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New submissions for Fri, 13 Dec 19

[1]  arXiv:1912.05542 [pdf, other]

Title: Realistic Models for Filling and Abundance Discrepancy Factors in Photoionised Nebulae

Authors: Brandon M. Bergerud, Steven R. Spangler, Kara M. Beauchamp

Comments: 13 pages, 12 figures

Subjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)

When comparing nebular electron densities derived from collisionally excited lines (CELs) to those estimated using the emission measure, significant discrepancies are common. The standard solution is to view nebulae as aggregates of dense regions of constant density in an otherwise empty void. This porosity is parametrized by a filling factor $f<1$. Similarly, abundance and temperature discrepancies between optical recombination lines (ORLs) and CELs are often explained by invoking a dual delta distribution of a dense, cool, metal-rich component immersed in a diffuse, warm, metal-poor plasma. In this paper, we examine the possibility that the observational diagnostics that lead to such discrepancies can be produced by a realistic distribution of density and temperature fluctuations, such as might arise in plasma turbulence. We produce simulated nebulae with density and temperature fluctuations described by various probability distribution functions (pdfs). Standard astronomical diagnostics are applied to these simulated observations to derive estimates of nebular densities, temperatures, and abundances. Our results show that for plausible density pdfs the simulated observations lead to filling factors in the observed range. None of our simulations satisfactorily reproduce the abundance discrepancy factors (ADFs) in planetary nebulae, although there is possible consistency with \ion{H}{ii} regions. Compared to the case of density-only and temperature-only fluctuations, a positive correlation between density and temperature reduces the filling factor and ADF (from optical CELs), whereas a negative correlation increases both, eventually causing the filling factor to exceed unity. This result suggests that real observations can provide constraints on the thermodynamics of small scale fluctuations.

[2]  arXiv:1912.05545 [pdf, other]

Title: Runaway Coalescence of Pre-Common-Envelope Stellar Binaries

Authors: Morgan MacLeod, Abraham Loeb

Comments: Submitted to AAS Journals, we welcome comments. Associated software available here: this https URL and here: this https URL

Subjects: Solar and Stellar Astrophysics (astro-ph.SR)

We study the process of runaway, unstable Roche lobe overflow in coalescing binary systems and its dependence on the properties of the binary involved. We create three-dimensional hydrodynamic models of binary coalescences, and follow them through a phase of increasing Roche lobe overflow until the accretor is engulfed by the donor at the onset of a common envelope phase. In these models, we vary binary properties of mass ratio, donor structure and spin, and equation of state through the gas adiabatic index. We compare the numerical results to semi-analytic models of binary orbit evolution based on mass and angular momentum exchange between two point masses. Using our hydrodynamic simulations, we measure the key parameters: the donor mass loss rate and the angular momentum exchanged per unit mass loss from the donor. Using these calibrations, the semi-analytic model closely reproduces the escalating mass loss and runaway orbital decay observed in the hydrodynamic models. The semi-analytic model accurately reproduces the major differences in orbit evolution that arise with varying mass ratio and donor structure. We encapsulate the semi-analytic model in a publicly-released python package RLOF. We apply this model to the observed period decay and subsequent merger of the binary V1309 Sco, and find that it can simultaneously reproduce the observed orbital decay and time of outburst. We further demonstrate that there is a relationship between period derivative and second derivative that can be a useful metric for evaluating candidate merging binaries.

[3]  arXiv:1912.05548 [pdf, other]

Title: Molecular Gas Inflows and Outflows in Ultraluminous Infrared Galaxies at $z\sim0.2$ and one QSO at $z=6.1$

Authors: R. Herrera-Camus, E. Sturm, J. Graciá-Carpio, S. Veilleux, T. Shimizu, D. Lutz, M. Stone, E. González-Alfonso, R. Davies, J. Fischer, R. Genzel, R. Maiolino, A. Sternberg, L. Tacconi, A. Verma

Comments: 9 pages, 6 figures, accepted for publication in A&A as a Letter to the Editor

Subjects: Astrophysics of Galaxies (astro-ph.GA)

Aims. We aim to search and characterize inflows and outflows of molecular gas in four ultraluminous infrared galaxies (ULIRGs) at $z\sim0.2-0.3$ and one distant QSO at $z=6.13$.
Methods. We use Herschel PACS and ALMA Band 7 observations of the hydroxyl molecule (OH) line at rest-frame wavelength 119 $\mu$m which in absorption can provide unambiguous evidence for inflows or outflows of molecular gas in nuclear regions of galaxies. Our study contributes to double the number of OH observations of luminous systems at $z\sim0.2-0.3$, and push the search for molecular outflows based on the OH transition to $z\sim6$.
Results. We detect OH high-velocity absorption wings in three of the four ULIRGs. In two cases, IRAS F20036-1547 and IRAS F13352+6402, the blueshifted absorption profiles indicate the presence of powerful and fast molecular gas outflows. Consistent with an inside-out quenching scenario, these outflows are depleting the central reservoir of molecular gas at a similar rate than the intense star formation activity. In the case of the starburst-dominated system IRAS 10091+4704, we detect an inverted P-Cygni profile that is unique among ULIRGs and indicates the presence of a fast ($\sim400$ km s$^{-1}$) inflow of molecular gas at a rate of $\sim100~M_{\odot}~{\rm yr}^{-1}$ towards the central region. Finally, we tentatively detect ($\sim3\sigma$) the OH doublet in absorption in the $z=6.13$ QSO ULAS J131911+095051. The OH feature is blueshifted with a median velocity that suggests the presence of a molecular outflow, although characterized by a modest molecular mass loss rate of $\sim200~M_{\odot}~{\rm yr}^{-1}$. This value is comparable to the small mass outflow rates found in the stacking of the [CII] spectra of other $z\sim6$ QSOs and suggests that ejective feedback in this phase of the evolution of ULAS J131911+095051 has subsided.

[4]  arXiv:1912.05549 [pdf, other]

Title: A Catalog of M-dwarf Flares with ASAS-SN

Authors: Romy Rodríguez Martínez, Laura A. Lopez, Benjamin J. Shappee, Sarah J. Schmidt, Tharindu Jayasinghe, Christopher S. Kochanek, Katie Auchettl, Thomas W.-S. Holoien

Comments: 16 pages, 5 figures, 7 tables, submitted to the AAS Journals

Subjects: Solar and Stellar Astrophysics (astro-ph.SR)

We analyzed the light curves of 1376 early-to-late, nearby M dwarfs to search for white-light flares using photometry from the All-Sky Automated Survey for Supernovae (ASAS-SN). We identified 480 M dwarfs with at least one potential flare employing a simple statistical algorithm that searches for sudden increases in $V$-band flux. After more detailed evaluation, we identified 62 individual flares on 62 stars. The event amplitudes range from $0.12 <\Delta V < 2.04$ mag. Using classical-flare models, we place lower limits on the flare energies and obtain $V$-band energies spanning $2.0\times10^{30} \lesssim E_{V} \lesssim 6.9\times10^{35}$ erg. The fraction of flaring stars increases with spectral type, and most flaring stars show moderate to strong H$\alpha$ emission. Additionally, we find that 14 of the 62 flaring stars are rotational variables, and they have shorter rotation periods and stronger H$\alpha$ emission than non-flaring rotational variable M dwarfs.

