Astrophysics
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New submissions for Tue, 19 Nov 19
- [1] arXiv:1911.06823 [pdf, other]
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Title: Effectively using unsupervised machine learning in next generation astronomical surveysComments: Comments are welcome! The portal is available at this https URLSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Astrophysics of Galaxies (astro-ph.GA)
In recent years many works have shown that unsupervised Machine Learning (ML) can help detect unusual objects and uncover trends in large astronomical datasets, but a few challenges remain. We show here, for example, that different methods, or even small variations of the same method, can produce significantly different outcomes. While intuitively somewhat surprising, this can naturally occur when applying unsupervised ML to highly dimensional data, where there can be many reasonable yet different answers to the same question. In such a case the outcome of any single unsupervised ML method should be considered a sample from a conceivably wide range of possibilities. We therefore suggest an approach that eschews finding an optimal outcome, instead facilitating the production and examination of many valid ones. This can be achieved by incorporating unsupervised ML into data visualisation portals. We present here such a portal that we are developing, applied to the sample of SDSS spectra of galaxies. The main feature of the portal is interactive 2D maps of the data. Different maps are constructed by applying dimensionality reduction to different subspaces of the data, so that each map contains different information that in turn gives a different perspective on the data. The interactive maps are intuitive to use, and we demonstrate how peculiar objects and trends can be detected by means of a few button clicks. We believe that including tools in this spirit in next generation astronomical surveys will be important for making unexpected discoveries, either by professional astronomers or by citizen scientists, and will generally enable the benefits of visual inspection even when dealing with very complex and extensive datasets. Our portal is available online at galaxyportal.space.
- [2] arXiv:1911.06825 [pdf, other]
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Title: Star-gas misalignment in galaxies: I. The properties of galaxies from the Horizon-AGN simulation and comparisons to SAMIAuthors: Donghyeon J. Khim, Sukyoung K. Yi, Yohan Dubois, Julia J. Bryant, Christophe Pichon, Scott M. Croom, Joss Bland-Hawthorn, Sarah Brough, Hoseung Choi, Julien Devriendt, Brent Groves, Matt S. Owers, Samuel N. Richards, Jesse van de Sande, Sarah M. SweetComments: 18 pages with 11 figures. Submitted to ApJ. Comments welcomeSubjects: Astrophysics of Galaxies (astro-ph.GA)
Recent integral field spectroscopy observations have found that about 11\% of galaxies show star-gas misalignment. The misalignment possibly results from external effects such as gas accretion, interaction with other objects, and other environmental effects, hence providing clues to these effects. We explore the properties of misaligned galaxies using Horizon-AGN, a large-volume cosmological simulation, and compare the result with the result of the Sydney-AAO Multi-object integral field spectrograph (SAMI) Galaxy Survey. Horizon-AGN can match the overall misalignment fraction and reproduces the distribution of misalignment angles found by observations surprisingly closely. The misalignment fraction is found to be highly correlated with galaxy morphology both in observations and in the simulation: early-type galaxies are substantially more frequently misaligned than late-type galaxies. The gas fraction is another important factor associated with misalignment in the sense that misalignment increases with decreasing gas fraction. However, there is a significant discrepancy between the SAMI and Horizon-AGN data in the misalignment fraction for the galaxies in dense (cluster) environments. We discuss possible origins of misalignment and disagreement.
- [3] arXiv:1911.06826 [pdf, other]
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Title: Chemo-dynamics of barred galaxies in the Auriga simulations: The in-situ formation of the Milky Way bulgeAuthors: F. Fragkoudi, R. J. J. Grand, R. Pakmor, G. Blázquez-Calero, I. Gargiulo, F. Gomez, F. Marinacci, A. Monachesi, M. K. Ness, I. Perez, P. Tissera, S. D. M. WhiteComments: Submitted to MNRASSubjects: Astrophysics of Galaxies (astro-ph.GA)
We explore a sample of barred galaxies in the Auriga magneto-hydrodynamical cosmological zoom-in simulations that form boxy/peanut (b/p) bulges. The morphology of bars and b/p's vary for different mono-abundance populations, according to their kinematic properties, which are in turn set by the galaxy's assembly history. We find that the Auriga galaxies which best reproduce the chemo-kinematic properties of the Milky Way bulge have a negligible fraction of ex-situ stars in the b/p region ($<1\%$), with flattened, thick disc-like metal-poor stellar populations, and with their last major merger occurring at $t_{\rm lookback}>12\,\rm Gyrs$. This imposes an upper limit on the stellar mass ratio of subsequent mergers, which we find is broadly consistent with the recently proposed Gaia Sausage/Enceladus merger. The average fraction of ex-situ stars in the central regions of Auriga galaxies that form b/p's is $3\%$ -- significantly lower than in those which do not form bars or b/p's. While these central regions contain the oldest populations, they also have stars younger than 5Gyrs ($>30\%$) and exhibit X-shaped age and abundance distributions. Furthermore, we present a novel method, based on kinematics, for detecting asymmetric (buckling) b/p's in face-on galaxies. Examining the inner discs of galaxies in our sample, we find that in some cases a metal-rich, star-forming inner ring forms, which surrounds the bar. Further out, bar-induced resonances form ridges in the $V_{\phi}-r$ plane -- the longest of which is due to the Outer Lindblad Resonance -- which are younger and more metal-rich than the surrounding phase-space. Our results suggest an in-situ origin for the Milky Way bulge and highlight the significant effect the bar can have on the surrounding disc.
- [4] arXiv:1911.06827 [pdf, other]
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Title: GFiRe: a Gauge Field integrator for ReheatingComments: 35 pages, 13 figuresSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Lattice (hep-lat); High Energy Physics - Phenomenology (hep-ph)
We present a new numerical algorithm and code, ${\sf GFiRe}$, for solving the non-linear evolution of Abelian gauge fields coupled to complex scalar fields in homogeneous and isotropic spacetimes. We adopt a hybrid approach to solving the system: the spatial derivatives are discretized using standard Lattice Gauge Field Theory techniques, whereas the time evolution of the fields and scalefactor is implemented with explicit, composite, symplectic integrators. An important property of our compound algorithm is that the discretized Gauss constraint is respected exactly, regardless of the order of the symplectic integrator. This remains true even when the background expansion is computed ``self-consistently''; that is, when the expansion history is computed using spatial averaged components of the energy momentum tensor in the simulation volume. Hence, our code can also be used in cases where the fields dominate the energy density of the universe, for example, during reheating after inflation.
We test the algorithm in scenarios of reheating where the inflaton is a complex scalar field with a potential $\propto(2|\varphi|^2-v^2)^2$ and is coupled to an Abelian gauge field. Tracing the evolution of the system through complex dynamics (including resonant excitation of fields, backreaction, formation of solitons, and changes in the equation of state) in a self-consistently expanding universe, we find the energy conservation violation ($<10^{-4}$) to be very stable and the Gauss constraint violation ($<10^{-6}$) to be dominated by differencing noise. - [5] arXiv:1911.06828 [pdf, other]
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Title: Self similar Shocks in Atmospheric Mass Loss due to Planetary CollisionsComments: Submitted to Atmosphere special issue "Shock Wave Dynamics and Its Effects on Planetary Atmospheres"Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
We present a mathematical model for the propagation of the shock waves that occur during planetary collisions. Such collisions are thought to occur during the formation of terrestrial planets, and they have the potential to erode the planet's atmosphere. We show that under certain assumptions, this evolution of the shock wave can be determined using the method of self similar solutions. This self similar solution is of type II, which means that it only applies to a finite region behind the shock front. This region is bounded by the shock front and the sonic point. Energy and matter continuously flow through the sonic point, so that energy in the self similar region is not conserved, as is the case for type I solutions. Instead, the evolution of the shock wave is determined by boundary conditions at the shock front and at the sonic point. We show how the evolution can be determined for different equations of state, allowing these results to be readily used to calculate the atmospheric mass loss from planetary cores made of different materials.
- [6] arXiv:1911.06829 [pdf, other]
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Title: Exploring the High-Mass End of the Stellar Mass Function of Star Forming Galaxies at Cosmic NoonAuthors: Sydney Sherman, Shardha Jogee, Jonathan Florez, Matthew L. Stevans, Lalitwadee Kawinwanichakij, Isak Wold, Steven L. Finkelstein, Casey Papovich, Viviana Acquaviva, Robin Ciardullo, Carly Gronwall, Zacharias EscalanteComments: 19 pages, 10 figures, Accepted for publication in MNRASSubjects: Astrophysics of Galaxies (astro-ph.GA)
We present the high-mass end of the galaxy stellar mass function using the largest sample to date (5,352) of star-forming galaxies with $M_{\star} > 10^{11} M_{\odot}$ at cosmic noon, $1.5 < z < 3.5$. This sample is uniformly selected across 17.2 deg$^2$ ($\sim$0.44 Gpc$^3$ comoving volume from $1.5 < z < 3.5$), mitigating the effects of cosmic variance and encompassing a wide range of environments. This area, a factor of 10 larger than previous studies, provides robust statistics at the high-mass end. Using multi-wavelength data in the Spitzer/HETDEX Exploratory Large Area (SHELA) footprint we find that the SHELA footprint star-forming galaxy stellar mass function is steeply declining at the high-mass end probing values as high as $\sim$$10^{-4}$ Mpc$^3$/dex and as low as $\sim$5$\times$$10^{-8}$ Mpc$^3$/dex across a stellar mass range of log($M_\star$/$M_\odot$) $\sim$ 11 - 12. We compare our empirical star-forming galaxy stellar mass function at the high mass end to three types of numerical models: hydrodynamical models from IllustrisTNG, abundance matching from the UniverseMachine, and three different semi-analytic models (SAMs; SAG, SAGE, GALACTICUS). At redshifts $1.5 < z < 3.5$ we find that results from IllustrisTNG and abundance matching models agree within a factor of $\sim$2 to 10, however the three SAMs strongly underestimate (up to a factor of 1,000) the number density of massive galaxies. We discuss the implications of these results for our understanding of galaxy evolution.
- [7] arXiv:1911.06830 [pdf, other]
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Title: Radiative kinetic simulations of steady-state relativistic plasmoid magnetic reconnectionComments: 17 pages, 15 images, submitted to MNRASSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
We present the results of 2D particle-in-cell (PIC) simulations of relativistic magnetic reconnection (RMR) in electron-positron plasma, including the dynamical influence of the synchrotron radiation process, and integrating the observable emission signatures. The simulations are initiated with a single Harris current layer with a central gap that triggers the RMR process. We achieve a steady-state reconnection with unrestricted outflows by means of open boundary conditions. The radiative cooling efficiency is regulated by the choice of initial plasma temperature Theta. We explore different values of Theta and of the background magnetisation sigma_0. Throughout the simulations, plasmoids are generated in the central region of the layer, and they evolve at different rates, achieving a wide range of sizes. The gaps between plasmoids are filled by smooth relativistic outflows called minijets, whose contribution to the observed radiation is very limited due to their low particle densities. Small-sized plasmoids are rapidly accelerated, however, they have lower contributions to the observed emission, despite stronger relativistic beaming. Large-sized plasmoids are slow, but produce most of the observed synchrotron emission, with major part of their radiation produced within the central cores, the density of which is enhanced by radiative cooling. Synchrotron lightcurves show rapid bright flares that can be identified as originating from tail-on mergers between small/fast plasmoids and large/slow targets.
- [8] arXiv:1911.06839 [pdf, ps, other]
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Title: Estimation of Key Sunquake Parameters through Hydrodynamic Modeling and Cross-Correlation AnalysisSubjects: Solar and Stellar Astrophysics (astro-ph.SR)
Sunquakes are one of the more distinct secondary phenomena related to solar flares, where energy deposition in the lower layers of the Sun's atmosphere excites acoustic waves easily visible in HMI dopplergrams. We explore two possible sources of sunquakes in the context of the electron beam hypothesis, as an instantaneous transfer of momentum and as a gradual applied force. We model the sunquake excitation and compare with five observed sunquake events using a cross-correlation analysis. We find that at least half the events studied are consistent with the electron beam hypothesis and estimate the energy required to excite the sunquakes to be within the range determined by previous studies.
- [9] arXiv:1911.06852 [pdf]
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Title: When is chemical disequilibrium in Earth-like planetary atmospheres a biosignature versus an anti-biosignature? Disequilibria from dead to living worldsComments: Submitted this draft to Astrophysical Journal on 11/14/19Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Chemical disequilibrium in exoplanetary atmospheres (detectable with remote spectroscopy) can indicate life. The modern Earth's atmosphere-ocean system has a much larger chemical disequilibrium than other solar system planets with atmospheres because of oxygenic photosynthesis. However, no analysis exists comparing disequilibrium on lifeless, prebiotic planets to disequilibrium on worlds with primitive chemotrophic biospheres that live off chemicals and not light. Here, we use a photochemical-microbial ecosystem model to calculate the atmosphere-ocean disequilibria of Earth with no life and with a chemotrophic biosphere. We show that the prebiotic Earth likely had a relatively large atmosphere-ocean disequilibrium due to the coexistence of water and volcanic H2, CO2, and CO. Subsequent chemotrophic life likely destroyed nearly all of the prebiotic disequilibrium through its metabolism, leaving a likely smaller disequilibrium between N2, CO2, CH4, and liquid water. So, disequilibrium fell with the rise of chemotrophic life then later rose with atmospheric oxygenation due to oxygenic photosynthesis. We conclude that big prebiotic disequilibrium between H2 and CO2 or CO and water is an anti-biosignature because these easily metabolized species can be eaten due to redox reactions with low activation energy barriers. However, large chemical disequilibrium can also be a biosignature when the disequilibrium arises from a chemical mixture with biologically insurmountable activation energy barriers, and clearly identifiable biogenic gases. The modern disequilibrium between O2, N2, and liquid water along with minor CH4 is such a case. Thus, the interpretation of disequilibrium requires context. With context, disequilibrium can be used to infer dead or living worlds.
