implausible and that sabotage the conclusions. The first is in the genetic diversity of the organisms, which I argue is fundamentally continuous in nature and a binary construction of the sample is not meaningful. The second misconception is in the assumption that an ecosystem can be decomposed into subsets of independent samples. The third problem is in the definition of an environment. The question of the environment is a continuous one in both space and time and thus any concept constructed to be applicable to a sample of environments must be continuous as well. In summary, the question of whether habitability is a binary quantity or not brings us back to the question of whether our concepts of life and of the environments that life thrives in (or not) are binary or non-binary. I argue that the latter is the case, and hence any modern concept of habitability must be continuous too.
- [71] arXiv:2004.06526 (cross-list from physics.comp-ph) [pdf, other]
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Title: Adaptive degenerate space method for source term estimation using a backward Lagrangian stochastic modelComments: 17 pages, 7 figuresSubjects: Computational Physics (physics.comp-ph); Instrumentation and Methods for Astrophysics (astro-ph.IM); Atmospheric and Oceanic Physics (physics.ao-ph); Fluid Dynamics (physics.flu-dyn); Geophysics (physics.geo-ph)
The general problem of characterizing gas source parameters based on concentration measurements is known to be a difficult task. As many inverse problems, one of the main obstacles for accurate estimation is the non-uniqueness of solution, induced by the lack of sufficient information. As the number of detectors is lowered, which is more than a plausible scenario for many practical situations, the number of possible solutions that can characterize the source increases dramatically, leading to severe errors. In this paper, a Lagrangian stochastic based method for identifying these suspected points, which will be referred to as 'degenerate space', is formulated and analysed. Then, a new procedure for quantitative prediction of the effect of deploying a new detector in space is used to design an adaptive scheme for source term estimation. This scheme has been tested for several scenarios, differing by the location of the initial detectors, and is shown to reduce dramatically the degeneracy formed by insufficient information. The combined formulation of degenerate space with the new adaptive scheme is shown to give improved accuracy, and in particular for a relatively small number of detectors.
- [72] arXiv:2004.06605 (cross-list from gr-qc) [pdf, ps, other]
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Title: Black hole and naked singularity geometries supported by three-form fieldsComments: 19 pages, 22 figuresSubjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Theory (hep-th)
We investigate static and spherically symmetric solutions in a gravity theory that extends the standard Hilbert-Einstein action with a Lagrangian constructed from a three-form field $A_{\alpha \beta \gamma}$, which is related to the field strength and a potential term. The field equations are derived from a variational principle and are obtained explicitly for a static and spherically symmetric geometry in vacuum. For the case of the vanishing three-form field potential the gravitational field equations can be solved exactly. However, for arbitrary potentials, due to their mathematical complexity, numerical approaches are adopted in studying the behavior of the metric functions and the three-form field. To this effect, the field equations are reformulated in a dimensionless form and are solved numerically by introducing a suitable independent radial coordinate. We detect the formation of a black hole from the presence of a Killing horizon for the time-like Killing vector in the metric tensor components. Several models, corresponding to different functional forms of the three-field potential, namely, the Higgs and exponential type, are considered. In particular, naked singularity solutions are also obtained for the exponential potential case. Finally, the thermodynamic properties of these black hole solutions, such as the horizon temperature, specific heat, entropy and evaporation time due to the Hawking luminosity, are also investigated in detail.