[5]  arXiv:1912.05551 [pdf, other]

Title: HST/WFC3 grism observations of $z\sim1$ clusters: evidence for evolution in the mass-size relation of quiescent galaxies from poststarburst galaxies

Authors: Jasleen Matharu, Adam Muzzin, Gabriel B. Brammer, Remco F.J. van der Burg, Matthew W. Auger, Paul C. Hewett, Jeffrey C.C. Chan, Ricardo Demarco, Pieter van Dokkum, Danilo Marchesini, Erica J. Nelson, Allison G. Noble, Gillian Wilson

Comments: 22 pages, 10 figures, awaiting response to first revision from MNRAS

Subjects: Astrophysics of Galaxies (astro-ph.GA)

Minor mergers have been proposed as the driving mechanism for the size growth of quiescent galaxies with decreasing redshift. The process whereby large star-forming galaxies quench and join the quiescent population at the large size end has also been suggested as an explanation for this size growth. Given the clear association of quenching with clusters, we explore this mechanism by studying the structural properties of 23 spectroscopically identified recently quenched (or "poststarburst" (PSB)) cluster galaxies at $z\sim1$. Despite clear PSB spectral signatures implying rapid and violent quenching, $87\%$ of these galaxies have symmetric, undisturbed morphologies in the stellar continuum. Remarkably, they follow a mass-size relation lying midway between the star-forming and quiescent field relations. This implies a rapid change in the light profile without directly effecting the stellar distribution, suggesting changes in the mass-to-light ratio gradients across the galaxy are responsible. We develop fading toy models to explore how star-forming galaxies move across the mass-size plane as their stellar populations fade to match those of the PSBs. Modelling a galaxy with a bulge+disc, and fading the disc from the "outside-in", can lead to the contraction in size and increase in bulge-dominance observed between star-forming and PSB cluster galaxies. Since cluster PSBs lie on the large size end of the quiescent mass-size relation, and our previous work shows cluster galaxies are smaller than field galaxies, the sizes of quiescent galaxies must grow both from the quenching of star-forming galaxies and dry minor mergers.

[6]  arXiv:1912.05552 [pdf, other]

Title: The young planetary system K2-25: constraints on companions and starspots

Authors: Isabel J. Kain, Elisabeth R. Newton, Jason A. Dittmann, Jonathan M. Irwin, Andrew W. Mann, Pa Chia Thao, David Charbonneau, Jennifer G. Winters

Comments: Accepted for publication to IOP journals. Transit and monitoring lightcurves available in the published version of this manuscript or upon request to I. Kain and E. Newton

Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)

The abundance of planets with orbital periods of a few to tens of days suggests that exoplanets experience complex dynamical histories. Planets in young stellar clusters or associations have well-constrained ages and therefore provide an opportunity to explore the dynamical evolution of exoplanets. K2-25b is a Neptune-sized planet in an eccentric, 3.48 day orbit around an M4.5 dwarf star in the Hyades cluster (650 Myr). In order to investigate its non-zero eccentricity and tight orbit, we analyze transit timing variations (TTVs) which could reveal clues to the migration processes that may have acted on the planet. We obtain 12 non-consecutive transits using the MEarth Observatories and long-term photometric monitoring, which we combine with 10 transits from the Spitzer Space Telescope and 20 transits from K2. Tables of MEarth photometry accompany this work. We fit each transit lightcurve independently. We first investigate whether inhomogeneities on the stellar surface (such as spots or plages) are differentially affecting our transit observations. The measured transit depth does not vary significantly between transits, though we see some deviations from the fiducial transit model. We then looked for TTVs as evidence of a non-transiting perturber in the system. We find no evidence for > 1 $M_\oplus$ companions within a 2:1 period ratio, or for > 5 $M_\oplus$ planets within a 7:2 period ratio.

[7]  arXiv:1912.05555 [pdf, other]

Title: It is Feasible to Directly Measure Black Hole Masses in the First Galaxies

Authors: Hamsa Padmanabhan (CITA), Abraham Loeb (Harvard)

Comments: 5 pages; 2 figures

Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)

In the local universe, black hole masses have been inferred from the observed increase in the velocities of stars at the centres of their host galaxies. So far, masses of supermassive black holes in the early universe have only been inferred indirectly, using relationships calibrated to their locally observed counterparts. Here, we use the latest observational constraints on the evolution of stellar masses in galaxies to predict that the region of influence of a central supermassive black hole at the epochs where the first galaxies were formed is $\mathit{directly \ resolvable}$ by current and upcoming telescopes. Such measurements will usher in a new era of discoveries unraveling the formation of the first supermassive black holes based on subarcsecond-scale spectroscopy with the $ALMA$, $JWST$ and the $SKA$. The measured mass distribution of black holes will allow forecasting of the future detection of gravitational waves from the earliest black hole mergers.

[8]  arXiv:1912.05556 [pdf, ps, other]

Title: GJ 1252 b: A 1.2 $R_{\oplus}$ planet transiting an M-dwarf at 20.4 pc

Authors: Avi Shporer, Karen A. Collins, Nicola Astudillo-Defru, Jonathan Irwin, Xavier Bonfils, Kevin I. Collins, Elisabeth Matthews, Jennifer G. Winters, David R. Anderson, James D. Armstrong, David Charbonneau, Ryan Cloutier, Tansu Daylan, Tianjun Gan, Maximilian N. Günther, Coel Hellier, Keith Horne, Chelsea X. Huang, Eric L. N. Jensen, John Kielkopf, Ramotholo Sefako, Keivan G. Stassun, Thiam-Guan Tan, Andrew Vanderburg, George R. Ricker, David W. Latham, Roland Vanderspek, Sara Seager, Joshua N. Winn, Jon M. Jenkins, Knicole Colon, Courtney D. Dressing, Sébastien Lépine, Philip S. Muirhead, Mark E. Rose, Joseph D. Twicken, Jesus Noel Villasenor

Comments: Submitted to AAS journals. Comments welcome

Subjects: Earth and Planetary Astrophysics (astro-ph.EP)

We report the discovery of GJ 1252 b, a planet with a radius of 1.193 $\pm$ 0.074 $R_{\oplus}$ and an orbital period of 0.52 days around an M3-type star (0.381 $\pm$ 0.019 $M_{\odot}$, 0.391 $\pm$ 0.020 $R_{\odot}$) located 20.4 pc away. We use TESS data, ground-based photometry and spectroscopy, Gaia astrometry, and high angular resolution imaging to show that the transit signal seen in the TESS data must originate from a transiting planet. We do so by ruling out all false positive scenarios that attempt to explain the transit signal as originating from an eclipsing stellar binary. Precise Doppler monitoring also leads to a tentative mass measurement of 2.09 $\pm$ 0.56 $M_{\oplus}$. The host star proximity, brightness ($V$ = 12.19 mag, $K$ = 7.92 mag), low stellar activity, and the system's short orbital period make this planet an attractive target for detailed characterization.

[9]  arXiv:1912.05557 [pdf, other]

Title: Empirical Validation of the Ising Galaxy Bias Model

Authors: Andrew Repp, István Szapudi

Comments: 22 pages, 16 figures; submitted to MNRAS

Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)

Repp and Szapudi (2019) present a physically-motivated galaxy bias model which remains physical in low-density regions and which also provides a better fit to simulation data than do typical survey-analysis bias models. Given plausible simplifying assumptions, the physics of this model (surprisingly) proves to be analogous to the Ising model of statistical mechanics. In the present work we present a method of testing this Ising bias model against empirical galaxy survey data. Using this method, we compare our model (as well as three reference models -- linear, quadratic, and logarithmic) to SDSS, 6dFGS, and COSMOS2015 results, finding that for spectroscopic redshift surveys, the Ising bias model provides a superior fit compared to the reference models. Photometric redshifts, on the other hand, introduce enough error into the radial coordinate that none of the models yields a good fit. A physically meaningful galaxy bias model is necessary for optimal extraction of cosmological information from dense galaxy surveys such as Euclid and WFIRST.

[10]  arXiv:1912.05560 [pdf, other]

Title: On the initial mass-radius relation of stellar clusters

Authors: Nick Choksi, J.M. Diederik Kruijssen

Comments: 13 pages. MNRAS submitted. Comments welcome

Subjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)

Young stellar clusters across nearly five orders of magnitude in mass appear to follow a simple mass-radius relationship (MRR), $R_{\star} \propto M_{\star}^{\alpha}$, with $\alpha \approx 0.2 - 0.33$. Here, we develop a simple analytic model to explain this observation. We begin by considering giant molecular clouds near virial equilibrium and subsequently relate the properties of the cluster to those of the cloud. In turn, we relate the cloud properties to those of the large-scale galactic environment. The model predicts an \textit{initial} mass-radius relation of constant surface density, $R_{\star} \propto M_{\star}^{1/2}$. It also predicts the initial cluster radius depends on the large-scale gas density $\Sigma_g$ of the ambient ISM, scaling as $R_{\star} \propto \Sigma_g^{-1/2}$. We argue that the tendency of observed clusters to fall along lines of shallower MRRs than our initial $R_{\star} \propto M_{\star}^{1/2}$ is in fact a combination of two effects. The fact that massive clusters can \textit{only} form in high gas-density environments, when combined with the $R_{\star} \propto \Sigma_g^{-1/2}$ scaling we find here, ultimately shallows the global slope at high masses to nearly $R_{\star} \propto M_{\star}^{1/3}$. Meanwhile, at low masses relaxation-driven expansion quickly shallows the MRR. We combine our predicted MRR with a simple population synthesis model and apply it to a range of star-forming environments, from nearby disc galaxies to nuclear starbursts, and find good agreement throughout. We provide quantitative predictions for the radii of proto-globular clusters (GCs) and discuss the implications of the model for GC evolution and survival across cosmic time as well as the dynamical assembly of black hole binaries in stellar clusters.