- [10] arXiv:1911.06860 [pdf, other]
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Title: Autonomous Gaussian decomposition of the Galactic Ring Survey. I. Global statistics and properties of the 13CO emission dataComments: Accepted for publication in A&A. 26 pages, 25 figures (main text: 16 pages, 16 figures; Appendix: 10 pages, 9 figures). The PDF contains multi-layer figures that can be displayed with Adobe Acrobat. Table 1 with the full decomposition results will be made publicly available soon; earlier access to the data is possible upon request from the corresponding author (M. Riener). Comments are welcomeSubjects: Astrophysics of Galaxies (astro-ph.GA)
The analysis of large molecular line surveys of the Galactic plane is essential for our understanding of the gas kinematics on Galactic scales, in particular its link with the formation and evolution of dense structures in the interstellar medium. An approximation of the emission peaks with Gaussian functions allows for an efficient and straightforward extraction of useful physical information contained in the shape and Doppler-shifted frequency of the emission lines contained in these enormous data sets. In this work we present an overview and first results of a Gaussian decomposition of the entire Galactic Ring Survey (GRS) 13CO (1-0) data that consists of about 2.3 million spectra. We performed the decomposition with the fully automated GaussPy+ algorithm and fitted about 4.6 million Gaussian components to the GRS spectra. We discuss the statistics of the fit components and relations between the fitted intensities, velocity centroids, and velocity dispersions. We find that the magnitude of the velocity dispersion values increase toward the inner Galaxy and around the Galactic midplane, which we speculate is partly due to the influence of the Galactic bar and regions with higher non-thermal motions located in the midplane, respectively. We also use our decomposition results to infer global properties of the gas emission and find that the number of fit components used per spectrum is indicative for the amount of structure along the line of sight. We find that the emission lines from regions located on the far side of the Galaxy show increased velocity dispersion values, likely due to beam averaging effects. We demonstrate how this trend has the potential to aid in characterising Galactic structure by disentangling emission that is belonging to the nearby Aquila Rift molecular cloud from emission that is more likely associated with the Perseus and Outer spiral arms.
- [11] arXiv:1911.06864 [pdf, other]
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Title: Observation of Acceleration of HI Clouds Within the Fermi BubblesComments: Accepted for publication in the Astrophysical JournalSubjects: Astrophysics of Galaxies (astro-ph.GA)
The ~200 HI clouds observed to be entrained in the Fermi Bubble wind show a trend of increasing maximum |VLSR| with Galactic latitude. We analyze previous observations and present new data from the Green Bank Telescope that rule out systematic effects as the source of this phenomenon. Instead, it is likely evidence for acceleration of the clouds. The data suggest that clouds in the lower 2 kpc of the Fermi Bubbles, within the Bubble boundaries established from X-ray studies, have an outflow velocity that rises from ~150 - 200 km/s close to the Galactic Center and reaches ~330 km/s at a distance of 2.5 - 3.5 kpc. These parameters are also consistent with the kinematics of UV absorption lines from highly ionized species observed against two targets behind the Fermi Bubbles at $b = -6.6^{\circ}$, and $b = +11.2^{\circ}$. The implied neutral cloud lifetime is 4 - 10 Myr.
- [12] arXiv:1911.06865 [pdf, other]
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Title: The great impostors: Extremely compact, merging binary neutron stars in the mass gap posing as binary black holesComments: 8 pages, 9 figuresSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc)
Can one distinguish a binary black hole undergoing a merger from a binary neutron star if the individual compact companions have masses that fall inside the so-called mass gap of $3-5\ M_\odot$? For neutron stars, achieving such masses typically requires extreme compactness and in this work we present initial data and evolutions of binary neutron stars initially in quasiequilibrium circular orbits having a compactness $C=0.336$. These are the most compact, nonvacuum, quasiequilibrium binary objects that have been constructed and evolved to date, including boson stars. The compactness achieved is only slightly smaller than the maximum possible imposed by causality, $C_{\rm max}=0.355$, which requires the sound speed to be less than the speed of light. By comparing the emitted gravitational waveforms from the late inspiral to merger and post-merger phases between such a binary neutron star \textit{vs.} a binary black hole of the same total mass we identify concrete measurements that serve to distinguish them. With that level of compactness, the binary neutron stars exhibit no tidal disruption up until merger, whereupon a prompt collapse is initiated even before a common core forms. Within the accuracy of our simulations the black hole remnants from both binaries exhibit ringdown radiation that is not distinguihable from a perturbed Kerr spacetime. However, their inspiral leads to phase differences of the order of $\sim 4$ rads over an $\sim 81$ km separation (1.7 orbits) while typical neutron stars exhibit phase differences of $\geq 20$ rads. Although a difference of $4$ rads can be measured by current gravitational wave laser interferometers (e.g. aLIGO/Virgo), uncertainties in the orbital parameters will likely prevent distinguishing such compact, massive neutron stars from black holes.
- [13] arXiv:1911.06881 [pdf, other]
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Title: Spectral characteristic of mid-term quasi-periodicities in sunspots dataComments: accepted in MNRASSubjects: Solar and Stellar Astrophysics (astro-ph.SR)
Numerous analyses suggest the existence of various quasi-periodicities in solar activity. The power spectrum of solar activity recorded in sunspot data is dominated by the $\sim$11-year quasi-periodicity, known as the Schwabe cycle. In the mid-term range (1 month -- 11 years) a pronounced variability known as a quasi-biennial oscillation (QBO) is widely discussed. In the shorter time scale a pronounced peak, corresponding to the synodic solar rotation period ($\sim$ 27 days) is observed. Here we revisited the mid-term solar variability in terms of statistical dynamic of fully turbulent systems, where solid arguments are required to accept an isolated dominant frequency in a continuous (smooth) spectrum. For that, we first undertook an unbiased analysis of the standard solar data, sunspot numbers and the F10.7 solar radioflux index, by applying a wavelet tool, which allows one to perform a frequency-time analysis of the signal. Considering the spectral dynamics of solar activity cycle by cycle, we showed that no single periodicity can be separated, in a statistically significant manner, in the specified range of periods. We examine whether a model of solar dynamo can reproduce the mid-term oscillation pattern observed in solar data. We found that a realistically observed spectrum can be explained if small spatial (but not temporal) scales are effectively smoothed. This result is important because solar activity is a it global feature, although monitored via small-scale tracers like sunspots.
- [14] arXiv:1911.06925 [pdf, other]
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Title: Spatially-Resolved Spectroscopic Properties of Low-Redshift Star-Forming GalaxiesAuthors: Sebastian F. SanchezComments: 53 pages, 20 Figues, first draft of a review to be published at ARAA, largely modified in the final version Additiona material: this http URLSubjects: Astrophysics of Galaxies (astro-ph.GA)
I review here the spatially-resolved spectroscopic properties of low-redshift star-forming galaxies (and their retired counter-parts), using results from the most recent Integral Field Spectroscopy galaxy surveys. First, I briefly summarise the global spectroscopic properties of these galaxies, discussing the main ionization processes, and the global relations described between the star-formation rates, oxygen abundances, and average properties of their stellar populations (age and metallicity) with the stellar mass. Second, I present the local distribution of the ionizing processes, down to kiloparsec scales, and I show how the global scaling relations found between integrated parameters (like the star-formation main sequence, mass-metallicity relation and Schmidt-Kennicutt law) present local/resolved counter-parts, with the global ones being just integrated/average versions of the local ones. I discuss the local/resolved star-formation and chemical enrichment histories and their implication on the inside-out growth of galaxies. Third, I present the radial distributions of the surface densities of the properties explored globally, and how they depend on the integrated galaxy properties. Finally, I summarise all these results and discuss what we have learned from them regarding the evolution of galaxies.
- [15] arXiv:1911.06941 [pdf, ps, other]
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Title: Exploring the convective core of the hybrid $δ$ Scuti-$γ$ Doradus star CoRoT 100866999 with asteroseismologyComments: 7 figures and 6 tables. accepted by ApJSubjects: Solar and Stellar Astrophysics (astro-ph.SR)
We computed a grid of theoretical models to fit the $\delta$ Scuti frequencies of CoRoT 100866999 detected earlier from the CoRoT timeserials. The pulsating primary star is determined to be a main sequence star with a rotation period of $4.1^{+0.6}_{-0.5}$ days, rotating slower than the orbital motion. The fundamental parameters of the primary star are determined to be $M$ = $1.71^{+0.13}_{-0.04}$ $M_{\odot}$, $Z=0.012^{+0.004}_{-0.000}$, $f_{\rm ov}$ = $0.02^{+0.00}_{-0.02}$, $T_{\rm eff}$ = $8024^{+249}_{-297}$ K, $L$ = $11.898^{+2.156}_{-1.847}$ $L_{\odot}$, $\log g$ = $4.166^{+0.013}_{-0.002}$, $R$ = $1.787^{+0.040}_{-0.016}$ $R_{\odot}$, and $X_{\rm c}$ = 0.488$^{+0.011}_{-0.020}$, matching well those obtained from the eclipsing light curve analysis. Based on the model fittings, $p_1$ and $p_5$ are suggested to be two dipole modes, and $p_3$, $p_4$, $p_6$, and $p_7$ to be four quadrupole modes. In particular, $p_4$ and $p_7$ are identified as two components of one quintuplet. Based on the best-fitting model, we find that $p_1$ is a g mode and the other nonradial modes have pronounced mixed characters, which give strong constraints on the convective core. Finally, the relative size of the convective core of CoRoT 100866999 is determined to $R_{\rm conv}/R$ = $0.0931^{+0.0003}_{-0.0013}$.
- [16] arXiv:1911.06942 [pdf, ps, other]
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Title: Upward Overshooting in Turbulent Compressible Convection. I.Effects of the relative stability parameter, the Prandtl number, and the Péclet numberAuthors: Tao CaiComments: Accepted for publication in the Astrophysical JournalSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Fluid Dynamics (physics.flu-dyn)
In this paper, we investigate the upward overshooting by three-dimensional numerical simulations. We find that the above convectively stable zone can be partitioned into three layers: the thermal adjustment layer (mixing both entropy and material), the turbulent dissipation layer (mixing material but not entropy), and the thermal dissipation layer (mixing neither entropy nor material). The turbulent dissipation layer is separated from the thermal adjustment layer and the thermal dissipation layer by the first and second zero points of the vertical velocity correlation. The simulation results are in good agreement with the prediction of the one-dimensional turbulent Reynolds stress model. First, the layer structure is similar. Second, the upper boundary of the thermal adjustment layer is close to the peak of the magnitude of the temperature perturbation. Third, the P\'eclet number at the upper boundary of the turbulent dissipation layer is close to 1. In addition, we have studied the scalings of the overshooting distance on the relative stability parameter $S$, the Prandtl number $\rm Pr$, and the P\'eclet number $\rm Pe$. The scaling on $S$ is not unique. The trend is that the overshooting distance decreases with $S$. Fitting on $\rm Pr$ shows that the overshooting distance increases with $\rm Pr$. Fitting on $\rm Pe$ shows that the overshooting distance decreases with $\rm Pe$. Finally, we calculate the ratio of the thickness of the turbulent dissipation layer to that of the thermal adjustment layer. The ratio remains almost constant, with an approximate value of 2.4.
- [17] arXiv:1911.06945 [pdf, ps, other]
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Title: On the rapid orbital expansion in the compact low-mass X-ray binary 2A 1822$-$371Comments: 14 pages, 10 figures, accepted for publication in ApJSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
The neutron star low-mass X-ray binary 2A 1822$-$371 has an orbital period of 5.57 hr. Mass transfer in such short-period binaries is thought to be driven by magnetic braking with orbital shrinking. However, 2A 1822$-$371 shows a very rapid orbital expansion, implying that mass transfer occurs rapidly in this system. The accretion rate of the neutron star is observationally estimated to be higher than the Eddington limit, which is also hard to be explained by the standard magnetic braking mechanism. In this work, we construct a model to account for the peculiar properties of 2A 1822$-$371. We assume that the donor star possesses a relatively strong magnetic field, which is coupled with the stellar winds excited by the X-ray radiation from the neutron star. This would generate efficient angular momentum loss, leading to a high mass transfer rate and hence orbital expansion. We provide possible evolutionary tracks of 2A 1822$-$371 and study how the input parameters affect the results. The observational implications of the irradiation-driven mass loss are also briefly discussed in the context of evolution of low-mass X-ray binaries and millisecond pulsars.
- [18] arXiv:1911.06952 [pdf, other]
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Title: The landscape of Saturn's internal magnetic field from the Cassini Grand FinaleAuthors: Hao Cao, Michele K. Dougherty, Gregory J. Hunt, Gabrielle Provan, Stanley W.H. Cowley, Emma J. Bunce, David J. StevensonComments: Accepted for publication in IcarusSubjects: Earth and Planetary Astrophysics (astro-ph.EP)
The Cassini mission entered the Grand Finale phase in April 2017 and executed 22.5 highly inclined, close-in orbits around Saturn before diving into the planet on September 15th 2017. Here we present our analysis of the Cassini Grand Finale magnetometer (MAG) dataset, focusing on Saturn's internal magnetic field. These measurements demonstrate that Saturn's internal magnetic field is exceptionally axisymmetric, with a dipole tilt less than 0.007 degrees (25.2 arcsecs). Saturn's magnetic equator was directly measured to be shifted northward by ~ 0.0468 +/- 0.00043 (1-sigma) $R_S$, 2820 +/- 26 km, at cylindrical radial distances between 1.034 and 1.069 $R_S$ from the spin-axis. Although almost perfectly axisymmetric, Saturn's internal magnetic field exhibits features on many characteristic length scales in the latitudinal direction. Examining Br at the a=0.75 $R_S$, c=0.6993 $R_S$ isobaric surface, the degrees 4 to 11 contributions correspond to latitudinally banded magnetic perturbations with characteristic width similar to that of the off-equatorial zonal jets observed in the atmosphere of Saturn. Saturn's internal magnetic field beyond 60 degrees latitude, in particular the small-scale features, are less well constrained by the available measurements, mainly due to incomplete spatial coverage in the polar region. A stably stratified layer thicker than 2500 km likely exists above Saturn's deep dynamo to filter out the non-axisymmetric internal magnetic field. A heat transport mechanism other than pure conduction, e.g. double diffusive convection, must be operating within this layer to be compatible with Saturn's observed luminosity. The latitudinally banded magnetic perturbations likely arise from a shallow secondary dynamo action with latitudinally banded differential rotation in the semi-conducting layer.
- [19] arXiv:1911.07002 [pdf, other]
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Title: A New Channel of Bulge Formation via The Destruction of Short BarsComments: 16 pages, 11 figures, accepted for publication in ApJSubjects: Astrophysics of Galaxies (astro-ph.GA)
Short (inner) bars of sub-kiloparsec radius have been hypothesized to be an important mechanism for driving gas inflows to small scales, thus feeding central black holes. Recent numerical simulations have shown that the growth of central black holes in galaxies can destroy short bars, when the black hole reaches a mass of $\sim 0.1\%$ of the total stellar mass of the galaxy. We study $N$-body simulations of galaxies with single and double bars to track the long-term evolution of the central stellar mass distribution. We find that the destruction of the short bar contributes significantly to the growth of the bulge. The final bulge mass is roughly equal to the sum of the masses of the initial pseudo bulge and short bar. The initially boxy/peanut-shaped bulge of S\'ersic index $n\lesssim1$ is transformed into a more massive, compact structure that bears many similarities to a classical bulge, in terms of its morphology ($n \approx 2$), kinematics (dispersion-dominated, isotropic), and location on standard scaling relations (Kormendy relation, mass-size relation, and correlations between black hole mass and bulge stellar mass and velocity dispersion). Our proposed channel for forming classical bulges relies solely on the destruction of short bars without any reliance on mergers. We suggest that some of the less massive, less compact classical bulges were formed in this manner.