Replacements for Wed, 15 Apr 20
- [73] arXiv:1812.11243 (replaced) [pdf]
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Title: Evaluation of Mother-Daughter Architectures for Asteroid Belt ExplorationComments: 8 pages, 8 Figures, AIAA Scitech Conference 2019Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Earth and Planetary Astrophysics (astro-ph.EP); Space Physics (physics.space-ph)
- [74] arXiv:1901.01095 (replaced) [pdf, other]
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Title: SEAGLE--II: Constraints on feedback models in galaxy formation from massive early type strong lens galaxiesAuthors: Sampath Mukherjee, Leon V. E. Koopmans, R. Benton Metcalf, Crescenzo Tortora, Matthieu Schaller, Joop Schaye, Giorgos Vernardos, Fabio BellagambaComments: re-submitted to MNRAS, bug fixed, conclusions unchanged, updated appendices and references, 23 pages, 10 Figures, 6 TablesSubjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
- [75] arXiv:1901.10311 (replaced) [pdf]
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Title: Reaffirmation of Cosmological Oscillations in the Scale Factor from the Pantheon Compilation of 1048 Type Ia SupernovaeJournal-ref: MNRAS, April 10, 2020Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
- [76] arXiv:1903.10772 (replaced) [pdf, other]
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Title: Modeling the Ly$α$ transit absorption of the hot Jupiter HD 189733bAuthors: P. Odert, N. V. Erkaev, K. G. Kislyakova, H. Lammer, A. V. Mezentsev, V. A. Ivanov, L. Fossati, M. Leitzinger, D. Kubyshkina, M. HolmstroemComments: 22 pages, 19 figures, 4 tables; A&A, acceptedSubjects: Earth and Planetary Astrophysics (astro-ph.EP)
- [77] arXiv:1909.04891 (replaced) [pdf, other]
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Title: Uranus and Neptune: Origin, Evolution and Internal StructureComments: Accepted for publication in Space Science ReviewsSubjects: Earth and Planetary Astrophysics (astro-ph.EP)
- [78] arXiv:1910.10719 (replaced) [pdf, other]
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Title: The Sloan Digital Sky Survey Reverberation Mapping Project: The H$β$ Radius-Luminosity RelationAuthors: Gloria Fonseca Alvarez (1), Jonathan R. Trump (1), Yasaman Homayouni (1), C. J. Grier (2), Yue Shen (3), Keith Horne (4), Jennifer I-Hsiu Li (3), W. N. Brandt (5), Luis C. Ho (6), B. M. Peterson (7), D. P. Schneider (5) ((1) UConn, (2) Arizona, (3) Illinois, (4) St Andrews, (5) Penn State, (6) Kavli Beijing, (7) Ohio State)Comments: 11 pages, 12 figures. Submitted to ApJ. Current version includes revisions after referee reportSubjects: Astrophysics of Galaxies (astro-ph.GA)
- [79] arXiv:1911.11760 (replaced) [pdf, other]
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Title: Early dark energy from massive neutrinos -- a natural resolution of the Hubble tensionComments: Accepted for publication, structural changes but conclusions unchangedSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th)
- [80] arXiv:1912.03640 (replaced) [pdf, ps, other]
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Title: A possible radio signal of annihilating dark matter in the Abell 4038 clusterComments: Submitted to MNRAS LettersSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
- [81] arXiv:1912.11016 (replaced) [pdf, other]
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Title: Multipoles of the relativistic galaxy bispectrumComments: v3 has improved presentation. Version accepted by JCAPSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
- [82] arXiv:1912.12723 (replaced) [pdf, ps, other]
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Title: Stabilizing effect of magnetic helicity on magnetic cavities in the intergalactic mediumComments: 9 pages, 9 figures. Submitted for publicationSubjects: Astrophysics of Galaxies (astro-ph.GA)
- [83] arXiv:2001.00721 (replaced) [pdf, other]
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Title: Phase shift of gravitational waves induced by aberrationComments: 5 pages, 5 figuresSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc)
- [84] arXiv:2001.05487 (replaced) [pdf, other]
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Title: SOFIA/FORCAST Galactic Center Legacy Survey: OverviewAuthors: Matthew J. Hankins, Ryan M. Lau, James T. Radomski, Angela S. Cotera, Mark R. Morris, Elisabeth A. C. Mills, Daniel L. Walker, Ashley T. Barnes, Janet P. Simpson, Terry L. Herter, Steven N. Longmore, John Bally, Mansi M. Kasliwal, Nadeen B. Sabha, Macarena Garcia-MarinComments: 21 pages, 11 figures, Accepted to ApJSubjects: Astrophysics of Galaxies (astro-ph.GA)
- [85] arXiv:2001.05723 (replaced) [pdf, other]
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Title: Gmunu: Toward multigrid based Einstein field equations solver for general-relativistic hydrodynamics simulationsSubjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE)
- [86] arXiv:2001.06037 (replaced) [pdf, other]