[11]  arXiv:1912.05563 [pdf, other]

Title: Light Dark Matter: A Common Solution to the Lithium and ${H_0}$ Problems

Authors: Jailson Alcaniz, Nicolás Bernal, Antonio Masiero, Farinaldo S. Queiroz

Comments: 5 pages, 2 figures

Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph)

Currently, the standard cosmological model faces some tensions and discrepancies between observations at early and late cosmological time. One of them concerns the well-known $H_0$-tension problem, i.e., a $\sim4.4\sigma$-difference between the early-time estimate and late-time measurements of the Hubble constant, $H_0$. Another puzzling question rests in the cosmological lithium abundance, where again local measurements differ from the one predicted by Big Bang Nucleosynthesis (BBN). In this work, we show that a mechanism of light dark matter production might hold the answer for these questions. If dark matter particles are sufficiently light and a fraction of them was produced non-thermally in association with photons, this mechanism has precisely what is needed to destroy Lithium without spoiling other BBN predictions. Besides, it produces enough radiation that leads to a larger $H_0$ value, reconciling early and late-time measurements of the Hubble expansion rate without leaving sizable spectral distortions in the Cosmic Microwave Background spectrum.

[12]  arXiv:1912.05582 [pdf, other]

Title: Constraining the second half of reionization with the Lyman-$β$ forest

Authors: Laura C. Keating, Girish Kulkarni, Martin G. Haehnelt, Jonathan Chardin, Dominique Aubert

Comments: 10 pages, 8 figures, 1 table. Submitted to MNRAS

Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA)

We present an analysis of the evolution of the Lyman-series forest into the epoch of reionization using cosmological radiative transfer simulations in a scenario where reionization ends late. We explore models with different midpoints of reionization and gas temperatures. We find that once the simulations have been calibrated to match the mean flux of the observed Lyman-$\alpha$ forest at $4 < z < 6$, they also naturally reproduce the distribution of effective optical depths of the Lyman-$\beta$ forest in this redshift range. We note that the tail of the largest optical depths that is most challenging to match corresponds to the long absorption trough of ULAS J0148+0600, which we have previously shown to be rare in our simulations. We consider the evolution of the Lyman-series forest out to higher redshifts, and show that future observations of the Lyman-$\beta$ forest at $z>6$ will discriminate between different reionization histories. The evolution of the Lyman-$\alpha$ and Lyman-$\gamma$ forests are less promising as a tool for pushing studies of reionization to higher redshifts due to the stronger saturation and foreground contamination, respectively.

[13]  arXiv:1912.05592 [pdf, other]

Title: Effects of chaos on the detectability of stellar streams

Authors: Martín Mestre, Claudio Llinares, Daniel D. Carpintero

Subjects: Astrophysics of Galaxies (astro-ph.GA); Chaotic Dynamics (nlin.CD)

Observations show that stellar streams originating in satellite dwarf galaxies are frequent in the Universe. While such events are predicted by theory, it is not clear how many of the streams that are generated are washed out afterwards to the point in which it is imposible to detect them. Here we study how these diffusion times are affected by the fact that typical gravitational potentials of the host galaxies can sustain chaotic orbits. We do this by comparing the behaviour of simulated stellar streams that reside in chaotic or non-chaotic regions of the phase-space. We find that chaos does reduce the time interval in which streams can be detected. By analyzing detectability criteria in configuration and velocity space, we find that the impact of these results on the observations depends on the quality of both the data and the underlying stellar halo model. For all the stellar streams, we obtain a similar upper limit to the detectable mass.

[14]  arXiv:1912.05593 [pdf, ps, other]

Title: Spherical Rectangular Equal-Area Grid (SREAG): Some features

Authors: Zinovy Malkin

Comments: Presented at the Journees 2019 "Astrometry, Earth rotation and Reference systems in the Gaia era", Paris, France, 7-9 Oct 2019. Supporting routines are included in the distribution

Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)

A new method Spherical Rectangular Equal-Area Grid (SREAG) was proposed in Malkin (2019) for splitting spherical surface into equal-area rectangular cells. In this work, some more detailed features of SREAG are presented. The maximum number of rings that can be achieved with SREAG for coding with 32-bit integer is $N_{ring}$=41068, which corresponds to the finest resolution of $\sim$16$''$. Computational precision of the SREAG is tested. The worst level of precision is $7\cdot10^{-12}$ for large $N_{ring}$. Simple expressions were derived to calculate the number of rings for the desired number of cells and for the required resolution.

[15]  arXiv:1912.05605 [pdf, other]

Title: The Role of Magnetic Fields in Protostellar Outflows and Star Formation

Authors: Ralph E. Pudritz, Tom P. Ray

Comments: 53 pages, 14 figures

Journal-ref: Frontiers in Astronomy and Space Sciences, Volume 6, id.54 (2019)

Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP); High Energy Astrophysical Phenomena (astro-ph.HE)

The role of outflows in the formation of stars and the protostellar disks that generate them is a central question in astrophysics. Outflows are associated with star formation across the entire stellar mass spectrum. In this review, we describe the observational, theoretical, and computational advances on magnetized outflows, and their role in the formation of disks and stars of all masses in turbulent, magnetized clouds. The ability of torques exerted on disks by magnetized winds to efficiently extract and transport disk angular momentum was developed in early theoretical models and confirmed by a variety of numerical simulations. The recent high resolution ALMA observations of disks and outflows now confirm several key aspects of these ideas, e.g. that jets rotate and originate from large regions of their underlying disks. New insights on accretion disk physics show that magneto-rotational instability (MRI) turbulence is strongly damped, leaving magnetized disk winds as the dominant mechanism for transporting disk angular momentum. This has major consequences for star formation, as well as planet formation. Outflows also play an important role in feedback processes particularly in the birth of low mass stars and cluster formation. Despite being almost certainly fundamental to their production and focusing, magnetic fields in outflows in protostellar systems, and even in the disks, are notoriously difficult to measure. Most methods are indirect and lack precision, as for example, when using optical/near-infrared line ratios. Moreover, in those rare cases where direct measurements are possible - where synchrotron radiation is observed, one has to be very careful in interpreting derived values. Here we also explore what is known about magnetic fields from observations, and take a forward look to the time when facilities such as SPIRou and the SKA are in routine operation.

[16]  arXiv:1912.05613 [pdf, ps, other]

Title: Outstanding Pulkovo latitude observers Lidia Kostina and Natalia Persiyaninova

Authors: Zinovy Malkin, Natalia Miller, Tatiana Soboleva

Comments: Presented at the Journees 2019 "Astrometry, Earth rotation and Reference systems in the Gaia era", Paris, France, 7-9 Oct 2019

Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); History and Philosophy of Physics (physics.hist-ph)

Lidia Dmitrievna Kostina and Natalia Romanovna Persiyaninova left a bright mark in the history of the Pulkovo Observatory, as well as in the history of the domestic and international latitude services. In the first place, they were absolute leaders in the latitude observations with the famous zenith telescope ZTF-135. In 1954-2001, they obtained together more than 66'000 highly accurate latitudes, which make about 2/3 of all the observations made by 23 observers with the ZTF-135 after the WW2. They also provided a large contribution to investigation of the instrumental errors, methods of the data analysis, developing of the observing programs. Their results in studies of the latitude variations and polar motion were also highly recognized by the community.