- [20] arXiv:1911.07032 [pdf, ps, other]
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Title: Two New Rapidly-Rotating ON Stars Found With LAMOSTComments: 8 pages, 4 figures, 2 tablesSubjects: Solar and Stellar Astrophysics (astro-ph.SR)
The ON stars are a rare subtype of O stars, of uncertain origin. We report two new, rapidly-rotating ON stars found in data acquired with the Large Sky Area Multi-Object Fiber Spectroscopic Telescope, LAMOST. LS I +61 28 is an ON8.5 Vn dwarf with a projected equatorial rotational velocity of $v_{\textrm e}\sin{i} \simeq 298$ km$\;$s$^{-1}$, while HDE 236672 is an ON9 IVn subgiant with $v_{\textrm e}\sin{i} \simeq 253$ km$\;$s$^{-1}$ The former is the first rapidly-rotating ON dwarf to be found, and the latter is only the third ON subgiant. The luminosity classes of non-supergiant ON stars appear to be influenced by the axial inclination angle $i$: the rapidly-rotating giants are close to equator-on, while ON dwarfs with lower $v_{\textrm e}\sin{i}$ values are viewed more nearly pole-on. Combining parallaxes and proper motions from Gaia DR2 with radial-velocity measurements, we investigate the kinematics of non-supergiant ON stars, and infer that the dynamics, rapid rotation, and surface-nitrogen characteristics may all be consequences of binary interaction.
- [21] arXiv:1911.07054 [pdf, ps, other]
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Title: Periodic transit timing variations and refined system parameters of the exoplanet XO-6bAuthors: Zoltán Garai, Theodor Pribulla, Richard Komžík, Emil Kundra, Ľubomír Hambálek, Gyula M. SzabóComments: Accepted for publication in MNRASSubjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
Only a few exoplanets are known to orbit around fast rotating stars. One of them is XO-6b, which orbits an F5V-type star. Shortly after the discovery, we started multicolor photometric and radial-velocity follow-up observations of XO-6b, using the telescopes of Astronomical Institute of the Slovak Academy of Sciences. Our main scientific goals were to better characterize the planetary system and to search for transit timing variations. We refined several planetary and orbital parameters. Based on our measurements, the planet XO-6b seems to be about 10% larger, which is, however, only about $2\sigma$ difference, but its orbit inclination angle, with respect to the plane of the sky, seems to be significantly smaller, than it was determined originally by the discoverers. In this case we found about $9.5\sigma$ difference. Moreover, we observed periodic transit timing variations of XO-6b with a semi-amplitude of about 14 min and with a period of about 450 days. There are two plausible explanations of such transit timing variations: (1) a third object in the system XO-6 causing light-time effect, or (2) resonant perturbations between the transiting planet XO-6b and another unknown low-mass planet in this system. From the O-C diagram we derived that the assumed third object in the system should have a stellar mass, therefore significant variations are expected in the radial-velocity measurements of XO-6. Since this is not the case, and since all attempts to fit radial velocities and O-C data simultaneously failed to provide a consistent solution, more realistic is the second explanation.
- [22] arXiv:1911.07075 [pdf, other]
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Title: Clusters and mirages: cataloguing stellar aggregates in the Milky WayComments: Accepted A&A, 24 pagesSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)
Many open clusters listed in modern catalogues were initially reported by visual astronomers as apparent overdensities of bright stars. As observational techniques and analysis methods continue to improve, some of them have been shown to be chance alignments of stars and not true clusters. Recent publications have provided membership lists for over a thousand clusters, however, many nearby objects listed in the literature have so far evaded detection. We aim to update the Gaia DR2 cluster census by performing membership determinations for known clusters that had been missed by previous studies and for recently-discovered clusters. We investigate a sub-set of non-detected clusters that, according to their literature parameters, should be easily visible in Gaia. Confirming or disproving the existence of old, inner-disc, high-altitude clusters is especially important as their survival or disruption is linked to the dynamical processes that drive the evolution of the Milky Way. We employed the Gaia DR2 catalogue and a membership assignment procedure, as well as visual inspections of spatial, proper motion, and parallax distributions. We used membership lists provided by other authors when available. We derived membership lists for 150 objects, including ten that were already known prior to Gaia. We compiled a final list of members for 1481 clusters. Among the objects that we are still unable to identify with the Gaia data, we argue that many (mostly putatively old, relatively nearby, high-altitude objects) are not true clusters. At present, the only confirmed cluster located further than 500pc away from the Galactic plane within the Solar circle is NGC 6791. It is likely that the objects discussed in this study only represent a fraction of the non-physical groupings erroneously listed in the catalogues as genuine open clusters and that those lists need further cleaning.
- [23] arXiv:1911.07120 [pdf, other]
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Title: Twisted debris: how differential secular perturbations shape debris disksComments: 12 pages, 7 figuresJournal-ref: A&A Volume 631, November 2019, A141Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Resolved images suggest that asymmetric structures are a common feature of cold debris disks. While planets close to these disks are rarely detected, their hidden presence and gravitational perturbations provide plausible explanations for some of these features. To put constraints on the properties of yet undetected planetary companions, we aim to predict what features such a planet imprints in debris disks undergoing continuous collisional evolution. We discuss the basic equations, analytic approximations and timescales governing collisions, radiation pressure and secular perturbations. In addition, we combine our numerical model of the collisional evolution of the size and spatial distributions in debris disks with the gravitational perturbation by a single planet. We find that the distributions of orbital elements in the disks are strongly dependent on grain sizes. Secular precession is differential with respect to involved semi-major axes and grain sizes. This leads to observable differences between the big grains tracing the parent belt and the small grains in the trailing halo. Observations at different wavelengths can be used to constrain the properties of a possible planet.
- [24] arXiv:1911.07134 [pdf, ps, other]
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Title: Linkage of Geoeffective Stealth CMEs Associated with the Eruption of Coronal Plasma channel and Jet-Like StructureSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Space Physics (physics.space-ph)
We analyze the eruption of a coronal plasma channel (CPC) and an overlying flux rope using \textit{Atmospheric Imaging Assembly/Solar Dynamic Observatory} (AIA/SDO) and \textit{Solar TErrestrial RElations Observatory} (STEREO)-A spacecraft data. The CPC erupted first with its low and very faint coronal signature. Later, above the CPC, a diffuse and thin flux rope also developed and erupted. The spreading CPC further triggered a rotating jet-like structure from the coronal hole lying to its northward end. This jet-like eruption may have evolved due to the interaction between spreading CPC and the open field lines of the coronal hole lying towards its northward foot-point. The CPC connected two small trans-equatorial coronal holes lying respectively in the northern and southern hemisphere on either side of the Equator. These eruptions were collectively associated with the stealth-type CMEs and CME associated with a jet-like eruption. The source region of the stealth CMEs lay between two coronal holes connected by a coronal plasma channel. Another CME was also associated with a jet-like eruption that occurred from the coronal hole in the northern hemisphere. These CMEs evolved without any low coronal signature and yet were responsible for the third strongest geomagnetic storm of Solar cycle 24. These stealth CMEs further merged and collectively passed through the interplanetary space. The compound CME further produced an intense geomagnetic storm (GMS) with Dst index= -176 nT. The $z$-component of the interplanetary magnetic field [$B_{z}$] switched to negative (-18 nT) during this interaction, and simultaneous measurement of the disturbance in the Earth's magnetic field (Kp=7) indicates the onset of the geomagnetic storm.
- [25] arXiv:1911.07150 [pdf, other]
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Title: Elemental abundances distributions in (R, $V_φ$) plane with LAMOST DR5 and Gaia DR2Comments: 21 pages, 26 figuresSubjects: Astrophysics of Galaxies (astro-ph.GA)
Since Gaia DR2 was released, many velocity structures in the disk have been revealed such as large scale ridge-like patterns in the phase space. Both kinematic information and stellar elemental abundances are needed to reveal their evolution history. We have used labels from the APOGEE survey to predict elemental abundances for a huge amount of low resolution spectra from the LAMOST survey. Deep learning with artificial neural networks can automatically draw on physically sensible features in the spectrum for their predictions. Abundances of 12 individual elements: [C/Fe], [N/Fe], [O/Fe], [Mg/Fe], [Al/Fe], [Si/Fe], [S/Fe], [Cl/Fe], [Ca/Fe], [Ti/Fe], [Mn/Fe] and [Ni/Fe] along with basic stellar labels $T_{\textrm{eff}}$, log $g$, metallicity ([M/H] and [Fe/H]) and [$\alpha$/M] for 1 063 386 stars have been estimated. Then those stars were cross matched with Gaia DR2 data to obtain kinematic parameters. We presented distributions of chemical abundances in the $V_{\phi}$ versus \textit{R} coordinate. Our results extend the chemical characterization of the ridges in the (R, $V_{\phi}$) plane to about $R = $13 kpc toward the anticenter direction. In addition, radial elemental abundance gradients for disk stars with abs(\textit{z})$ < 0.5$ kpc are investigated and we fitted a line for median abundance values of bins of stars with galactocentric distance between $R > 7.84$ kpc and $R < 15.84$ kpc. The radial metallicity gradients for disk stars are respectively -0.0475 $\pm $0.0015 for $R < 13.09$ kpc and -0.0173 $\pm $0.0028 for $R < 13.09$ kpc. Gradients for other elemental abundances are also obtained, for example, [$\alpha$/M] gradients for disk stars is 0.0030 $\pm $0.0002.
- [26] arXiv:1911.07240 [pdf, other]
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Title: A charming ICECUBE discover?Comments: 15 pages, 4 figures, updated minimaized version, from earlier arxiv.org/abs/1808.10493v4; Volume 331, Frontier Research in Astrophysics, III (FRAPWS2018)Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Phenomenology (hep-ph)
Last two years high energy neutrino data are studied. The two recent tau neutrino double bang candidate are discussed within their detectability, noise and expected rate. The neutrino flavor distribution mainly favoring equal electron and muon presence, is reminded. The angular distribution of highest muon neutrino tracks is analyzed. Their horizontal strong anisotropy and their remarkable up-down asymmetry, with the absence of clustering, is noticed. The main persistent missing of astrophysical X,gamma sources (as GRB and AGN flaring source) and all the above signatures led us to suggest a dominance of prompt charmed (atmospheric) events able to pollute, to smear and to hide any minor astronomical presence.
- [27] arXiv:1911.07267 [pdf, other]
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Title: On the origin of the peak of the stellar initial mass function: exploring the tidal screening theorySubjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)
Classical theories for the stellar initial mass function (IMF) predict a peak mass which scales with the properties of the molecular cloud. In this work, we explore a new theory proposed by Lee & Hennebelle (2018). The idea is that the tidal field around first Larson cores prevents the formation of other collapsing clumps within a certain radius. The protostar can then freely accrete the gas within this radius. This leads to a peak mass of roughly $10 \, M_{\mathrm{1LC}}$, independent of the parent cloud properties. Using simple analytical arguments, we derive a collapse condition for clumps located close to a protostar. We then study the tidal field and the corresponding collapse condition using a series of numerical simulations. We find that the tidal field around protostars is indeed strong enough to prevent clumps from collapsing unless they have high enough densities. For each newly formed protostar, we determine the region in which tidal screening is dominant. We call this the tidal bubble. The mass within this bubble is our estimate for the final mass of the star. Using this formalism, we are able to construct a very good prediction for the final IMF in our simulations. Not only do we correctly predict the peak, but we are also able to reproduced the high and low mass end of the IMF. We conclude that tidal forces are important in determining the final mass of a star and might be the dominant effect in setting the peak mass of the IMF.
- [28] arXiv:1911.07332 [pdf, ps, other]
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Title: Properties of merger components and remnant in GW170817 using equations of state in finite temperature field theory modelsComments: LaTex, 25 pages including 7 FiguresSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
We investigate gross properties of merger components and remnant in GW170817 using equations of state (EoSs) within the finite temperature field theoretical models. We also adopt finite temperature equations of state in the density dependent hadron field theory such as DD2 EoS and Banik, Hempel and Bandyopadhyay (BHB) EoS involving $\Lambda$ hyperons interacting via $\Phi$ meson popularly known as BHB$\Lambda \phi$ EoS. Properties of merger components are studied using zero temperature EoSs. Particularly we investigate tidal deformabilities and radii of merger components in light of GW170817. An analytical expression relating the radius of merger components and the combined tidal deformability is obtained for binary neutron star masses in the range $1.1M_{\odot}\lesssim M\lesssim 1.6 M_{\odot}$. The upper bound on the tidal deformability gives the upper bound on the radius of merger components 13 km. Next the role of finite temperature on the merger remnant is explored. In this case, we investigate the gravitational and baryon mass, radius, Kepler frequency and moment of inertia of the rigidly rotating remnant for different EoSs at fixed entropy per baryon. The remnant radius is enlarged due to thermal effects compared with the zero temperature case. Consequently it is found that the Kepler frequency is much lower at higher entropy per baryon than that of the case at zero temperature.
- [29] arXiv:1911.07339 [pdf, ps, other]
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Title: Star formation and gas flow history of a dwarf irregular galaxy traced by gas-phase and stellar metallicitiesAuthors: Nao FukagawaComments: 13 pages, 9 figures, accepted for publication in MNRASSubjects: Astrophysics of Galaxies (astro-ph.GA)
Studying the evolution of dwarf galaxies can provide insights into the characteristics of systems that can act as building blocks of massive galaxies. This paper discusses the history of star formation and gas flows (inflow and outflow) of a dwarf irregular galaxy in the Local Group, NGC 6822, from the viewpoint of gas-phase and stellar chemical abundance. Gas-phase oxygen abundance, stellar metallicity distribution and gas fraction data are compared to chemical evolution models in which continuous star formation and gas flows are assumed. If the galaxy is assumed to be a closed or an accretion-dominated system where steeper stellar initial mass functions are allowed, the observed gas-phase oxygen abundance and gas fraction can be explained simultaneously; however metallicity distributions predicted by the models seem to be inconsistent with the observed distribution, which suggests that the star formation, gas flows and/or chemical enrichment are more complex than assumed by the models. When NGC 6822 is assumed to be a system dominated by outflow, the observed values of gas-phase oxygen abundance and gas fraction can be explained, and the metallicity distributions predicted by some of the models are also roughly consistent with the observed distribution in the metallicity range of -2.0<[Fe/H]<-0.5. It should be noted that this result does not necessarily mean that the accretion of gas is completely ruled out. More observables, such as chemical abundance ratios, and detailed modelling may provide deeper insight into the evolution of the system.