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Title: Electromagnetic precursors to gravitational wave events: Numerical simulations of flaring in pre-merger binary neutron star magnetospheresComments: 9 pages, 5 figures, matches version accepted by ApJL, corrected typo in appendixJournal-ref: ApJL 893 L6, 2020Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc)
- [87] arXiv:2001.11444 (replaced) [pdf, other]
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Title: Implications of three-dimensional chemical transport in hot Jupiter atmospheres: results from a consistently coupled chemistry-radiation-hydrodynamics modelAuthors: Benjamin Drummond, Eric Hebrard, Nathan J. Mayne, Olivia Venot, Robert J. Ridgway, Quentin Changeat, Shang-min Tsai, James Manners, Pascal Tremblin, Nathan Luke Abraham, David Sing, Krisztian KoharyComments: Accepted in A&ASubjects: Earth and Planetary Astrophysics (astro-ph.EP)
- [88] arXiv:2002.00572 (replaced) [pdf, other]
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Title: Cosmological parameter measurement and neutral hydrogen 21 cm sky survey with the Square Kilometre ArrayComments: 5 pages, 3 figures; published, as a paper of News & Views, in SCIENCE CHINA Physics, Mechanics & AstronomyJournal-ref: Sci. China-Phys. Mech. Astron. 63, 270431 (2020)Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph)
- [89] arXiv:2002.08962 (replaced) [pdf, other]
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Title: Gravitational microlensing by dark matter in extended structuresComments: 11 pages revtex4, 5 figures, 1 table; v2: Fig 1 redrawn, conclusions unchanged, references added, matches PRD versionJournal-ref: Phys. Rev. D 101, 083013 (2020)Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph)
- [90] arXiv:2002.10287 (replaced) [pdf, other]
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Title: Inequalities faced by women in access to permanent positions in astronomy in FranceJournal-ref: Nature astronomy, 4, 296-298, 2020Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
- [91] arXiv:2002.11460 (replaced) [pdf, other]
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Title: The Fourth Fermi-GBM Gamma-Ray Burst Catalog: A Decade of DataAuthors: A. von Kienlin, C. A. Meegan, W. S. Paciesas, P. N. Bhat, E. Bissaldi, M. S. Briggs, E. Burns, W. H. Cleveland, M. H. Gibby, M. M. Giles, A. Goldstein, R. Hamburg, C. M. Hui, D. Kocevski, B. Mailyan, C. Malacaria, S. Poolakkil, R. D. Preece, O. J. Roberts, P. Veres, C. A. Wilson-HodgeComments: 273 pages, 10 figures, 8 tables. arXiv admin note: text overlap with arXiv:1603.07612Journal-ref: ApJ 893, 46 (2020)Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
- [92] arXiv:2003.01222 (replaced) [pdf, other]
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Title: The Koala: A Fast Blue Optical Transient with Luminous Radio Emission from a Starburst Dwarf Galaxy at $z=0.27$Authors: Anna Y. Q. Ho (1), D. A. Perley (2) S. R. Kulkarni (1), D. Z. J. Dong (1), K. De (1), P. Chandra (3), I. Andreoni (1), E. C. Bellm (4), K. B. Burdge (1), M. Coughlin (5), R. Dekany (6), M. Feeney (6), D. D. Frederiks (7), C. Fremling (1), V. Z. Golkhou (4,8), M. Graham (1), D. Hale (6), G. Helou (9), A. Horesh (10), R. R. Laher (9), F. Masci (9), A. A. Miller (11,12), M. Porter (6), A. Ridnaia (7), B. Rusholme (9), D. L. Shupe (9), M. T. Soumagnac (13,14), D. S. Svinkin (7) ((1) Caltech, (2) LJMU, (3) NCRA, (4) DIRAC Institute, (5) U. Minnesota, (6) COO, (7) Ioffe Institute, (8) eScience Institute, (9) IPAC, (10) Racah Institute, (11) CIERA, (12) Adler, (13) LBNL, (14) Weizmann)Comments: 27 pages, 11 figures. Resubmitted to ApJ on 13 April following comments by referee. Comments welcome!Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
- [93] arXiv:2003.07707 (replaced) [pdf, other]
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Title: Mitigating flicker noise in high-precision photometry. I -- Characterization of the noise structure, impact on the inferred transit parameters, and predictions for CHEOPS observationsComments: 20 pages, 24 figures, accepted for publication in Astronomy & AstrophysicsSubjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
- [94] arXiv:2004.02963 (replaced) [pdf, other]
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Title: Multipole alignment in the large-scale distribution of spin direction of spiral galaxiesAuthors: Lior ShamirComments: To be submitted. Comments welcomeSubjects: Astrophysics of Galaxies (astro-ph.GA)
- [95] arXiv:2004.04991 (replaced) [pdf, other]
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Title: Liverpool-Maidanak monitoring of the Einstein Cross in 2006$-$2019. I. Light curves in the $gVrRI$ optical bands and microlensing signaturesAuthors: L. J. Goicoechea, B. P. Artamonov, V. N. Shalyapin, A. V. Sergeyev, O. A. Burkhonov, T. A. Akhunov, I. M. Asfandiyarov, V. V. Bruevich, S. A. Ehgamberdiev, E. V. Shimanovskaya, A. P. ZheleznyakComments: Accepted to A&A; 10 pages, 10 long tables (Tables 4-8 and 10-14) are available at the CDS; correction of affiliationSubjects: Astrophysics of Galaxies (astro-ph.GA)
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