[17]  arXiv:1912.05614 [pdf, other]

Title: The Million Quasars (Milliquas) Catalogue, v6.4

Authors: Eric W. Flesch

Comments: Announcement only, 6 pages. Journal publication of Milliquas awaiting completion of SDSS-IV

Subjects: Astrophysics of Galaxies (astro-ph.GA)

Announcing the release v6.4 of the Milliquas (Million Quasars) quasar catalogue which presents all published quasars to 11 December 2019, including SDSS-DR16. Its totals are 757,991 type-I QSOs/AGN and approx 1.1M high-confidence (80%+ likelihood) quasar candidates from SDSS-based & AllWISE photometric quasar catalogs, plus all-sky radio/X-ray associated candidates available only here. Type-II and Bl Lac objects are also included, plus candidates/galaxies with double radio lobes (so calculated), bringing the total count to 1,968,377. Gaia-DR2 astrometry is given for most objects. The catalogue is available on its home page and on NASA HEASARC.

[18]  arXiv:1912.05623 [pdf, other]

Title: Effects of photoevaporation on protoplanetary disc `isochrones'

Authors: Alice Somigliana, Claudia Toci, Giuseppe Lodato, Giovanni Rosotti, Carlo Felice Manara

Comments: 8 pages, 7 figures. Accepted for publication on MNRAS

Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)

Protoplanetary discs are the site of star and planet formation, and their evolution and consequent dispersal deeply affect the formation of planetary systems. In the standard scenario they evolve on timescales ~Myr due to the viscous transport of angular momentum. The analytical self-similar solution for their evolution predicts also specific disc isochrones in the accretion rate - disc mass plane. However, photoevaporation by radiation emitted by the central star is likely to dominate the gas disc dispersal of the innermost region, introducing another (shorter) timescale for this process. In this paper, we include the effect of internal (X and EUV) photoevaporation on the disc evolution, finding numerical solutions for a population of protoplanetary discs. Our models naturally reproduce the expected quick dispersal of the inner region of discs when their accretion rates match the rate of photoevaporative mass loss, in line with previous studies. We find that photoevaporation preferentially removes the lightest discs in the sample. The net result is that, counter-intuitively, photoevaporation increases the average disc mass in the sample, by dispersing the lightest discs. At the same time, photoevaporation also reduces the mass accretion rate by cutting the supply of material from the outer to the inner disc. In a purely viscous framework, this would be interpreted as the result of a longer viscous evolution, leading to an overestimate of the disc age. Our results thus show that photoevaporation is a necessary ingredient to include when interpreting observations of large disc samples with measured mass accretion rates and disc masses. Photoevaporation leaves a characteristic imprint on the shape of the isochrone. Accurate data in the accretion rate - disc mass plane in the low disc mass region therefore give clues on the typical photoevaporation rate.

[19]  arXiv:1912.05627 [pdf, other]

Title: The Hubble Space Telescope Advanced Camera for Surveys Emission Line Survey of Andromeda I: Classical Be Stars

Authors: M. Peters, J.P. Wisniewski, B.F. Williams, J.R. Lomax, Y. Choi, M. Durbin, L.C. Johnson, A.R. Lewis, J. Lutz, T.A.A. Sigut, A. Wallach, J.J. Dalcanton

Comments: Submitted to AJ

Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)

We present results from a 12-orbit, 2-epoch HST H$\alpha$ emission line survey of the Andromeda Galaxy that overlaps the footprint of the Panchromatic Hubble Andromeda Treasury (PHAT) survey. Out of $\sim$2 million sources detected in each epoch, we find 552 (542) classical Be stars and 8429 (8556) normal B-type stars in epoch # 1 (epoch # 2), yielding an overall fractional Be content of 6.15% $\pm$0.26% (5.96% $\pm$0.25%). Using PHAT photometry, we find that the fractional Be content decreased with spectral sub-type from $\sim$23.6% $\pm$2.0% ($\sim$23.9% $\pm$2.0%) for B0-type stars to $\sim$3.1% $\pm$0.34% ($\sim$3.4% $\pm$0.35%) for B8-type stars in epoch # 1 (epoch # 2). Compared to the SMC, Be stars are 2.8x rarer in M31 for the earliest sub-types. Our data provide confirmation that the fractional Be content in more metal rich environments (the Milky Way and M31) is lower than that observed in metal poor environments (LMC and SMC). We observe a clear population of cluster Be stars at early fractional main sequence lifetimes, indicating that a subset of Be stars emerge onto the ZAMS as rapid rotators. Our data indicate no clear change in the frequency of early-type Be stars in M31 and Milky Way, despite their different metallicity, which may reflect that the Be phenomenon is enhanced with evolutionary age. Interestingly, the rate of disk-loss or disk-regeneration episodes we observe between our two epoch Be sample, 22% $\pm$ 2% yr$^{-1}$, is similar to observed for NGC 3766 (17.3 $\pm$ 3% yr$^{-1}$) and 6 other Galactic clusters (20.5 $\pm$ 4.5% yr$^{-1}$), assuming these latter transient fractions scale by a linear rate. Finally, we observed a similar number of disk-loss events (57) as disk-renewal events (43), which was unexpected as disk dissipation time-scales can be $\sim$2x the typical time-scales for disk build-up phases.

[20]  arXiv:1912.05628 [pdf, ps, other]

Title: FLAMINGOS-2 infrared photometry of 2I/Borisov

Authors: Chien-Hsiu Lee (NSF's OIR Lab), Hsing-Wen Lin (University of Michigan), Ying-Tung Chen (ASIAA), Sheng-Feng Yen (ASIAA)

Comments: 3 pages, 1 figure

Journal-ref: RNAAS, 2019, 3, 12

Subjects: Earth and Planetary Astrophysics (astro-ph.EP)

2I/Borisov is the second interstellar object (ISO) after 'Oumuamua (Meech et al. 2017), but differs from 'Oumuamua drastically with its extensive cometary activity. A key ingredient to understand the nature of this comet is its size. However, due to its cometary activity and extended coma in the optical, only rough estimates and upper limits can be made for 2I/Borisov, ranging in a wide spread from 0.7 to 3.8 km (Guzik et al. 2019; Fitzsimmons et al. 2019; Jewitt, & Luu 2019; Bolin et al. 2019). It has been shown that observations at longer wavelengths (i.e. infrared) are less susceptible to the effects of coma, and can provide a better estimate of the size of the comet nucleus (see, e.g., Fern\'andez et al. 2013; Bauer et al. 2017). Here we present an estimate of the nucleus of 2I/Borisov from infrared observations by FLAMINGOS-2 on-board the Gemini South telescope (under Fast Turnaround program GS-2019B-FT-207), and infer a comet nucleus size of 1.5 km, comparable to but more stringent than the estimate from Keck AO imaging by Bolin et al. (2019).

[21]  arXiv:1912.05630 [pdf]

Title: Measurements and semi-empirical calculations of CO2+CH4 and CO2+H2 collision-induced absorptions across a wide range of wavenumbers and temperatures. Application for the prediction of early Mars surface temperature

Authors: Martin Turbet, Christian Boulet, Tijs Karman

Comments: Submitted for publication to Icarus. CO2+H2 and CO2+CH4 CIAs calculated tables (HITRAN format) - as well as predicted early Mars surface temperatures - are available on demand

Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Atmospheric and Oceanic Physics (physics.ao-ph); Atomic and Molecular Clusters (physics.atm-clus); Chemical Physics (physics.chem-ph)

Reducing atmospheres have recently emerged as a promising scenario to warm the surface of early Mars enough to drive the formation of valley networks and other ancient aqueous features that have been detected so far on the surface of Mars. Here we present a series of experiments and calculations to better constrain CO2+CH4 and CO2+H2 collision-induced absorptions (CIAs) as well as their effect on the prediction of early Mars surface temperature. First, we carried out a new set of experimental measurements (using the AILES line of the SOLEIL synchrotron) of both CO2+CH4 and CO2+H2 CIAs. These measurements confirm the previous results of Turbet et al. 2019, Icarus vol. 321, while significantly reducing the experimental uncertainties. Secondly, we fitted a semi-empirical model to these CIAs measurements, allowing us to compute the CO2+CH4 and CO2+H2 CIAs across a broad spectral domain (0-1500cm-1) and for a wide range of temperatures (100-600K). Last, we performed 1-D numerical radiative-convective climate calculations (using the LMD Generic Model) to compute the surface temperature expected on the surface of early Mars for several CO2, CH4 and H2 atmospheric contents, taking into account the radiative effect of these revised CIAs. These calculations demonstrate that thick CO2+H2-dominated atmospheres remain a viable solution for warming the surface of Mars above the melting point of water, but not CO2+CH4-dominated atmospheres. Our calculated CO2+CH4 and CO2+H2 CIA spectra and predicted early Mars surface temperatures are provided to the community for future uses.