- [30] arXiv:1911.07350 [pdf, other]
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Title: A dynamical evolution of GRB-Afterglows in a new generic modelComments: 15 pages,9 figuresSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
A new model using a general expression of the radiation energy and explaining the dynamics of the afterglows is proposed. It is shown that this model is suitable for the ultra-relativistic and non-relativistic phases as well as the study of radiative and adiabatic fireballs.
- [31] arXiv:1911.07355 [pdf, other]
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Title: An extremely low-density and temperate giant exoplanetAuthors: A. Santerne, L. Malavolta, M. R. Kosiarek, F. Dai, C. D. Dressing, X. Dumusque, N. C. Hara, T. A. Lopez, A. Mortier, A. Vanderburg, V. Adibekyan, D. J. Armstrong, D. Barrado, S. C. C. Barros, D. Bayliss, D. Berardo, I. Boisse, A. S. Bonomo, F. Bouchy, D. J. A. Brown, L. A. Buchhave, R. P. Butler, A. Collier Cameron, R. Cosentino, J. D. Crane, I. J. M. Crossfield, M. Damasso, M. R. Deleuil, E. Delgado Mena, O. Demangeon, R. F. Díaz, J.-F. Donati, P. Figueira, B. J. Fulton, A. Ghedina, A. Harutyunyan, G. Hébrard, L. A. Hirsch, S. Hojjatpanah, A. W. Howard, H. Isaacson, D. W. Latham, J. Lillo-Box, M. López-Morales, C. Lovis, A. F. Martinez Fiorenzano, E. Molinari, O. Mousis, C. Moutou, C. Nava, L. D. Nielsen, H. P. Osborn, E. A. Petigura, D. F. Phillips, D. L. Pollacco, E. Poretti, et al. (15 additional authors not shown)Comments: Preprint submitted to Nature Astronomy. The results have not been peer-reviewed yet. Supplementary informations available as ancillary fileSubjects: Earth and Planetary Astrophysics (astro-ph.EP)
Transiting extrasolar planets are key objects in the study of the formation, migration, and evolution of planetary systems. In particular, the exploration of the atmospheres of giant planets, through transmission spectroscopy or direct imaging, has revealed a large diversity in their chemical composition and physical properties. Studying these giant planets allows one to test the global climate models that are used for the Earth and other solar system planets. However, these studies are mostly limited either to highly-irradiated transiting giant planets or directly-imaged giant planets at large separations. Here we report the physical characterisation of the planets in a bright multi-planetary system (HIP41378) in which the outer planet, HIP41378 f is a Saturn-sized planet (9.2 $\pm$ 0.1 R$_\oplus$) with an anomalously low density of 0.09 $\pm$ 0.02 g cm$^{-3}$ that is not yet understood. Its equilibrium temperature is about 300 K. Therefore, it represents a planet with a mild temperature, in between the hot Jupiters and the colder giant planets of the Solar System. It opens a new window for atmospheric characterisation of giant exoplanets with a moderate irradiation, with the next-generation space telescopes such as JWST and ARIEL as well as the extremely-large ground-based telescopes. HIP41378 f is thus an important laboratory to understand the effect of the irradiation on the physical properties and chemical composition of the atmosphere of planets.
- [32] arXiv:1911.07370 [pdf, other]
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Title: Modeling Kelvin-Helmholtz instability-driven turbulence with hybrid simulations of Alfvénic turbulenceAuthors: Luca Franci, Julia E. Stawarz, Emanuele Papini, Petr Hellinger, Takuma Nakamura, David Burgess, Simone Landi, Andrea Verdini, Lorenzo Matteini, Robert Ergun, Olivier Le Contel, Per-Arne LindqvistComments: 11 pages, 6 figures, submitted to The Astrophysical JournalSubjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
Magnetospheric Multiscale (MMS) observations of plasma turbulence generated by a Kelvin-Helmholtz (KH) event at the Earth's magnetopause are compared with a high-resolution two-dimensional (2D) hybrid direct numerical simulation (DNS) of decaying plasma turbulence driven by large-scale balanced Alfv\'enic fluctuations. The simulation, set up with four observation-driven physical parameters (ion and electron betas, turbulence strength, and injection scale) exhibits a quantitative agreement on the spectral, intermittency, and cascade-rate properties with in situ observations, despite the different driving mechanisms. Such agreement demonstrates a certain universality of the turbulent cascade from magnetohydrodynamic (MHD) to sub-ion scales, whose properties are mainly determined by the selected parameters, also indicating that the KH instability-driven turbulence has a quasi-2D nature. The validity of the Taylor hypothesis in the sub-ion spatial range suggests that the fluctuations at sub-ion scales have predominantly low frequencies, consistent with a kinetic Alfv\'en wave-like nature or with quasi-static structures. Finally, the third-order structure function analysis indicates that the cascade rate of the turbulence generated by a KH event in the magnetopause is an order of magnitude larger than in the ambient magnetosheath.
- [33] arXiv:1911.07371 [pdf, other]
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Title: Unified Superfluid Dark SectorAuthors: Elisa G. M. FerreiraComments: Invited talk at the XI Symposium Quantum Theory and Symmetries (QTS-XI), Montreal, Canada, July 2019; to appear in the proceedings (CRM Series on Mathematical Physics, Springer), Eds. Richard MacKenzie, Manu Paranjape, Zora Thomova, Pavel Winternitz, William Witczak-KrempaSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc)
In this talk I present a new model of a unified dark sector, where late-time cosmic acceleration emerges from the dark matter (DM) superfluid framework. We will start by reviewing the dark matter superfluid model and show how it describes the dynamics of DM in large and small scales. Then we will show that if the superfluid consists of a mixture of two distinguishable states with a small energy gap, such as the ground state and an excited state of DM, interacting through a contact interaction a new dynamics of late-time accelerated expansion emerges in this system, without the need of dark energy, coming from a universe containing only this two-state DM superfluid. I will show the expansion history and growth of linear perturbations, and show that the difference in the predicted growth rate in comparison to $\Lambda$CDM is significant at late times.
- [34] arXiv:1911.07397 [pdf, ps, other]
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Title: Spectro-polarimetric Observations at the NVST: I. Instrumental Polarization Calibration and Primary MeasurementsAuthors: Jun-Feng Hou, Zhi Xu, Shu Yuan, Yu-Chao Chen, Jian-Guo Peng, Dong-Guang Wang, Jun Xu, Yuan-Yong Deng, Zhen-Yu Jin, Kai-Fan Ji, Zhong LiuComments: 17pages, 9 figures,accepted by Research in Astronomy and AstrophysicsSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Instrumentation and Methods for Astrophysics (astro-ph.IM)
This paper is devoted to the primary spectro-polarimetric observation performed at the New Vacuum Solar Telescope of China since 2017, and our aim is to precisely evaluate the real polarimetric accuracy and sensitivity of this polarimetry by using full Stokes spectro-polarimetric observations of the photospheric line Fe I 532.4 nm. In the work, we briefly describe the salient characteristic of the NVST as a polarimeter in technology and then characterize its instrumental polarization based on the operation in 2017 and 2019. It is verified that the calibration method making use of the instrumental polarization calibration unit (ICU) is stable and credible. The calibration accuracy can reach up to 3$\times 10^{-3}$ . Based on the scientific observation of the NOAA 12645 on April 5th, 2017, we estimate that the residual cross-talk from Stokes $I$ to Stokes $Q$, $U$ and $V$, after the instrumental polarization calibration, is about 4$\times10^{-3}$ on average, which is consistent with the calibration accuracy and close to the photon noise. The polarimetric sensitivity (i.e., the detection limit) for polarized light is of the order of $10^{-3}$ with an integration time over 20 seconds. Slow modulation rate is indeed an issue for the present system. The present NVST polarimeter is expected to be integrated with an high-order adaptive optics system and a field scanner to realize 2D magnetic field vector measurements in the following instrumentation update.
- [35] arXiv:1911.07438 [pdf, other]
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Title: Detection of UHE gamma rays from the Crab Nebula: Physical ImplicationsComments: 8 pages, 5 figures, MNRAS acceptedSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
The Crab Nebula is an extreme particle accelerator boosting the energy of electrons up to a few PeV ($10^{15} \ \rm eV$), close to the maximum energy allowed by theory. The physical conditions in the acceleration site and the nature of the acceleration process itself remain highly uncertain. The key information about the highest energy accelerated particles is contained in the synchrotron and inverse Compton (IC) channels of radiation at energies above 1~MeV and 100~TeV, respectively. The recent report of detection of ultra-high energy gamma-ray signal from the Crab Nebula up to 300~TeV allows one to determine the energy distribution of the highest energy electrons and to derive the magnetic field strength in the acceleration region, $B\leq120\rm\,\mu G$, in a parameter-free way. This estimate brings new constraints on the properties of non-thermal particle distributions and puts important constraints on the MHD models for the Crab Nebula, in particular on the feasible magnetization and anisotropy of the pulsar wind. The calculations of synchrotron and IC emission show that future observations with instruments allowing detection of the Crab Nebula above 300~TeV and above 1~MeV will clarify the conditions allowing acceleration of electrons beyond PeV energies in the Crab Nebula. In particular, one will (1) verify the hypothetical multi-component composition of the electron energy distribution, and (2) determine the magnetic field strength in the regions responsible for the acceleration of PeV electrons.
- [36] arXiv:1911.07441 [pdf, other]
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Title: Modelling the interaction between relativistic and non-relativistic winds in binary pulsar systems: strong magnetization of the pulsar windAuthors: Sergey V. Bogovalov, Dmitry Khangulyan, Alexander V. Koldoba, Galina V. Ustyugova, Felix AharonianComments: 8 pages, 5 figures, MNRAS acceptedJournal-ref: 2019MNRAS.490.3601BSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
We present a numerical study of the properties of the flow produced by the collision of a magnetized anisotropic pulsar wind with the circumbinary environment. We focus on studying the impact of the high wind magnetization on the geometrical structure of the shocked flow. This work is an extension of our earlier studies that focused on a purely hydrodynamic interaction and weak wind magnetization. We consider the collision in the axisymmetric approximation, that is, the pulsar rotation axis is assumed to be oriented along the line between the pulsar and the optical star. The increase of the magnetization results in the expansion of the opening cone in which the shocked pulsar wind propagates. This effect is explained in the frameworks of the conventional theory of collimation of magnetized winds. This finding has a direct implication for scenarios that involve Doppler boosting as the primary mechanism behind the GeV flares detected with the Fermi/LAT from PSR B1259-63/LS2883. The maximum enhancement of the apparent emission is determined by the ratio of $4\pi$ to the solid in which the shocked pulsar wind propagates. Our simulations suggest that this enhancement factor is decreased by the impact of the magnetic field.
- [37] arXiv:1911.07442 [pdf, ps, other]
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Title: Probing Small Scale Primordial Power Spectrum with 21cm Line Global SignalComments: 20 pages, 8 figures, one columnSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph)
We argue that the global signal of neutral hydrogen 21cm line can be a powerful probe of primordial power spectrum on small scales. Since the amplitude of small scale primordial fluctuations is important to determine the early structure formation and the timing when the sources of Lyman ${\alpha}$ photons are produced, they in turn affect the neutral hydrogen 21cm signal. We show that the information of the position of the absorption trough can severely constrain the small scale amplitude of primordial fluctuations once astrophysical parameters relevant to the 21cm signal are fixed. We also discuss how the uncertainties of astrophysical parameters affect the constraints.
- [38] arXiv:1911.07457 [pdf, other]
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Title: Calibrating the power of relativistic jetsAuthors: L. Foschini, M. L. Lister, T. Hovatta, Y. Y. Kovalev, P. Romano, S. Vercellone, A. Lähteenmäki, T. K. Savolainen, M. Tornikoski, E. Angelakis, M. Berton, V. Braito, S. Ciroi, M. Kadler, P. R. BurdComments: 7 pages, 4 figures. Poster presented at High Energy Phenomena in Relativistic Outflows (HEPRO) VII, Barcelona (Spain), July 9-12, 2019Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Astrophysics of Galaxies (astro-ph.GA)
There are several methods to calculate the radiative and kinetic power of relativistic jets, but their results can differ by one or two orders of magnitude. Therefore, it is necessary to perform a calibration of the jet power, to understand the reasons for these differences (whether wrong hypotheses or intrinsic source variability), and if it is possible to converge to a reliable measurement of this physical quantity. We present preliminary results of a project aimed at calibrating the power of relativistic jets in active galactic nuclei (AGN) and X-ray binaries (XRB). We started by selecting all the AGN associations with known redshift in the Fourth Fermi LAT Gamma-Ray Catalog (4FGL). We then calculated the radiative and/or kinetic powers from available data or we extracted this information from literature. We compare the values obtained for overlapping samples and highlight early conclusions.
- [39] arXiv:1911.07519 [pdf, other]
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Title: Asteroseismology of the Multiplanet System K2-93Authors: Mikkel N. Lund, Emil Knudstrup, Victor Silva Aguirre, Sarbani Basu, Ashley Chontos, Carolina Von Essen, William J. Chaplin, Allyson Bieryla, Luca Casagrande, Andrew Vanderburg, Daniel Huber, Stephen R. Kane, Simon Albrecht, David W. Latham, Guy R. Davies, Juliette C. Becker, Joseph E. RodriguezComments: 15 pages, 9 figures, accepted for publication in the Astronomical JournalSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP)
We revisit the analysis of the bright multiplanet system K2-93, discovered with data taken by the K2 mission. This system contains five identified planets ranging in size from sub-Neptune to Jupiter size. The K2 data available at the discovery of the system only showed single transits for the three outer planets, which allowed weak constraints to be put on their periods. As these planets are interesting candidates for future atmospheric studies, a better characterization of the host star and tighter constraints on their orbital periods are essential. Using new data from the K2 mission taken after the discovery of the system, we perform an asteroseismic characterization of the host star. We are able to place strong constraints on the stellar parameters and obtain a value for the stellar mass of $1.22^{+0.03}_{-0.02}\, \rm M_{\odot}$, a stellar radius of $1.30\pm 0.01\, \rm R_{\odot}$, and an age of $2.07^{+0.36}_{-0.27}$ Gyr. Put together with the additional transits identified for two of the three outer planets, we constrain the orbital periods of the outer planets and provide updated estimates for the stellar reflex velocities induced by the planets.