[22]  arXiv:1912.05632 [pdf, ps, other]

Title: Search for Gamma-ray Spectral Lines from Dark Matter Annihilation in Dwarf Galaxies with the High-Altitude Water Cherenkov Observatory

Authors: The HAWC Collaboration

Comments: submitted to PRD

Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Experiment (hep-ex)

Local dwarf spheroidal galaxies (dSphs) are nearby dark-matter dominated systems, making them excellent targets for searching for gamma rays from particle dark matter interactions. If dark matter annihilates or decays directly into two gamma rays (or a gamma ray and a neutral particle), a monochromatic spectral line is created. At TeV energies, no other processes are expected to produce spectral lines, making this a very clean indirect dark matter search channel. With the development of event-by-event energy reconstruction, we can now search for spectral lines with the High Altitude Water Cherenkov (HAWC) Observatory. HAWC is a wide field of view survey instrument located in central Mexico that observes gamma rays from <1 TeV to >100 TeV. In this work we present results from a recent search for spectral lines from local, dark matter dominated dwarf galaxies using 1038 days of HAWC data. We also present updated limits on several continuum channels that were reported in a previous publication. Our gamma-ray spectral line limits are the most constraining obtained so far from 20 TeV to 100 TeV.

[23]  arXiv:1912.05659 [pdf, other]

Title: The electromagnetic counterparts of compact binary mergers

Authors: Ehud Nakar

Comments: A review, submitted to Physics Reports

Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

Mergers of binaries consisting of two neutron stars, or a black hole and a neutron star, offer a unique opportunity to study a range of physical and astrophysical processes using two different and almost orthogonal probes - gravitational waves (GW) and electromagnetic (EM) emission. The GW signal probes the binary and the physical processes that take place during the last stages of the merger, while the EM emission provides clues to the material that is thrown out following the merger. The accurate localization, which only the EM emission can provide, also indicates the astrophysical setting in which the merger took place. In addition, the combination of the two signals provides constraints on the nature of gravity and on the expansion rate of the Universe. The first detection of a binary neutron star merger by the LIGO-Virgo collaboration, GW170817, initiated the era of multi-messenger GW-EM astrophysics and demonstrated the great promise it holds. The event produced an unprecedented data set, and although it was only a single event, it provided remarkable results that revolutionized our knowledge of neutron star mergers. GW170817 is especially exciting since we know that it is not one of a kind and that many more events will be detected during the next decade. In this review, I summarize, first, the theory of EM emission from compact binary mergers, highlighting the unique information that the combined GW-EM detection provides. I then describe the entire set of GW and EM observations of GW170817, and summarize the range of insights that it offers. This includes clues about the role that similar events play in the r-process elements budget of the Universe, the neutron star equation of state, the properties of the relativistic outflow that followed the merger, and the connection between neutron star binary mergers and short gamma-ray bursts.

[24]  arXiv:1912.05668 [pdf, ps, other]

Title: The Subaru HSC Galaxy Clustering with Photometric Redshift I: Dark Halo Masses Versus Baryonic Properties of Galaxies at 0.3<z<1.4

Authors: Shogo Ishikawa, Nobunari Kashikawa, Masayuki Tanaka, Jean Coupon, Alexie Leauthaud, Jun Toshikawa, Kohei Icihkawa, Taira Oogi, Hiasakazu Uchiyama, Yuu Niino, Atsushi J. Nishizawa

Comments: 33 pages, 16 figures, submitted to ApJ

Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)

We present the clustering properties of low-$z$ $(z\leq1.4)$ galaxies selected by the Hyper Suprime-Cam Subaru Strategic Program Wide layer over $145$ deg$^{2}$. The wide-field and multi-wavelength observation yields $5,064,770$ galaxies at $0.3\leq z\leq1.4$ with photometric redshifts and physical properties. This enables the accurate measurement of angular correlation functions and subsequent halo occupation distribution (HOD) analysis allows the connection between baryonic properties and dark halo properties. The fraction of less-massive satellite galaxies at $z\lesssim1$ is found to be almost constant at $\sim20\%$, but it gradually decreases beyond $M_{\star} \sim 10^{10.4}h^{-2}M_{\odot}$. However, the abundance of satellite galaxies at $z>1$ is quite small even for less-massive galaxies due to the rarity of massive centrals at high-$z$. This decreasing trend is connected to the small satellite fraction of Lyman break galaxies at $z>3$. The stellar-to-halo mass ratios at $0.3\leq z\leq1.4$ are almost consistent with the predictions obtained using the latest empirical model; however, we identify small excesses from the theoretical model at the massive end. The pivot halo mass is found to be unchanged at $10^{11.9-12.1}h^{-1}M_{\odot}$ at $0.3\leq z\leq1.4$, and we systematically show that $10^{12}h^{-1}M_{\odot}$ is a universal pivot halo mass up to $z\sim5$ that is derived using only the clustering/HOD analyses. Nevertheless, halo masses with peaked instantaneous baryon conversion efficiencies are much smaller than the pivot halo mass regardless of a redshift, and the most efficient stellar-mass assembly is thought to be in progress in $10^{11.0-11.5}h^{-1}M_{\odot}$ dark haloes.

[25]  arXiv:1912.05673 [pdf, other]

Title: Circalunar variations of the night sky brightness -- an FFT perspective on the impact of light pollution

Authors: Johannes Puschnig, Stefan Wallner, Thomas Posch

Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)

Circa-monthly activity conducted by moonlight is observed in many species on Earth. Given the vast amount of artificial light at night (ALAN) that pollutes large areas around the globe, the synchronization to the circalunar cycle is often strongly perturbed. Using two-year data from a network of 23 photometers (Sky Quality Meters; SQM) in Austria (latitude ~48{\deg}), we quantify how light pollution impacts the recognition of the circalunar periodicity. We do so via frequency analysis of nightly mean sky brightnesses using Fast Fourier Transforms. A very tight linear relation between the mean zenithal night sky brightness (NSB) given in mag$_{SQM}$ and the amplitude of the circalunar signal is found, indicating that for sites with a mean zenithal NSB brighter than 16.5 mag$_{SQM}$ the lunar rhythm practically vanishes. This finding implies that the circalunar rhythm is still detectable (within the broad bandpass of the SQM) at most places around the globe, but its amplitude against the light polluted sky is strongly reduced. We find that the circalunar contrast in zenith is reduced compared to ALAN-free sites by factors of 1/9 in the state capital of Linz (~200,000 inhabitants) and 1/3 in small towns, e.g. Freistadt and Mattighofen, with less than 10,000 inhabitants. Only two of our sites, both situated in national parks (Bodinggraben and Z\"oblboden), show natural circalunar amplitudes. At our urban sites we further detect a strong seasonal signal that is linked to the amplification of anthropogenic skyglow during the winter months due to climatological conditions.

[26]  arXiv:1912.05701 [pdf, other]

Title: Constraining Black Hole Populations in Globular Clusters using Microlensing: Application to Omega Centauri

Authors: John Zaris, Doğa Veske, Johan Samsing, Zsuzsa Márka, Imre Bartos, Szabolcs Márka

Comments: 6 pages, 2 figures

Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

We estimate the rate of gravitational microlensing events of cluster stars due to black holes (BHs) in the globular cluster NGC 5139 ($\omega Cen$). Theory and observations both indicate that $\omega Cen$ contains thousands of BHs, but their mass spectrum and exact distribution are not well constrained. In this Letter we show that one is able to observe microlensing events on a timescale of years in $\omega Cen$, and such an event sample can be used to infer the BH distribution. Direct detection of BHs will, in the near future, play a major role in distinguishing binary BH merger channels. Here we explore how gravitational microlensing can be used to put constraints on BH populations in globular clusters.