- [40] arXiv:1911.07540 [pdf]
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Title: Low Order Adaptive Optics with Very Faint Reference StarsAuthors: Craig MackayComments: 12 pages, 10 figures, 1 table. Presented at the Scientific Detector Workshop, Baltimore, 2017Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
It is widely believed that adaptive optics only has a role in correcting turbulent wavefronts on large telescopes using very bright reference stars. Unfortunately these are very scarce and many astronomical targets require wavefront correction to work over much of the sky. We therefore need to be able to use very much fainter reference objects. Laser guide stars in principle can allow 0.1 arcsecond resolution but have a number of severe technical problems that limit their application. Our aims are to provide imaging at even higher resolution than Hubble. Lucky Imaging completely eliminates the tip-tilt errors in astronomical wavefront detection. Most of the power that remains is in low order, large scale structures. These may be detected with high sensitivity using photon-counting EMCCD detectors working at high frame rate, up to ~100Hz. With a new design of curvature wavefront sensor, wavefront errors may be measured and corrected to give near diffraction-limited performance on large groundbased telescopes in the visible. Reference stars (and reference compact galaxies) fainter than I~17.5 mag may be used routinely. This paper will describe how these work, what detector and other hardware is needed and what software should be used to measure the wavefront errors and drive deformable mirror hardware. The software techniques that are used are those routinely applied for MRI and CT imaging. They are fast and relatively easy to implement. The net effect is that imaging systems can be constructed that improve substantially over Hubble resolution from the ground for a relatively modest sum of money.
- [41] arXiv:1911.07544 [pdf]
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Title: GravityCam: Wide-field Imaging Surveys in the Visible from the GroundAuthors: C. Mackay, M. Dominik, I.A. Steele, C. Snodgrass, U.G. Jørgensen, J. Skottfelt, K. Stefanov, B. Carry, F. Braga-Ribas, A. Doressoundiram, V.D. Ivanov, P. Gandhi, D.F. Evans, M. Hundertmark, S. Serjeant, S. OrtolaniComments: 13 pages, 9 figures. Paper presented at the Scientific Detector Workshop, Baltimore, 2017Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
GravityCam is a new concept of ground-based imaging instrument capable of delivering significantly sharper images from the ground than is normally possible without adaptive optics. Advances in optical and near infrared imaging technologies allow images to be acquired at high speed without significant noise penalty. Aligning these images before they are combined can yield a 3-5 fold improvement in image resolution. By using arrays of such detectors, survey fields may be as wide as the telescope optics allows. We describe the instrument and detail its application to accelerate greatly the rate of detection of Earth size planets by gravitational microlensing. GravityCam will improve substantially the quality of weak shear studies of dark matter distribution in distant clusters of galaxies. An extensive microlensing survey will also provide a vast dataset for asteroseismology studies, and GravityCam promises to generate a unique data set on the population of the Kuiper belt and possibly the Oort cloud.
- [42] arXiv:1911.07550 [pdf, other]
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Title: Calibration of RADMON Radiation Monitor Onboard Aalto-1 CubeSatAuthors: Philipp Oleynik (1), Rami Vainio (1), Arttu Punkkinen (1), Oleksiy Dudnik (3), Jan Gieseler (1), Hannu-Pekka Hedman (2), Heli Hietala (1), Edward Hæggström (5), Petri Niemelä (4), Juhani Peltonen (1), Jaan Praks (4), Risto Punkkinen (2), Tero Säntti (2), Eino Valtonen (1) ((1) Department of Physics and Astronomy of the University of Turku, (2) Department of Future Technologies of the University of Turku, (3) Institute of Radio Astronomy National Academy of Sciences of Ukraine, (4) School of Electrical Engineering of Aalto University, (5) Department of Physics of the University of Helsinki)Comments: 27 pages, 9 figuresSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Instrumentation and Detectors (physics.ins-det)
RADMON is a small radiation monitor designed and assembled by students of the University of Turku and the University of Helsinki. It is flown on-board Aalto-1, a 3-unit CubeSat in low Earth orbit at about 500 km altitude. The detector unit of the instrument consists of two detectors, a Si solid-state detector and a CsI(Tl) scintillator, and utilizes the \textDelta{E}-E technique to determine the total energy and species of each particle hitting the detector. We present the results of the on-ground and in-flight calibration campaigns of the instrument, as well as the characterization of its response through extensive simulations within the Geant4 framework. The overall energy calibration margin achieved is about 5\%. The full instrument response to protons and electrons is presented and the issue of proton contamination of the electron channels is quantified and discussed.
- [43] arXiv:1911.07552 [pdf, other]
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Title: The newborn black hole in GRB 191014C manifests that is aliveComments: Submitted on 18 November 2019Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc)
The popular view that BHs (BH) are dark objects, a sink of energy rather than an energy source, arises from three assumptions, that they are (i) in vacuum, (ii) in an asymptotically flat space-time, and (iii) stationary. As a result, despite theoretical efforts, the search for an efficient mechanism to extract the energy from a BH, able to power the most energetic astrophysical sources, gamma-ray bursts (GRBs) and active galactic nuclei (AGNs), has been unsuccessful for decades. Here we show that an extremely efficient electrodynamical process of BH energy extraction occurs in the "inner engine", violating the assumptions (i)-(iii), composed of a rotating BH in a background of very-low-density ionized plasma and a test, ordered magnetic field, aligned and parallel with the rotation axis. It operates in a sequence of "quantized" steps, each emitting a "blackholic quantum", initially of energy $10^{37}$ erg, over a timescale of $10^{-14}$ s, leading to GeV and TeV photons with luminosities of $10^{51}$ erg s$^{-1}$. Every event takes away only $10^{-16}$ of the extractable energy of the BH, allowing the "inner engine" to operate for thousands of years or more. The blackholic quantum of energy, with such a characteristic short timescale, is emitted in the entire Universe in view of the ubiquitous and homogeneous cosmological presence of GRBs. This suggests the intriguing possibility that, rather than representing the end of life, BHs may have a relevant role in the evolution of life in our Universe.
- [44] arXiv:1911.07568 [pdf, other]
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Title: Potential Connection Between IceCube Neutrinos and Late Bumps in Gamma-Ray BurstsComments: 8 pages, 4 figures and 1 tableSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Phenomenology (hep-ph)
IceCube has detected many TeV-PeV neutrinos, but their astrophysical origins remain largely unknown. Motivated by the observed late-time X-ray/optical bumps in some gamma-ray bursts (GRBs), we examine the correlation between IceCube neutrinos and GRBs allowing delayed neutrinos $\sim$ days after the prompt gamma rays and suggest a few potentially correlated events. We show in a model-independent way that GRB sites capable of producing late $\sim$ PeV neutrinos should be nonrelativistic or mildly relativistic. We estimate the diffuse neutrino flux from such sources and find that they can possibly account for a few IceCube events. Future observations of high-energy neutrinos and late-time GRB afterglows can further test the above proposed connection.
- [45] arXiv:1911.07688 [pdf, other]
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Title: emcee v3: A Python ensemble sampling toolkit for affine-invariant MCMCAuthors: Daniel Foreman-Mackey, Will M. Farr, Manodeep Sinha, Anne M. Archibald, David W. Hogg, Jeremy S. Sanders, Joe Zuntz, Peter K. G. Williams, Andrew R. J. Nelson, Miguel de Val-Borro, Tobias Erhardt, Ilya Pashchenko, Oriol Abril PlaComments: Published in the Journal for Open Source SoftwareJournal-ref: Journal of Open Source Software, 2 4(43), 1864 (2019)Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Computation (stat.CO)
emcee is a Python library implementing a class of affine-invariant ensemble samplers for Markov chain Monte Carlo (MCMC). This package has been widely applied to probabilistic modeling problems in astrophysics where it was originally published, with some applications in other fields. When it was first released in 2012, the interface implemented in emcee was fundamentally different from the MCMC libraries that were popular at the time, such as PyMC, because it was specifically designed to work with "black box" models instead of structured graphical models. This has been a popular interface for applications in astrophysics because it is often non-trivial to implement realistic physics within the modeling frameworks required by other libraries. Since emcee's release, other libraries have been developed with similar interfaces, such as dynesty (Speagle 2019). The version 3.0 release of emcee is the first major release of the library in about 6 years and it includes a full re-write of the computational backend, several commonly requested features, and a set of new "move" implementations.
- [46] arXiv:1911.07713 [pdf, ps, other]
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Title: MKT J170456.2-482100: the first transient discovered by MeerKATAuthors: L. N. Driessen (1), I. McDonald (1), D. A. H. Buckley (2), M. Caleb (1), E. J. Kotze (2 and 20), S. B. Potter (2), K .M. Rajwade (1), A. Rowlinson (3 and 4), B. W. Stappers (1), E. Tremou (5), P. A. Woudt (6), R. P. Fender (6 and 7), R. Armstrong (6 and 8), P. Groot (2 and 6 and 9), I. Heywood (7 and 10), A. Horesh (11), A. J. van der Horst (12 and 13), E. Koerding (9), V. A. McBride (2 and 14 and 15), J. C. A. Miller-Jones (16), K. P. Mooley (17 and 18 and 19), R. A. M. J. Wijers (3) ((1) Jodrell Bank Centre for Astrophysics, (2) South African Astronomical Observatory, (3) Anton Pannekoek Institute, (4) Netherlands Institute for Radio Astronomy (ASTRON), (5) AIM CEA CNRS Universite Paris Diderot, (6) Inter-University Institute for Data Intensive Astronomy, (7) Department of Physics and Astrophysics the University of Oxford, (8) South African Radio Astronomy Observatory, (9) Department of Astrophysics/IMAPP, (10) Department of Physics and Electronics Rhodes University, (11) Racah Institute of Physics at the Hebrew University of Jerusalem, (12) Department of Physics at the George Washington University, (13) Astronomy Physics and Statistics Institute of Sciences (APSIS), (14) Department of Astronomy at the University of Cape Town, (15) IAU Office of Astronomy for Development, (16) International Centre for Radio Astronomy Research, (17) Department of Physics at the University of Oxford, (18) National Radio Astronomy Observatory, (19) Caltech, (20) Southern African Large Telescope)Comments: 16 pages, 12 figures, 7 tablesSubjects: Solar and Stellar Astrophysics (astro-ph.SR); High Energy Astrophysical Phenomena (astro-ph.HE)
We report the discovery of the first transient with MeerKAT, MKT J170456.2$-$482100, discovered in ThunderKAT images of the low mass X-ray binary GX339$-$4. MKT J170456.2$-$482100 is variable in the radio, reaching a maximum flux density of $0.71\pm0.11\,\mathrm{mJy}$ on 2019 Oct 12, and is undetected in 15 out of 48 ThunderKAT epochs. MKT J170456.2$-$482100 is coincident with the chromospherically active K-type sub-giant TYC 8332-2529-1, and $\sim18\,\mathrm{years}$ of archival optical photometry of the star shows that it varies with a period of $21.25\pm0.04\,\mathrm{days}$. The shape and phase of the optical light curve changes over time, and we detect both X-ray and UV emission at the position of MKT J170456.2$-$482100, which may indicate that TYC 8332-2529-1 has large star spots. Spectroscopic analysis shows that TYC 8332-2529-1 is in a binary, and has a line-of-sight radial velocity amplitude of $43\,\mathrm{km\,s^{-1}}$. We also observe a spectral feature in anti-phase with the K-type sub-giant, with a line-of-sight radial velocity amplitude of $\sim12\pm10\,\mathrm{km\,s^{-1}}$, whose origins cannot currently be explained. Further observations and investigation are required to determine the nature of the MKT J170456.2$-$482100 system.
- [47] arXiv:1911.07734 [pdf, other]
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Title: SN 2017cfd: A Normal Type Ia Supernova Discovered Very YoungAuthors: Xuhui Han, WeiKang Zheng, Benjamin E. Stahl, Jamison Burke, Jozsef Vinko, Thomas de Jaeger, Thomas G. Brink, Borbala Cseh, Daichi Hiramatsu, D. Andrew Howell, Bernadett Ignacz, Reka Konyves-Toth, Mate Krezinger, Curtis McCully, Andras Ordasi, Dora Pinter, Krisztian Sarneczky, Robert Szakats, Kevin Tang, Krisztian Vida, Jing Wang, Jianyan Wei, J. Craig Wheeler, Liping Xin, Alexei V. FilippenkoComments: 10 pages, 7 figures, 3 tablesSubjects: Solar and Stellar Astrophysics (astro-ph.SR); High Energy Astrophysical Phenomena (astro-ph.HE)
The Type~Ia supernova (SN~Ia) 2017cfd in IC~0511 (redshift z = 0.01209+- 0.00016$) was discovered by the Lick Observatory Supernova Search 1.6+-0.7 d after the fitted first-light time (FFLT; 15.2 d before B-band maximum brightness). Photometric and spectroscopic follow-up observations show that SN~2017cfd is a typical, normal SN~Ia with a peak luminosity MB ~ -19.2+-0.2 mag, Delta m15(B) = 1.16 mag, and reached a B-band maximum ~16.8 d after the FFLT. We estimate there to be moderately strong host-galaxy extinction (A_V = 0.39 +- 0.03 mag) based on MLCS2k2 fitting. The spectrum reveals a Si~II lambda 6355 velocity of ~11,200 kms at peak brightness. The analysis shows that SN~2017cfd is a very typical, normal SN Ia in nearly every aspect. SN~2017cfd was discovered very young, with multiband data taken starting 2 d after the FFLT, making it a valuable complement to the currently small sample (fewer than a dozen) of SNe~Ia with color data at such early times. We find that its intrinsic early-time (B - V)0 color evolution belongs to the "blue" population rather than to the distinct "red" population. Using the photometry, we constrain the companion star radius to be < 2.5 R_sun, thus ruling out a red-giant companion.
- [48] arXiv:1911.07754 [pdf, other]
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Title: Understanding parameter differences between analyses employing nested data subsetsComments: 7 pages, 3 figuresSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
We provide an analytical argument for understanding the likely nature of parameter shifts between those coming from an analysis of a dataset and from a subset of that dataset, assuming differences are down to noise and any intrinsic variance alone. This gives us a measure against which we can interpret changes seen in parameters and make judgements about the coherency of the data and the suitability of a model in describing those data.