[27]  arXiv:1912.05702 [pdf, other]

Title: A NICER View of PSR J0030+0451: Millisecond Pulsar Parameter Estimation

Authors: Thomas E. Riley, Anna L. Watts, Slavko Bogdanov, Paul S. Ray, Renee M. Ludlam, Sebastien Guillot, Zaven Arzoumanian, Charles L. Baker, Anna V. Bilous, Deepto Chakrabarty, Keith C. Gendreau, Alice K. Harding, Wynn C. G. Ho, James M. Lattimer, Sharon M. Morsink, Tod E. Strohmayer

Comments: Appears in ApJ Letters Focus Issue on NICER Constraints on the Dense Matter Equation of State; 76 pages, 24 figures, 7 tables, 8 figure sets (available in the online journal or from the authors)

Journal-ref: ApJL, 887, L21 (2019)

Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Theory (nucl-th)

We report on Bayesian parameter estimation of the mass and equatorial radius of the millisecond pulsar PSR J0030$+$0451, conditional on pulse-profile modeling of Neutron Star Interior Composition Explorer (NICER) X-ray spectral-timing event data. We perform relativistic ray-tracing of thermal emission from hot regions of the pulsar's surface. We assume two distinct hot regions based on two clear pulsed components in the phase-folded pulse-profile data; we explore a number of forms (morphologies and topologies) for each hot region, inferring their parameters in addition to the stellar mass and radius. For the family of models considered, the evidence (prior predictive probability of the data) strongly favors a model that permits both hot regions to be located in the same rotational hemisphere. Models wherein both hot regions are assumed to be simply-connected circular single-temperature spots, in particular those where the spots are assumed to be reflection-symmetric with respect to the stellar origin, are strongly disfavored. For the inferred configuration, one hot region subtends an angular extent of only a few degrees (in spherical coordinates with origin at the stellar center) and we are insensitive to other structural details; the second hot region is far more azimuthally extended in the form of a narrow arc, thus requiring a larger number of parameters to describe. The inferred mass $M$ and equatorial radius $R_\mathrm{eq}$ are, respectively, $1.34_{-0.16}^{+0.15}$ M$_{\odot}$ and $12.71_{-1.19}^{+1.14}$ km, whilst the compactness $GM/R_\mathrm{eq}c^2 = 0.156_{-0.010}^{+0.008}$ is more tightly constrained; the credible interval bounds reported here are approximately the $16\%$ and $84\%$ quantiles in marginal posterior mass.

[28]  arXiv:1912.05703 [pdf, other]

Title: A NICER view of PSR J0030+0451: Implications for the dense matter equation of state

Authors: G. Raaijmakers, T. E. Riley, A. L. Watts, S. K. Greif, S. M. Morsink, K. Hebeler, A. Schwenk, T. Hinderer, S. Nissanke, S. Guillot, Z. Arzoumanian, S. Bogdanov, D. Chakrabarty K. C. Gendreau, W. C. G. Ho, J. M. Lattimer, R. M. Ludlam, M. T. Wolff

Comments: Appears in ApJ Letters Focus Issue on NICER Constraints on the Dense Matter Equation of State, 17 pages, 5 figures

Journal-ref: ApJ Letters, 887, L22 (2019)

Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Theory (nucl-th)

Both the mass and radius of the millisecond pulsar PSR J0030+0451 have been inferred via pulse-profile modeling of X-ray data obtained by NASA's NICER mission. In this Letter we study the implications of the mass-radius inference reported for this source by Riley et al. (2019) for the dense matter equation of state (EOS), in the context of prior information from nuclear physics at low densities. Using a Bayesian framework we infer central densities and EOS properties for two choices of high-density extensions: a piecewise-polytropic model and a model based on assumptions of the speed of sound in dense matter. Around nuclear saturation density these extensions are matched to an EOS uncertainty band obtained from calculations based on chiral effective field theory interactions, which provide a realistic description of atomic nuclei as well as empirical nuclear matter properties within uncertainties. We further constrain EOS expectations with input from the current highest measured pulsar mass; together, these constraints offer a narrow Bayesian prior informed by theory as well as laboratory and astrophysical measurements. The NICER mass-radius likelihood function derived by Riley et al. (2019) using pulse-profile modeling is consistent with the highest-density region of this prior. The present relatively large uncertainties on mass and radius for PSR J0030+0451 offer, however, only a weak posterior information gain over the prior. We explore the sensitivity to the inferred geometry of the heated regions that give rise to the pulsed emission, and find a small increase in posterior gain for an alternative (but less preferred) model. Lastly, we investigate the hypothetical scenario of increasing the NICER exposure time for PSR J0030+0451.

[29]  arXiv:1912.05704 [pdf, other]

Title: A NICER view of PSR J0030+0451: evidence for a global-scale multipolar magnetic field

Authors: Anna V. Bilous, Anna L. Watts, Alice K. Harding, Thomas E. Riley, Zaven Arzoumanian, Slavko Bogdanov, Keith C. Gendreau, Paul S. Ray, Sebastien Guillot, Wynn C.G. Ho, Deepto Chakrabarty

Comments: Appears in ApJ Letters Focus Issue on NICER Constraints on the Dense Matter Equation of State

Journal-ref: Bilous et al. 2019, ApJ Letters, 887, L23

Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)

Recent modeling of NICER observations of thermal X-ray pulsations from the surface of the isolated millisecond pulsar PSR J0030+0451 suggests that the hot emitting regions on the pulsar's surface are far from antipodal, which is at odds with the classical assumption that the magnetic field in the pulsar magnetosphere is predominantly that of a centered dipole. Here, we review these results and examine previous attempts to constrain the magnetospheric configuration of PSR J0030+0451. To the best of our knowledge, there is in fact no direct observational evidence that PSR J0030+0451's magnetic field is a centered dipole. Developing models of physically motivated, non-canonical magnetic field configurations and the currents that they can support poses a challenging task. However, such models may have profound implications for many aspects of pulsar research, including pulsar braking, estimates of birth velocities, and interpretations of multi-wavelength magnetospheric emission.

[30]  arXiv:1912.05705 [pdf, other]

Title: PSR J0030+0451 Mass and Radius from NICER Data and Implications for the Properties of Neutron Star Matter

Authors: M. C. Miller, F. K. Lamb, A. J. Dittmann, S. Bogdanov, Z. Arzoumanian, K. C. Gendreau, S. Guillot, A. K. Harding, W. C. G. Ho, J. M. Lattimer, R. M. Ludlam, S. Mahmoodifar, S. M. Morsink, P. S. Ray, T. E. Strohmayer, K. S. Wood, T. Enoto, R. Foster, T. Okajima, G. Prigozhin, Y. Soong

Comments: 49 pages, 16 figures, part of The Astrophysical Journal Letters focus issue on the Neutron Star Interior Composition Explorer

Journal-ref: ApJL 2019, 887, L24

Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)

Neutron stars are not only of astrophysical interest, but are also of great interest to nuclear physicists, because their attributes can be used to determine the properties of the dense matter in their cores. One of the most informative approaches for determining the equation of state of this dense matter is to measure both a star's equatorial circumferential radius $R_e$ and its gravitational mass $M$. Here we report estimates of the mass and radius of the isolated 205.53 Hz millisecond pulsar PSR J0030+0451 obtained using a Bayesian inference approach to analyze its energy-dependent thermal X-ray waveform, which was observed using the Neutron Star Interior Composition Explorer (NICER). This approach is thought to be less subject to systematic errors than other approaches for estimating neutron star radii. We explored a variety of emission patterns on the stellar surface. Our best-fit model has three oval, uniform-temperature emitting spots and provides an excellent description of the pulse waveform observed using NICER. The radius and mass estimates given by this model are $R_e = 13.02^{+1.24}_{-1.06}$ km and $M = 1.44^{+0.15}_{-0.14}\ M_\odot$ (68%). The independent analysis reported in the companion paper by Riley et al. (2019) explores different emitting spot models, but finds spot shapes and locations and estimates of $R_e$ and $M$ that are consistent with those found in this work. We show that our measurements of $R_e$ and $M$ for PSR J0030$+$0451 improve the astrophysical constraints on the equation of state of cold, catalyzed matter above nuclear saturation density.