- [49] arXiv:1911.07766 [pdf, other]
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Title: Co-production of light and heavy $r$-process elements via fission depositionSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
We apply for the first time fission yields determined across the chart of nuclides from the macroscopic-microscopic theory of the Finite Range Liquid Drop Model (FRLDM) to simulations of rapid neutron capture ($r$-process) nucleosynthesis. With the fission rates and yields derived within the same theoretical framework utilized for other relevant nuclear data, our results are the most consistent $r$-process calculations applying macroscopic-microscopic nuclear theory to date. The yields from this model are wide for nuclei with extreme neutron excess. We show that these wide distributions of neutron-rich nuclei, and particularly the asymmetric yields for key species which fission at late times in the $r$ process, can contribute significantly to the abundances of the lighter heavy elements, specifically the light precious metals palladium and silver. Since these asymmetric yields correspondingly also deposit into the lanthanide region, we consider the possible evidence for co-production by comparing our nucleosynthesis results directly with the trends in the elemental ratios of metal-poor stars rich in $r$-process material. We show that for $r$-process enhanced stars palladium over europium and silver over europium display mostly flat trends suggestive of co-production and compare to the lanthanum over europium trend which is often used to justify robustness arguments in the lanthanide region. We find that such robustness arguments may be extendable down to palladium and heavier and demonstrate that fission deposition is a mechanism by which such a universality or robustness can be achieved.
- [50] arXiv:1911.07772 [pdf, ps, other]
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Title: An improved multi-ridge fitting method for ring-diagram helioseismic analysisComments: Accepted for publication in A&ASubjects: Solar and Stellar Astrophysics (astro-ph.SR)
Context: There is a wide discrepancy in current estimates of the strength of convection flows in the solar interior obtained using different helioseismic methods applied to observations from SDO/HMI. The cause for these disparities is not known. Aims: As one step in the effort to resolve this discrepancy, we aim to characterize the multi-ridge fitting code for ring-diagram helioseismic analysis that is used to obtain flow estimates from local power spectra of solar oscillations. Methods: We updated the multi-ridge fitting code developed by Greer et al.(2014) to solve several problems we identified through our inspection of the code. In particular, we changed the merit function to account for the smoothing of the power spectra, model for the power spectrum, and noise estimates. We used Monte Carlo simulations to generate synthetic data and to characterize the noise and bias of the updated code by fitting these synthetic data. Results: The bias in the output fit parameters, apart from the parameter describing the amplitude of the p-mode resonances in the power spectrum, is below what can be measured from the Monte-Carlo simulations. The amplitude parameters are underestimated; this is a consequence of choosing to fit the logarithm of the averaged power. We defer fixing this problem as it is well understood and not significant for measuring flows in the solar interior. The scatter in the fit parameters from the Monte-Carlo simulations is well-modeled by the formal error estimates from the code. Conclusions: We document and demonstrate a reliable multi-ridge fitting method for ring-diagram analysis. The differences between the updated fitting results and the original results are less than one order of magnitude and therefore we suspect that the changes will not eliminate the aforementioned orders-of-magnitude discrepancy in the amplitude of convective flows in the solar interior.
- [51] arXiv:1911.07813 [pdf, other]
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Title: Turbulence in stably stratified radiative zoneAuthors: F. LignièresComments: 30 pages, 12 figures, Proceedings of the Evry Schatzman School 2018. Edited by M. Rieutord, I. Baraffe, Y. Lebreton. EDP Sciences Proceedings, to appearSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Fluid Dynamics (physics.flu-dyn)
The topic of turbulent transport in a stellar radiative zone is vast and poorly understood. Many physical processes can potentially drive turbulence in stellar radiative zone but the limited observational constraints and the uncertainties in modelling turbulent transport make it difficult to identify the most relevant one. Here, we focus on the effect of stable stratification on the radial turbulent transport of chemicals and more particularly on the case where the turbulence is driven by a radial shear. Results of numerical simulations designed to test phenomenological models of turbulent transport will be presented. While this may appears little ambitious, stable stratification will influence the radial turbulent transport whatever the mechanism that drives the turbulent motions and the present considerations should be useful for these other mechanism too.
- [52] arXiv:1911.07824 [pdf, ps, other]
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Title: Cosmological Simulation of Galaxy Groups and Clusters-I: Global Effect of Feedback from Active Galactic NucleiAuthors: Rudrani Kar Chowdhury, Suchetana Chatterjee, Anto . I. Lonappan, Nishikanta Khandai, Tiziana DiMatteoComments: 11 pages, 8 figures, Accepted for publication at Astrophysical JournalSubjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
In this study we quantify the properties of the gas and dark matter around active galactic nuclei (AGN) in simulated galaxy groups and clusters and analyze the effect of AGN feedback on the surrounding intra-cluster (group) medium. Our results suggest downsizing of AGN luminosity with host halo mass, supporting the results obtained from clustering studies of AGN. By examining the temperature and density distribution of the gas in the vicinity of AGN we show that due to feedback from the central engine, the gas gets displaced from the centre of the group/cluster resulting in a reduction of the density but an enhancement of temperature. We show that these effects are pronounced at both high and low redshifts and propose new observables to study the effect of feedback in higher redshift galaxies. We also show that the average stellar mass is decreased in halos in the presence of AGN feedback confirming claims from previous studies. Our work for the first time uses a fully cosmological-hydrodynamic simulation to evaluate the global effects of AGN feedback on their host dark matter halos as well as galaxies at scales of galaxy groups and clusters.
- [53] arXiv:1911.07825 [pdf, other]
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Title: Know thy star, know thy planet: Chemo-kinematically characterizing TESS targetsComments: 19 pages, accepted in MNRAS, catalog is available here: this http URLSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP); Astrophysics of Galaxies (astro-ph.GA)
The Transiting Exoplanet Survey Satellite (TESS) has already begun to discover what will ultimately be thousands of exoplanets around nearby cool bright stars. These potential host stars must be well-understood to accurately characterize exoplanets at the individual and population levels. We present a catalogue of the chemo-kinematic properties of 2,218,434 stars in the TESS Candidate Target List using survey data from Gaia DR2, APOGEE, GALAH, RAVE, LAMOST, and photometrically-derived stellar properties from SkyMapper. We compute kinematic thin disc, thick disc, and halo membership probabilities for these stars and find that though the majority of TESS targets are in the thin disc, 4% of them reside in the thick disc and <1% of them are in the halo. The TESS Objects of Interest in our sample also display similar contributions from the thin disc, thick disc, and halo with a majority of them being in the thin disc. We also explore metallicity and [alpha/Fe] distributions for each Galactic component and show that each cross-matched survey exhibits metallicity and [alpha/Fe] distribution functions that peak from higher to lower metallicity and lower to higher [alpha/Fe] from the thin disc to the halo. This catalogue will be useful to explore planet occurrence rates, among other things, with respect to kinematics, component-membership, metallicity, or [alpha/Fe].
- [54] arXiv:1911.07832 [pdf, other]
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Title: Angular Correlation Function Estimators Accounting for Contamination from Probabilistic Distance MeasurementsComments: 20 pages and 4 appendices (17 pages). 13 figures. Submitted to ApJ, with this version revised in response to comments from the refereeSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
With the advent of surveys containing millions to billions of galaxies, it is imperative to develop analysis techniques that utilize the available statistical power. In galaxy clustering, even small sample contamination arising from distance uncertainties can lead to large artifacts, which the standard estimator does not account for. We first introduce a formalism, termed decontamination, that corrects for sample contamination by utilizing the observed cross-correlations in the contaminated samples; this corrects any correlation function estimator for contamination. Using this formalism, we present a new estimator that uses the standard estimator to measure correlation functions in the contaminated samples but then corrects for contamination. We also introduce a weighted estimator that assigns each galaxy a weight in each redshift bin based on its probability of being in that bin. We demonstrate that these estimators effectively recover the true correlation functions and their covariance matrices. Our estimators can correct for sample contamination caused by misclassification between object types as well as photometric redshifts; they should be particularly helpful for studies of galaxy evolution and baryonic acoustic oscillations, where forward-modeling the clustering signal using the contaminated redshift distribution is undesirable.
Cross-lists for Tue, 19 Nov 19
- [55] arXiv:1911.06315 (cross-list from gr-qc) [pdf, ps, other]
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Title: Primordial universe with the running cosmological constantComments: 22 pages, 6 figures, 1 tableSubjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Theory (hep-th)
Theoretically, the running of the cosmological constant in the IR region is not ruled out. On the other hand, from the QFT viewpoint, the energy released due to the variation of the cosmological constant in the late universe cannot go to the matter sector. For this reason, the phenomenological bounds on such a running are not sufficiently restrictive. The situation can be different in the early universe when the gravitational field was sufficiently strong to provide an efficient creation of particles from the vacuum. We develop a framework for systematically exploring this possibility. It is supposed that the running occurs in the epoch when the Dark Matter already decoupled and is expanding adiabatically, while baryons are approximately massless and can be abundantly created from vacuum due to the decay of vacuum energy. By using the handy model of Reduced Relativistic Gas for describing the Dark Matter, we consider the dynamics of both cosmic background and linear perturbations and evaluate the impact of the vacuum decay on the matter power spectrum and to the first CMB peak. Additionally, using the combined data of CMB+BAO+SNIa we find the best fit values for the free parameters of our model.
- [56] arXiv:1911.06883 (cross-list from hep-ph) [pdf, other]
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Title: History of Neutrino Magnetic MomentAuthors: Jihn E. KimComments: 7 pages of LaTeX file with 3 figuresSubjects: High Energy Physics - Phenomenology (hep-ph); Solar and Stellar Astrophysics (astro-ph.SR)
In this historic Lomonosov conference on the occasion of 150 year anniversary of the Mendeleev's periodic table, I present the history of neutrino magnetic moment. It was first thought by Wolfgang Pauli and its magnitude was calculated during the gauge theory era.
- [57] arXiv:1911.06908 (cross-list from gr-qc) [pdf, ps, other]
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Title: Topological neutron stars in tensor-multi-scalar theories of gravityComments: 6 pages, 6 figuresSubjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE)
In the present paper we demonstrate that there exists a new type of neutron stars in the tensor-multi-scalar theories of gravity. We call this new type of neutron stars topological neutron stars. In addition to the standard characteristics of the usual neutron stars the topological neutron stars are also characterized by a topological charge. We numerical construct explicit examples of topological neutron stars in tensor-multi-scalar theories whose target space is $\mathbb{S}^3$. Besides the topological charge the topological neutron stars also exhibit other attractive features which can place them among the realistic compact objects that could exist in Nature. For example they possess zero scalar charge and thus evades the strong binary pulsar constraints on the dipole scalar radiation.
- [58] arXiv:1911.07082 (cross-list from hep-ph) [pdf, other]
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Title: Particle physics model of curvaton inflation in a stable universeSubjects: High Energy Physics - Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Theory (hep-th)
We investigate a particle physics model for cosmic inflation based on the following assumptions: (i) there are at least two complex scalar fields; (ii) the scalar potential is bounded from below and remains perturbative up to the Planck scale; (iii) we assume slow-roll inflation with maximally correlated adiabatic and entropy fluctuations 50--60 e-folds before the end of inflation. The energy scale of the inflation is set automatically by the model. Assuming also at least one massive right handed neutrino, we explore the allowed parameter space of the scalar potential as a function of the Yukawa coupling of this neutrino.
- [59] arXiv:1911.07091 (cross-list from gr-qc) [pdf, other]
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Title: Studying strong phase transitions in neutron stars with gravitational wavesComments: 21 pages, 12 figures, 3 tablesSubjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
The composition of neutron stars at the extreme densities reached in their cores is currently unknown. Besides nuclear matter of normal neutrons and protons, the cores of neutron stars might harbor exotic matter such as deconfined quarks. In this paper we study strong hadron-quark phase transitions in the context of gravitational wave observations of inspiraling neutron stars. We consider upcoming detections of neutron star coalescences and model the neutron star equations of state with phase transitions through the Constant-Speed-of-Sound parametrization. We use the fact that neutron star binaries with one or more hadron-quark hybrid stars can exhibit qualitatively different tidal properties than binaries with hadronic stars of the same mass, and hierarchically model the masses and tidal properties of simulated populations of binary neutron star inspiral signals. We explore the parameter space of phase transitions and discuss under which conditions future observations of binary neutron star inspirals can identify this effect and constrain its properties, in particular the threshold density at which the transition happens and the strength of the transition. We find that if the detected population of binary neutron stars contains both hadronic and hybrid stars, the onset mass and strength of a sufficiently strong phase transition can be constrained with 50-100 detections. If the detected neutron stars are exclusively hadronic or hybrid, then it is possible to place lower or upper limits on the transition density and strength.
- [60] arXiv:1911.07207 (cross-list from physics.space-ph) [pdf]
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Title: Expansion of Solar Coronal Hot Electrons in an Inhomogeneous Magnetic Field: 1-D PIC SimulationComments: 17pages, 4 figures, accepted by ApJSubjects: Space Physics (physics.space-ph); Solar and Stellar Astrophysics (astro-ph.SR); Plasma Physics (physics.plasm-ph)
The expansion of hot electrons in flaring magnetic loops is crucial to understanding the dynamics of solar flares. In this paper we investigate, for the first time, the transport of hot electrons in a magnetic mirror field based on a 1-D particle-in-cell (PIC) simulation. The hot electrons with small pitch angle transport into the cold plasma, which leads to the generation of Langmuir waves in the cold plasma and ion acoustic waves in the hot plasma. The large pitch angle electrons can be confined by the magnetic mirror, resulting in the different evolution time scale between electron parallel and perpendicular temperature. This will cause the formation of electron temperature anisotropy, which can generate the whistler waves near the interface between hot electrons and cold electrons. The whistler waves can scatter the large pitch angle electrons to smaller value through the cyclotron resonance, leading to electrons escaping from the hot region. These results indicate that the whistler waves may play an important role in the transport of electrons in flaring magnetic loops. The findings from this study provide some new insights to understand the electron dynamics of solar flares.
- [61] arXiv:1911.07329 (cross-list from gr-qc) [pdf, ps, other]
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Title: Ghost-free non-local $F(R)$ Gravity CosmologySubjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Theory (hep-th)
In this work we shall study ghost-free non-local $F(R)$ gravity models. Firstly we shall demonstrate how the ghost degrees of freedom may occur in the non-local $F(R)$ gravity models, and accordingly we shall modify appropriately the gravitational action of non-local $F(R)$ gravity models in order to eliminate the ghosts. Also we shall investigate how the (anti-)de Sitter and the Minkowski spacetime cosmological solutions may arise in the theory, and we investigate when these solutions are stable. Moreover, we shall examine the inflationary phenomenology of the Jordan frame ghost-free non-local $F(R)$ gravity. We shall study two $F(R)$ gravity models, the power law $F(R)$ gravity model $\sim R^n$ with $1<n<2$, $n\neq 2$ and the $R^2$ model, assuming that the slow-roll condition holds true for the Hubble rate during the inflationary era $\dot{H}\ll H^2$ and that the general constant-roll condition $\ddot{\phi}=3\beta H\dot{\phi}$ holds true for the evolution of the scalar field, which includes the slow-roll case for $\beta=0$. As we shall demonstrate, the power-law non-local $F(R)$ gravity case can produce a viable inflationary era, compatible with observations, in the constant-roll case, unlike for the $R^2$ model. It is conceivable that the results are model dependent, as in the ordinary vacuum $F(R)$ gravity.
- [62] arXiv:1911.07530 (cross-list from hep-ph) [pdf, other]
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Title: The Sun at TeV energies: gammas, neutrons, neutrinos and a cosmic ray shadowComments: 8 pagesSubjects: High Energy Physics - Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE)
High energy cosmic rays reach the surface of the Sun and start showers with thousands of secondary particles. Most of them will be absorbed by the Sun, but a fraction of the neutral ones will escape and reach the Earth. Here we incorporate a new ingredient that is essential to understand the flux of these solar particles: the cosmic ray shadow of the Sun. We use Liouville's theorem to argue that the only effect of the solar magnetic field on the isotropic cosmic ray flux is to interrupt some of the trajectories that were aiming to the Earth and create a shadow. This shadow reveals the average solar depth crossed by cosmic rays of a given rigidity. The absorbed cosmic ray flux is then processed in the thin solar surface and, assuming that the emission of neutral particles by low-energy charged particles is isotropic, we obtain (i) a flux of gammas that seems consistent with Fermi-LAT observations, (ii) a flux of neutrons (100-300 neutrons per year and m^2) produced basically in the spallation of primary He nuclei, and (iii) a neutrino flux that is above the atmospheric neutrino background at energies above 0.1-0.6 TeV (depending on the zenith inclination). More precise measurements of the cosmic ray shadow and of the solar gamma flux, together with the possible discovery of the neutron and neutrino signals, would provide valuable information about the magnetic field, the cycle, and the interior of the Sun.
- [63] arXiv:1911.07593 (cross-list from gr-qc) [pdf, other]
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Title: Quasi-Normal Modes of Hairy Scalar Tensor Black Holes: Odd ParityAuthors: Oliver J. TattersallComments: 7 pages, submitted to PRDSubjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
The odd parity gravitational Quasi-Normal Mode spectrum of black holes with non-trivial scalar hair in Horndeski gravity is investigated. We study `almost' Schwarzschild black holes such that any modifications to the spacetime geometry (including the scalar field profile) are treated perturbatively. A modified Regge-Wheeler style equation for the odd parity gravitational degree of freedom is presented to quadratic order in the scalar hair and spacetime modifications, and a parameterisation of the modified Quasi-Normal Mode spectrum is calculated. In addition, statistical error estimates for the new hairy parameters of the black hole and scalar field are given.
- [64] arXiv:1911.07618 (cross-list from hep-th) [pdf, other]
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Title: Slepian models for Gaussian Random LandscapesComments: 51 pages, 14 figuresSubjects: High Energy Physics - Theory (hep-th); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
Phenomenologically interesting scalar potentials are highly atypical in generic random landscapes. We develop the mathematical techniques to generate constrained random potentials, i.e. Slepian models, which can globally represent low-probability realizations of the landscape. We give analytical as well as numerical methods to construct these Slepian models for constrained realizations of a full Gaussian random field around critical as well as inflection points. We use these techniques to numerically generate in an efficient way a large number of minima at arbitrary heights of the potential and calculate their non-perturbative decay rate. Furthermore, we also illustrate how to use these methods by obtaining statistical information about the distribution of observables in an inflationary inflection point constructed within these models.
- [65] arXiv:1911.07645 (cross-list from gr-qc) [pdf, other]
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Title: Influence of weak electromagnetic fields on charged particle ISCOsSubjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE)
Astrophysical black holes are often embedded into electromagnetic fields, that can usually be treated as test fields not influencing the spacetime geometry. Here we analyse the innermost stable circular orbit (ISCO) of charged particles moving around a Schwarzschild black hole in the presence of a radial electric test field and an asymptotically uniform magnetic test field. We discuss the structure of the in general four ISCO solutions for different magnitudes of the electric and the magnetic field's strength. In particular, we find that the nonexistence of stable circular orbits of particles with equal sign of charge as the black hole for sufficiently strong electric fields can be canceled by a sufficiently strong magnetic field. In this situation, we find that ISCOs made of static particles will emerge.
Replacements for Tue, 19 Nov 19
- [66] arXiv:1701.08450 (replaced) [src]
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Title: 3D Global MHD Modeling of Solar Subsurface ConvectionComments: The wrong article was accidentally submitted, it will be resubmitted in its full form along with a link to the published article in ApJ, so that it can be more easily linked to NASA ADSSubjects: Solar and Stellar Astrophysics (astro-ph.SR)
- [67] arXiv:1706.03119 (replaced) [pdf]
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Title: Upper Limits on Gravitational Waves from Scorpius X-1 from a Model-Based Cross-Correlation Search in Advanced LIGO DataAuthors: The LIGO Scientific Collaboration, the Virgo Collaboration: B. P. Abbott, R. Abbott, T. D. Abbott, F. Acernese, K. Ackley, C. Adams, T. Adams, P. Addesso, R. X. Adhikari, V. B. Adya, C. Affeldt, M. Afrough, B. Agarwal, M. Agathos, K. Agatsuma, N. Aggarwal, O. D. Aguiar, L. Aiello, A. Ain, P. Ajith, B. Allen, G. Allen, A. Allocca, P. A. Altin, A. Amato, A. Ananyeva, S. B. Anderson, W. G. Anderson, S. Antier, S. Appert, K. Arai, M. C. Araya, J. S. Areeda, N. Arnaud, K. G. Arun, S. Ascenzi, G. Ashton, M. Ast, S. M. Aston, P. Astone, P. Aufmuth, C. Aulbert, K. AultONeal, A. Avila-Alvarez, S. Babak, P. Bacon, M. K. M. Bader, S. Bae, P. T. Baker, F. Baldaccini, G. Ballardin, S. W. Ballmer, S. Banagiri, J. C. Barayoga, S. E. Barclay, B. C. Barish, D. Barker, F. Barone, B. Barr, L. Barsotti, M. Barsuglia, et al. (986 additional authors not shown)Comments: 19 pages, 8 figures. Formatted with AASTeX 6.1. Published in The Astrophysical JournalJournal-ref: The Astrophysical Journal, 847:47 (14pp), 2017 September 20Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc)
- [68] arXiv:1706.09734 (replaced) [pdf, other]
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Title: Probing homogeneity with standard candlesComments: version accepted by JCAPSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
- [69] arXiv:1712.02637 (replaced) [pdf, ps, other]
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Title: Can Quantum Particles Cross a Horizon?Authors: Merab GogberashviliComments: The version published in Int. J. Theor. PhysJournal-ref: International Journal of Theoretical Physics, 58(11), 3711-3725 (2019)Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Theory (hep-th)
- [70] arXiv:1810.02764 (replaced) [pdf, ps, other]
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Title: A Fermi Gamma-ray Burst Monitor Search for Electromagnetic Signals Coincident with Gravitational-Wave Candidates in Advanced LIGO's First Observing RunAuthors: The Fermi Gamma-ray Burst Monitor Team, The LIGO Scientific Collaboration, the Virgo Collaboration: E. Burns, A. Goldstein, C. M. Hui, L. Blackburn, M. S. Briggs, V. Connaughton, R. Hamburg, D. Kocevski, P. Veres, C. A. Wilson-Hodge, E. Bissaldi, W. H. Cleveland, M. M. Giles, B. Mailyan, C. A. Meegan, W. A. Paciesas, S. Poolakkil, R. D. Preece, J. L. Racusin, O. J. Roberts, A. von Kienlin, B. P. Abbott, R. Abbott, T. D. Abbott, F. Acernese, K. Ackley, C. Adams, T. Adams, P. Addesso, R. X. Adhikari, V. B. Adya, C. Affeldt, B. Agarwal, M. Agathos, K. Agatsuma, N. Aggarwal, O. D. Aguiar, L. Aiello, A. Ain, P. Ajith, B. Allen, G. Allen, A. Allocca, M. A. Aloy, P. A. Altin, A. Amato, A. Ananyeva, S. B. Anderson, W. G. Anderson, S. V. Angelova, S. Antier, S. Appert, K. Arai, M. C. Araya, J. S. Areeda, et al. (1105 additional authors not shown)Comments: Published in ApJSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
- [71] arXiv:1810.13270 (replaced) [pdf, other]
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Title: Statistical analysis of binary stars from the Gaia catalogue DR2Comments: 20 pages, 16 figures, the new version is accepted by the Astronomical JournalSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Solar and Stellar Astrophysics (astro-ph.SR); High Energy Physics - Phenomenology (hep-ph)
- [72] arXiv:1811.11192 (replaced) [pdf, other]
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Title: Cosmic Dawn II (CoDa II): a new radiation-hydrodynamics simulation of the self-consistent coupling of galaxy formation and reionizationAuthors: Pierre Ocvirk, Dominique Aubert, Jenny G. Sorce, Paul R. Shapiro, Nicolas Deparis, Taha Dawoodbhoy, Joseph Lewis, Romain Teyssier, Gustavo Yepes, Stefan Gottlöber, Kyungjin Ahn, Ilian T. Iliev, Yehuda HoffmanComments: 20 pages, 11 figures, submitted to MNRASSubjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
- [73] arXiv:1812.02745 (replaced) [pdf, other]
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Title: SDSS-IV MaStar -- A Large and Comprehensive Empirical Stellar Spectral Library: First ReleaseAuthors: Renbin Yan, Yanping Chen, Daniel Lazarz, Dmitry Bizyaev, Claudia Maraston, Guy S. Stringfellow, Kyle McCarthy, Sofia Meneses-Goytia, David R. Law, Daniel Thomas, Jesus Falcon Barroso, José R. Sánchez-Gallego, Edward Schlafly, Zheng Zheng, Maria Argudo-Fernández, Rachael L. Beaton, Timothy C. Beers, Matthew Bershady, Michael R. Blanton, Joel Brownstein, Kevin Bundy, Kenneth C. Chambers, Brian Cherinka, Nathan De Lee, Niv Drory, Lluís Galbany, Jon Holtzman, Julie Imig, Nick Kaiser, Karen Kinemuchi, Chao Liu, A-Li Luo, Eugene Magnier, Steven Majewski, Preethi Nair, Audrey Oravetz, Daniel Oravetz, Kaike Pan, Jennifer Sobeck, Keivan Stassun, Michael Talbot, Christy Tremonti, Christopher Waters, Anne-Marie Weijmans, Ronald Wilhelm, Gail Zasowski, Gang Zhao, Yong-Heng ZhaoComments: 36 pages, 15 figures, 8 tables, including 2 large electronic tables. Published in ApJJournal-ref: ApJ, 883, 175 (2019)Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
- [74] arXiv:1812.06076 (replaced) [pdf, other]
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Title: KiDS+VIKING-450: Cosmic shear tomography with optical+infrared dataAuthors: H. Hildebrandt, F. Köhlinger, J. L. van den Busch, B. Joachimi, C. Heymans, A. Kannawadi, A. H. Wright, M. Asgari, C. Blake, H. Hoekstra, S. Joudaki, K. Kuijken, L. Miller, C. B. Morrison, T. Tröster, A. Amon, M. Archidiacono, S. Brieden, A. Choi, J. T. A. de Jong, T. Erben, B. Giblin, A. Mead, J. A. Peacock, M. Radovich, P. Schneider, C. Sifón, M. TewesComments: 31 pages, 14 figures, accepted for publication by A&A; data products available at this http URLSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
- [75] arXiv:1901.11136 (replaced) [pdf, ps, other]
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Title: Pulsational Pair-instability Supernovae. I. Pre-collapse Evolution and Pulsational Mass EjectionComments: 33 pages, 57 figures, submitted 2019 January 29; revised 2019 October 16; accepted 2019 October 20Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)
- [76] arXiv:1902.05792 (replaced) [pdf, other]
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Title: Neutrinos below 100 TeV from the southern sky employing refined veto techniques to IceCube dataAuthors: IceCube Collaboration: M. G. Aartsen, M. Ackermann, J. Adams, J. A. Aguilar, M. Ahlers, M. Ahrens, C. Alispach, D. Altmann, K. Andeen, T. Anderson, I. Ansseau, G. Anton, C. Argüelles, J. Auffenberg, S. Axani, P. Backes, H. Bagherpour, X. Bai, A. Barbano, S. W. Barwick, V. Baum, R. Bay, J. J. Beatty, K.-H. Becker, J. Becker Tjus, S. BenZvi, D. Berley, E. Bernardini, D. Z. Besson, G. Binder, D. Bindig, E. Blaufuss, S. Blot, C. Bohm, M. Börner, S. Böser, O. Botner, E. Bourbeau, J. Bourbeau, F. Bradascio, J. Braun, H.-P. Bretz, S. Bron, J. Brostean-Kaiser, A. Burgman, R. S. Busse, T. Carver, C. Chen, E. Cheung, D. Chirkin, K. Clark, L. Classen, G. H. Collin, J. M. Conrad, P. Coppin, P. Correa, D. F. Cowen, R. Cross, P. Dave, J. P. A. M. de André, C. De Clercq, J. J. DeLaunay, et al. (272 additional authors not shown)Comments: 19 pages, 17 figures, 2 tablesJournal-ref: Astroparticle Physics, Volume 116 (2020), Pages 102392Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Experiment (hep-ex)
- [77] arXiv:1902.07200 (replaced) [pdf, other]
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Title: Isotropic charged cosmologies in infrared-modified electrodynamicsComments: 10 pages, 6 figuresJournal-ref: Phys. Rev. D 100, 083532 (2019)Subjects: High Energy Physics - Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc)
- [78] arXiv:1902.10795 (replaced) [pdf]
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Title: Impact Craters on Pluto and Charon Indicate a Deficit of Small Kuiper Belt ObjectsAuthors: K. N. Singer, W. B. McKinnon, B. Gladman, S. Greenstreet, E. B. Bierhaus, S. A. Stern, A. H. Parker, S. J. Robbins, P. M. Schenk, W. M. Grundy, V. J. Bray, R. A. Beyer, R. P. Binzel, H. A. Weaver, L. A. Young, J. R. Spencer, J. J. Kavelaars, J. M. Moore, A. M. Zangari, C. B. Olkin, T. R. Lauer, C. M. Lisse, K. Ennico (New Horizons Geology, Geophysics and Imaging Science Theme Team, New Horizons Surface Composition Science)Journal-ref: 1 March 2019, Science 363, 955 (2019)Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
- [79] arXiv:1904.04037 (replaced) [pdf, other]
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Title: Stellar 3-D kinematics in the Draco dwarf spheroidal galaxyAuthors: Davide Massari, Amina Helmi, Alessio Mucciarelli, Laura V. Sales, Lorenzo Spina, Eline TolstoyComments: 12 pages, 15 figures, 3 tables. Accepted for publication by A&ASubjects: Astrophysics of Galaxies (astro-ph.GA)