[31]  arXiv:1912.05706 [pdf, other]

Title: Constraining the Neutron Star Mass-Radius Relation and Dense Matter Equation of State with NICER. I. The Millisecond Pulsar X-ray Data Set

Authors: Slavko Bogdanov, Sebastien Guillot, Paul S. Ray, Michael T. Wolff, Deepto Chakrabarty, Wynn C. G. Ho, Matthew Kerr, Frederick K. Lamb, Andrea Lommen, Renee M. Ludlam, Reilly Milburn, Sergio Montano, M. Coleman Miller, Michi Baubock, Feryal Ozel, Dimitrios Psaltis, Ronald A. Remillard, Thomas E. Riley, James F. Steiner, Tod E. Strohmayer, Anna L. Watts, Kent S. Wood, Jesse Zeldes, Teruaki Enoto, Takashi Okajima, James W. Kellogg, Charles Baker, Craig B. Markwardt, Zaven Arzoumanian, Keith C. Gendreau

Comments: 28 pages, 9 figures; accepted for publication in the Astrophysical Journal Letters

Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

We present the set of deep Neutron Star Interior Composition Explorer (NICER) X-ray timing observations of the nearby rotation-powered millisecond pulsars PSRs J0437-4715, J0030+0451, J1231-1411, and J2124-3358, selected as targets for constraining the mass-radius relation of neutron stars and the dense matter equation of state via modeling of their pulsed thermal X-ray emission. We describe the instrument, observations, and data processing/reduction procedures, as well as the series of investigations conducted to ensure that the properties of the data sets are suitable for parameter estimation analyses to produce reliable constraints on the neutron star mass-radius relation and the dense matter equation of state. We find that the long-term timing and flux behavior and the Fourier-domain properties of the event data do not exhibit any anomalies that could adversely affect the intended measurements. From phase-selected spectroscopy, we find that emission from the individual pulse peaks is well described by a single-temperature hydrogen atmosphere spectrum, with the exception of PSR J0437-4715, for which multiple temperatures are required.

[32]  arXiv:1912.05707 [pdf, other]

Title: Constraining the Neutron Star Mass-Radius Relation and Dense Matter Equation of State with NICER. II. Emission from Hot Spots on a Rapidly Rotating Neutron Star

Authors: Slavko Bogdanov, Frederick K. Lamb, Simin Mahmoodifar, M. Coleman Miller, Sharon M. Morsink, Thomas E. Riley, Tod E. Strohmayer, Anna L. Watts, Alexander J. Dittmann, Deepto Chakrabarty, Sebastien Guillot, Zaven Arzoumanian, Keith C. Gendreau

Comments: 31 pages, 14 figures; accepted for publication in the Astrophysical Journal Letters

Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

We describe the model of surface emission from a rapidly rotating neutron star that is applied to Neutron Star Interior Composition Explorer X-ray data of millisecond pulsars in order to statistically constrain the neutron star mass-radius relation and dense matter equation of state. To ensure that the associated calculations are both accurate and precise, we conduct an extensive suite of verification tests between our numerical codes for both the Schwarzschild + Doppler and Oblate Schwarzschild approximations, and compare both approximations against exact numerical calculations. We find superb agreement between the code outputs, as well as in comparison against a set of analytical and semi-analytical calculations, which combined with their speed, demonstrates that the codes are well-suited for large-scale statistical sampling applications. A set of verified, high-precision reference synthetic pulse profiles is provided to the community to facilitate testing of other independently developed codes.

[33]  arXiv:1912.05708 [pdf, other]

Title: NICER X-ray Observations of Seven Nearby Rotation-Powered Millisecond Pulsars

Authors: S. Guillot, M. Kerr, P. S. Ray, S. Bogdanov, S. Ransom, J. S. Deneva, Z. Arzoumanian, P. Bult, D. Chakrabarty, K. C. Gendreau, W. C. G. Ho, G. K. Jaisawal, C. Malacaria, M. C. Miller, T. E. Strohmayer, M. T. Wolff, K. S. Wood, N. A. Webb, L. Guillemot, I. Cognard, G. Thereau

Comments: 25 pages, 11 tables, 4 figures. In press in The Astrophysical Journal Letters

Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

NICER observed several rotation-powered millisecond pulsars to search for or confirm the presence of X-ray pulsations. When broad and sine-like, these pulsations may indicate thermal emission from hot polar caps at the magnetic poles on the neutron star surface. We report confident detections ($\ge4.7\sigma$ after background filtering) of X-ray pulsations for five of the seven pulsars in our target sample: PSR J0614-3329, PSR J0636+5129, PSR J0751+1807, PSR J1012+5307, and PSR J2241-5236, while PSR J1552+5437 and PSR J1744-1134 remain undetected. Of those, only PSR J0751+1807 and PSR J1012+5307 had pulsations previously detected at the 1.7$\sigma$ and almost 3$\sigma$ confidence levels, respectively, in XMM-Newton data. All detected sources exhibit broad sine-like pulses, which are indicative of surface thermal radiation. As such, these MSPs are promising targets for future X-ray observations aimed at constraining the neutron star mass-radius relation and the dense matter equation of state using detailed pulse profile modeling. Furthermore, we find that three of the detected millisecond pulsars exhibit a significant phase offset between their X-ray and radio pulses.

[34]  arXiv:1912.05714 [pdf, ps, other]

Title: Estimating the temperature and density of a spicule from 100 GHz data obtained with ALMA

Authors: Masumi Shimojo, Tomoko Kawate, Takenori J. Okamoto, Takaaki Yokoyama, Noriyuki Narukage, Taro Sakao, Kazumasa Iwai, Gregory D. Fleishman, Kazunari Shibata

Comments: 8 pages, 4 figures, Accepted to ApJL

Subjects: Solar and Stellar Astrophysics (astro-ph.SR)

We succeeded in observing two large spicules simultaneously with the Atacama Large Millimeter/submillimeter Array (ALMA), the Interface Region Imaging Spectrograph (IRIS), and the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory. One is a spicule seen in the IRIS Mg II slit-jaw images and AIA 304\AA\ images (MgII/304A spicule). The other one is a spicule seen in the 100GHz images obtained with ALMA (100GHz spicule). Although the 100GHz spicule overlapped with the MgII/304A spicule in the early phase, it did not show any corresponding structures in the IRIS Mg II and AIA 304A images after the early phase. It suggests that the spicules are individual events and do not have a physical relationship. To obtain the physical parameters of the 100GHz spicule, we estimate the optical depths as a function of temperature and density using two different methods. One is using the observed brightness temperature by assuming a filling factor, and the other is using an emission model for the optical depth. As a result of comparing them, the kinetic temperature of the plasma and the number density of ionized hydrogens in the 100GHz spicule are ~6800 K and 2.2 x 10^10 cm^-3. The estimated values can explain the absorbing structure in the 193A image, which appear as a counterpart of the 100GHz spicule. These results suggest that the 100GHz spicule presented in this paper is classified to a macrospicule without a hot sheath in former terminology.

[35]  arXiv:1912.05749 [pdf, ps, other]

Title: Do the TRAPPIST-1 Planets Have Hydrogen-rich Atmospheres?

Authors: Yasunori Hori, Masahiro Ogihara

Comments: 10 pages, 3 figures, accepted for publication in ApJ

Subjects: Earth and Planetary Astrophysics (astro-ph.EP)

Recently, transmission spectroscopy in the atmospheres of the TRAPPIST-1 planets revealed flat and featureless absorption spectra, which rule out cloud-free hydrogen-dominated atmospheres. Earth-sized planets orbiting TRAPPIST-1 likely have either a clear or a cloudy/hazy hydrogen-poor atmosphere. In this paper, we investigate whether a proposed formation scenario is consistent with expected atmospheric compositions of the TRAPPIST-1 planets. We examine the amount of a hydrogen-rich gas that TRAPPIST-1-like planets accreted from the ambient disk until disk dispersal. Since TRAPPIST-1 planets are trapped into a resonant chain, we simulate disk gas accretion onto a migrating TRAPPIST-1-like planet. We find that the amount of an accreted hydrogen-rich gas is as small as 10$^{-2}$ wt% and 0.1 wt% for TRAPPIST-1b and 1c, 10$^{-2}$ wt% for 1d, 1 wt% for 1e, a few wt% for 1f and 1g and 1 wt% for 1h, respectively. We also calculate a long-term thermal evolution of TRAPPIST-1-like planets after disk dissipation and estimate the mass loss of their hydrogen-rich atmospheres driven by a stellar X-ray and UV irradiation. We find that all the accreted hydrogen-rich atmospheres can be lost via hydrodynamic escape. Therefore, we conclude that TRAPPIST-1 planets should have no primordial hydrogen-rich gases but secondary atmospheres such as a Venus-like one and water vapor, if they currently retain atmospheres.