- [80] arXiv:1904.11923 (replaced) [pdf, other]
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Title: Intensity mapping with neutral hydrogen and the Hidden Valley simulationsComments: 36 pages, 21 figures. Simulations available at this http URL Minor changes in HI normalization described in footnote of section 4Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
- [81] arXiv:1904.12789 (replaced) [pdf, other]
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Title: Constraining a nonminimally coupled curvature-matter gravity model with ocean experimentsComments: 17 pages, 5 figuresJournal-ref: Phys. Rev. D 100, 042002 (2019)Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
- [82] arXiv:1904.13261 (replaced) [pdf, other]
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Title: Stochastic gravitational wave background from accreting primordial black hole binaries during early inspiral stageComments: 11 pages and 8 figuresJournal-ref: Phys. Rev. D 100, 103514 ; 2019Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc)
- [83] arXiv:1904.13265 (replaced) [pdf, other]
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Title: Predicting CMB dust foreground using galactic 21 cm dataComments: 16 pages, 7 figures; matches JCAP accepted versionSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
- [84] arXiv:1905.02727 (replaced) [pdf, other]
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Title: Constraining the Self-Interacting Neutrino Interpretation of the Hubble TensionComments: 11 pages, 1 figure, 4 appendices. Version 2 matches published versionJournal-ref: Phys. Rev. Lett. 123, 191102 (2019)Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Experiment (hep-ex); High Energy Physics - Phenomenology (hep-ph)
- [85] arXiv:1905.05116 (replaced) [pdf, other]
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Title: Petabytes to ScienceAuthors: Amanda E. Bauer, Eric C. Bellm, Adam S. Bolton, Surajit Chaudhuri, A.J. Connolly, Kelle L. Cruz, Vandana Desai, Alex Drlica-Wagner, Frossie Economou, Niall Gaffney, J. Kavelaars, J. Kinney, Ting S. Li, B. Lundgren, R. Margutti, G. Narayan, B. Nord, Dara J. Norman, W. O'Mullane, S. Padhi, J. E. G. Peek, C. Schafer, Megan E. Schwamb, Arfon M. Smith, Erik J. Tollerud, Anne-Marie Weijmans, Alexander S. SzalayComments: 70 pages 2 figures - this contains a few fixesSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
- [86] arXiv:1907.02111 (replaced) [pdf, other]
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Title: J-PLUS: Synthetic galaxy catalogues with emission lines for photometric surveysAuthors: David Izquierdo-Villalba, Raul E. Angulo, Alvaro Orsi, Guillaume Hurier, Gonzalo Vilella-Rojo, Silvia Bonoli, Carlos López-Sanjuan, Jailson Alcaniz, Javier Cenarro, David Cristóbal-Hornillos, Renato Dupke, Alessandro Ederoclite, Carlos Hernández-Monteagudo, Antonio Marín-Franch, Mariano Moles, Claudia Mendes de Oliveira, Laerte Sodré Jr., Jesús Varela, Héctor Vázquez RamióComments: Published in A&A; Mock catalogue available at this https URLJournal-ref: A&A 631, A82 (2019)Subjects: Astrophysics of Galaxies (astro-ph.GA)
- [87] arXiv:1907.03867 (replaced) [pdf, other]
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Title: SAGE: A Proposal for a Space Atomic Gravity ExplorerAuthors: G. M. Tino, A. Bassi, G. Bianco, K. Bongs, P. Bouyer, L. Cacciapuoti, S. Capozziello, X. Chen, M. L. Chiofalo, A. Derevianko, W. Ertmer, N. Gaaloul, P. Gill, P. W. Graham, J. M. Hogan, L. Iess, M. A. Kasevich, H. Katori, C. Klempt, X. Lu, L.-S. Ma, H. Müller, N. R. Newbury, C. Oates, A. Peters, N. Poli, E. Rasel, G. Rosi, A. Roura, C. Salomon, S. Schiller, W. Schleich, D. Schlippert, F. Schreck, C. Schubert, F. Sorrentino, U. Sterr, J. W. Thomsen, G. Vallone, F. Vetrano, P. Villoresi, W. von Klitzing, D. Wilkowski, P. Wolf, J. Ye, N. Yu, M. S. ZhanComments: Published in Eur. Phys. J. D 73 (2019) 228 in the Topical Issue Quantum Technologies for Gravitational Physics, Guest editors Tanja Mehlstaubler, Yanbei Chen, Guglielmo M. Tino and Hsien-Chi YehSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); General Relativity and Quantum Cosmology (gr-qc); Atomic Physics (physics.atom-ph); Quantum Physics (quant-ph)
- [88] arXiv:1907.04342 (replaced) [pdf, other]
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Title: The 21cm bispectrum during reionization: a tracer of the ionization topologyAuthors: Anne Hutter, Catherine A. Watkinson, Jacob Seiler, Pratika Dayal, Manodeep Sinha, Darren J. CrotonComments: 16 pages, 7 figures. Accepted for publication in MNRASSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA)
- [89] arXiv:1907.05237 (replaced) [pdf, other]
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Title: Dissecting the growth of the power spectrum for primordial black holesComments: 7 pages, 3 figures. Typos corrected and references added. Matches version to appear in PRDSubjects: 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)
- [90] arXiv:1907.06648 (replaced) [pdf, other]
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Title: SOFIA/HAWC+ traces the magnetic fields in NGC 1068Authors: E. Lopez-Rodriguez, C. D. Dowell, T. J. Jones, D. A. Harper, M. Berthoud, D. Chuss, D. A. Dale, J. A. Guerra, R. T. Hamilton, L. W. Looney, J. M. Michail, R. Nikutta, G. Novak, F. P. Santos, K. Sheth, J. Siah, J. Staguhn, I. W. Stephens, K. Tassis, C. Q. Trinh, D. Ward-Thompson, M. Werner, E. J. Wollack, E. Zweibel (HAWC+ Science Team)Comments: 13 pages, 7 figures, Accepted for publication by ApJSubjects: Astrophysics of Galaxies (astro-ph.GA)
- [91] arXiv:1908.02542 (replaced) [pdf, other]
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Title: Probing the era of reheating for reconstructed inflationary potential in the RS II braneworldComments: 16 pages, 9 figuresSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph)
- [92] arXiv:1908.07987 (replaced) [pdf]
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Title: Variability of Ha emission in young stellar objects in the cluster IC 348Comments: 21 pages, 9 figures, 5 tablesSubjects: Solar and Stellar Astrophysics (astro-ph.SR)
- [93] arXiv:1909.00849 (replaced) [pdf, other]
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Title: The Galactic Halo Contribution to the Dispersion Measure of Extragalactic Fast Radio BurstsComments: 11 pages, 9 figures, 1 table, 2 hot gas halo components, accepted for publication in ApJ; v2Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA)
- [94] arXiv:1909.01371 (replaced) [pdf, other]
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Title: Impact of progenitor's rotation and compactness on the mass of black holesAuthors: Michela Mapelli, Mario Spera, Enrico Montanari, Marco Limongi, Alessandro Chieffi, Nicola Giacobbo, Alessandro Bressan, Yann BouffanaisComments: 15 pages, 5 figures, 1 table; ApJ, in pressSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)
- [95] arXiv:1909.05225 (replaced) [pdf, other]
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Title: Dynamic fast flavor oscillation waves in dense neutrino gasesComments: 7 pages, 5 figures. Minor changes for clarificationJournal-ref: Phys. Lett. B, 800, 135088 (2020)Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
- [96] arXiv:1909.05867 (replaced) [pdf, other]
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Title: Jet Propagation in Neutron Star Mergers and GW170817Comments: 28 pages, 10 figures, and 2 tablesSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
- [97] arXiv:1909.11101 (replaced) [pdf, ps, other]
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Title: Mid-IR Variability and Dust Reverberation Mapping of Low-$z$ Quasars. I. Data, Methods and Basic ResultsComments: ApJ accepted (35 pages, 21 figures), revised to match the published paperJournal-ref: ApJ, 886, 33 (2019)Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
- [98] arXiv:1909.11106 (replaced) [pdf, other]
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Title: Trans-Planckian Censorship and Inflationary CosmologyComments: 6 pages, 1 figureSubjects: High Energy Physics - Theory (hep-th); Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph)
- [99] arXiv:1910.04604 (replaced) [pdf, other]
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Title: The most luminous blue quasars at $3.0<z<3.3$. I. A tale of two X-ray populationsAuthors: E. Nardini, E. Lusso, G. Risaliti, S. Bisogni, F. Civano, M. Elvis, G. Fabbiano, R. Gilli, A. Marconi, F. Salvestrini, C. VignaliComments: Version accepted for publication in Astronomy & Astrophysics (13+2 pages, 10+1 figures, 3 tables)Subjects: Astrophysics of Galaxies (astro-ph.GA)
- [100] arXiv:1910.05029 (replaced) [pdf]
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Title: Characterization of material around the centaur (2060) Chiron from a visible and near-infrared stellar occultation in 2011Authors: A.A. Sickafoose, A.S. Bosh, J.P. Emery, M.J. Person, C.A. Zuluaga, M. Womack, J.D. Ruprecht, F.B. Bianco, A.M. ZangariComments: Submitted to MNRAS: 13 pages, 10 figures, 3 tablesSubjects: Earth and Planetary Astrophysics (astro-ph.EP)
- [101] arXiv:1910.05414 (replaced) [pdf, other]
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Title: Circumbinary exoplanets and brown dwarfs with the Laser Interferometer Space AntennaComments: 16 pages, 8 figures, A&A in pressSubjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM); Solar and Stellar Astrophysics (astro-ph.SR); General Relativity and Quantum Cosmology (gr-qc)
- [102] arXiv:1910.11389 (replaced) [pdf, other]
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Title: Orbital Decay in a 20 Minute Orbital Period Detached Binary with a Hydrogen Poor Low Mass White DwarfAuthors: Kevin B Burdge, Jim Fuller, E. Sterl Phinney, Jan van Roestel, Antonio Claret, Elena Cukanovaite, Nicola Pietro Gentile Fusillo, Michael W. Coughlin, David L. Kaplan, Thomas Kupfer, Pier-Emmanuel Tremblay, Richard G. Dekany, Dmitry A. Duev, Michael Feeney, Reed Riddle, S. R. Kulkarni, Thomas A. PrinceComments: 12 pages, 9 figures, 3 tables. Published online by the Astrophysical Journal Letters November 15, 2019Journal-ref: ApJL 886 L12 (2019)Subjects: Solar and Stellar Astrophysics (astro-ph.SR); High Energy Astrophysical Phenomena (astro-ph.HE)
- [103] arXiv:1910.13612 (replaced) [pdf]
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Title: Orbits and resonances of the regular moons of NeptuneAuthors: Marina Brozović, Mark R. Showalter, Robert A. Jacobson, Robert S. French, Jack J. Lissauer, Imke de PaterComments: Accepted in Icarus, October 1, 2019Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
- [104] arXiv:1911.03474 (replaced) [pdf, other]
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Title: Estimating weak lensing convergence correlation of Type-Ia supernovae from 5-year SNLS data by internal error estimate techniqueComments: A manuscript using the same data but with a preliminary level of analysis was submitted to arXiv on February, 2018 (arxiv:1802.09014, Now withdrawn). However, we have done a thorough modification to that version with a completely new method of analysis using updated technique leading to several new findings and request the arXiv admin to consider it as a fresh submissionSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc)
- [105] arXiv:1911.04809 (replaced) [pdf, other]
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Title: Slicing the cool circumgalactic medium along the major-axis of a star-forming galaxy at $z = 0.7$Authors: S. Lopez, N. Tejos, L. F. Barrientos, C. Ledoux, K. Sharon, A. Katsianis, M. K. Florian, E. Rivera-Thorsen, M. B. Bayliss, H. Dahle, A. Fernandez-Figueroa, M. D. Gladders, M. Gronke, M. Hamel, I. Pessa, J. R. RigbyComments: Accepted for publication in MNRASSubjects: Astrophysics of Galaxies (astro-ph.GA)
- [106] arXiv:1911.05311 (replaced) [pdf, ps, other]
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Title: Gravitational lensing signature of matter distribution around Schwarzschild black holeComments: 33 pages, 7 figures, minor changes, references updatedSubjects: General Relativity and Quantum Cosmology (gr-qc); Astrophysics of Galaxies (astro-ph.GA); High Energy Physics - Theory (hep-th)
- [107] arXiv:1911.05453 (replaced) [pdf, ps, other]
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Title: Comment on "The Flyby Anomaly and the Gravitational-Magnetic Field Induced Frame-Dragging Effect around the Earth"Authors: V. GuruprasadComments: To be submittedSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
- [108] arXiv:1911.05753 (replaced) [pdf, other]
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Title: The Cloud Factory I: Generating resolved filamentary molecular clouds from galactic-scale forcesAuthors: Rowan J. Smith, Robin G. Treß, Mattia C. Sormani, Simon C.O. Glover, Ralf S. Klessen, Paul C. Clark, Andrés F. Izquierdo, Ana Duarte Cabral, Catherine ZuckerComments: 20 pages, 15 figures, submitted to MNRASSubjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
- [109] arXiv:1911.05983 (replaced) [pdf, other]
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Title: f(R)-gravity models constrained with cosmological dataComments: 15 pages, 13 figures, and 45 references. This is a re-submission [v2] with updated references and fixed typing errors. This work is based on Renier Hough's Masters dissertation resultsSubjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
- [110] arXiv:1911.06271 (replaced) [pdf, ps, other]
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Title: Sublimation of Water Ice from a Population of Large, Long-Lasting Grains Near the Nucleus of 2I/Borisov?Authors: Zdenek SekaninaComments: 7 pages, 3 figures, 1 tableSubjects: Earth and Planetary Astrophysics (astro-ph.EP)
- [111] arXiv:1911.06806 (replaced) [pdf, other]
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Title: Anomalous peculiar motions of high-mass young stars in the Scutum spiral armComments: 27 pages, 52 figures, 4 tables, accepted for publication in A&ASubjects: Astrophysics of Galaxies (astro-ph.GA)
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