[36]  arXiv:1912.05762 [pdf, ps, other]

Title: A systematic study of the advection-dominated accretion flow for the origin of the X-ray emission in weakly magnetized low-level accreting neutron star

Authors: Erlin Qiao, B.F. Liu

Comments: 13 pages, 23 figures. Accepted for publication by MNRAS

Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

Observationally, the X-ray spectrum ($0.5-10$ keV) of low-level accreting neutron stars (NSs) can generally be well fitted by the model with two components, i.e, a thermal soft X-ray component plus a power-law component. Meanwhile, the fractional contribution of the power-law luminosity $\eta$ ($\eta\equiv L^{\rm power\ law}_{\rm 0.5-10\rm keV}/L_{\rm 0.5-10\rm keV}$) varies with the X-ray luminosity $L_{\rm 0.5-10\rm keV}$. In this paper, we systematically investigate the origin of such X-ray emission within the framework of the advection-dominated accretion flow (ADAF) around a weakly magnetized NS, in which the thermal soft X-ray component arises from the surface of the NS and the power-law component arises from the ADAF itself. We test the effects of the viscosity parameter $\alpha$ in the ADAF and thermalized parameter $f_{\rm th}$ (describing the fraction of the ADAF energy released at the surface of the NS as thermal emission) on the relation of $\eta$ versus $L_{\rm 0.5-10\rm keV}$. It is found that $\eta$ is nearly a constant ($\sim$ zero) with $L_{\rm 0.5-10\rm keV}$ for different $\alpha$ with $f_{\rm th}=1$, which is inconsistent with observations. Meanwhile, it is found that a change of $f_{\rm th}$ can significantly change the relation of $\eta$ versus $L_{\rm 0.5-10\rm keV}$. By comparing with a sample of non-pulsating NS-LMXBs probably dominated by low-level accretion onto NSs, it is found that a small value of $f_{\rm th} \lesssim 0.1$ is needed to match the observed range of $\eta \gtrsim 10\%$ in the diagram of $\eta$ versus $L_{\rm 0.5-10\rm keV}$. Finally, we argue that the small value of $f_{\rm th} \lesssim 0.1$ implies that the radiative efficiency of NSs with an ADAF accretion may not be as high as the predicted result previously of $\epsilon \sim {\dot M GM\over R_{*}}/{\dot M c^2}\sim 0.2$ despite the existence of the hard surface.

[37]  arXiv:1912.05764 [pdf, ps, other]

Title: Multi-Messenger Connections among High-Energy Cosmic Particles

Authors: Kohta Murase

Comments: 9 pages, 5 figures, based on Proceedings of the 36th International Cosmic Ray Conference (ICRC 2019), July 24-August 1, 2019, Madison, USA. Texts and Figure 5 modified

Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

The origin of high-energy cosmic neutrinos is one of the biggest mysteries in astroparticle physics. The fact that diffuse intensities of high-energy neutrinos, ultrahigh-energy cosmic rays, and GeV-TeV gamma rays are all comparable suggests that these messengers are physically connected. The IceCube data above 100 TeV energies can be naturally explained by cosmic-ray reservoir models. In particular, starburst galaxies and galaxy clusters/groups serve as natural storage rooms of cosmic rays, and it has been theoretically predicted that these sources are promising sites of high-energy neutrinos and gamma rays that are produced via inelastic pp interactions. Indeed, the predictions made before the discovery of IceCube neutrinos are consistent with the current high-energy neutrino data measured in IceCube, and that they could give a grand-unified view of sub-PeV neutrinos, sub-TeV gamma rays, and ultrahigh-energy cosmic rays. These unified models have strong prediction powers, which can be tested by next-generation neutrino detectors such as IceCube-Gen2 as well as gamma-ray telescopes such as CTA. The recent observations have also shown that the 10-100 TeV diffuse neutrino flux is higher than that at PeV energies, which suggests that they come from a different class of neutrino sources. The detailed comparison with the diffuse isotropic gamma-ray background measured by Fermi has revealed that these medium-energy neutrinos are likely to come from hidden cosmic-ray accelerators, from which neutrinos can escape while GeV-TeV gamma rays are attenuated. The candidate source classes are choked gamma-ray burst jets and active galactic nuclei (AGN) cores. In particular, the AGN corona model predicts a unique connection between 10-100 TeV neutrinos and MeV gamma rays, which can be robustly tested with future MeV gamma-ray missions such as AMEGO.

[38]  arXiv:1912.05813 [pdf, other]

Title: SOFIA/HAWC+ View of an Extremely Luminous Infrared Galaxy, WISE1013+6112

Authors: Yoshiki Toba, Wei-Hao Wang, Tohru Nagao, Yoshihiro Ueda, Junko Ueda, Chen-Fatt Lim, Yu-Yen Chang, Toshiki Saito, Ryohei Kawabe

Comments: 9 pages, 4 figures, and 2 tables, accepted for publication in ApJ

Subjects: Astrophysics of Galaxies (astro-ph.GA)

We present far-infrared (FIR) properties of an extremely luminous infrared galaxy (ELIRG) at $z_{\rm spec}$ = 3.703, WISE J101326.25+611220.1 (WISE1013+6112). This ELIRG is selected as an IR-bright dust-obscured galaxy (DOG) based on the photometry from the Sloan digital sky survey (SDSS) and wide-field infrared survey explorer (WISE). In order to derive its accurate IR luminosity, we perform follow-up observations at 89 and 154 $\mu$m using the high-resolution airborne wideband camera-plus (HAWC+) on board the 2.7-m stratospheric observatory for infrared astronomy (SOFIA) telescope. We conduct spectral energy distribution (SED) fitting with CIGALE using 15 photometric data (0.4-1300 $\mu$m). We successfully pin down FIR SED of WISE1013+6112 and its IR luminosity is estimated to be $L_{\rm IR}$ = (1.62 $\pm$ 0.08) $\times 10^{14}$ $L_{\odot}$, making it one of the most luminous IR galaxies in the universe. We determine the dust temperature of WISE1013+6112 is $T_{\rm dust}$ = 89 $\pm$ 3 K, which is significantly higher than that of other populations such as SMGs and FIR-selected galaxies at similar IR luminosities. The resultant dust mass is $M_{\rm dust}$ = (2.2 $\pm$ 0.1) $\times 10^{8}$ $M_{\odot}$. This indicates that WISE1013+6112 has a significant active galactic nucleus (AGN) and star-forming activity behind a large amount of dust.

[39]  arXiv:1912.05834 [pdf, other]

Title: The imperative to reduce carbon emissions in astronomy

Authors: Adam R. H. Stevens, Sabine Bellstedt, Pascal J. Elahi, Michael T. Murphy

Comments: White paper for the Decadal plan for Australian astronomy 2016-2025: Mid-term review. 7 pages (6 excl. references), 1 figure

Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Cosmology and Nongalactic Astrophysics (astro-ph.CO); Earth and Planetary Astrophysics (astro-ph.EP); Astrophysics of Galaxies (astro-ph.GA); High Energy Astrophysical Phenomena (astro-ph.HE)

Just as in any other profession, astronomers have an obligation to reduce their carbon footprint to meet the necessary global requirements for limiting the effects of climate change. In this white paper, we estimate that Australian astronomers' total greenhouse gas emissions from their regular work activities are >~15 ktCO_2-e/yr (equivalent kilotonnes of carbon dioxide per year). This can be broken into 4.3 +/- 1.1 ktCO_2-e/yr from flights, ~6.8 ktCO_2-e/yr from supercomputer usage, ~1.8 ktCO_2-e/yr from powering office buildings, and ~2 ktCO_2-e/yr from the operation of the Murchison Radio Observatory (with other observatories unaccounted for here that would add to this number). Split across faculty scientists, postdoctoral researchers, and PhD students, this averages to >~19 tCO_2-e/yr per astronomer. We outline steps astronomers can take to reduce their emissions from these environmentally unsustainable practices. (1) We should exclusively use supercomputers and observatories that are powered predominantly by renewable energy sources. Where facilities that we currently use are unsatisfactory, they should be lobbied to invest in renewables, such as solar or wind farms. Emphasis must also be placed on code efficiency for projects that consume millions of CPU core-hours. (2) Air travel should be reduced wherever possible, replaced primarily by video conferencing. We emphasise that while carbon offsetting should be mandatory for all 'unavoidable' travel, it does not negate carbon emissions, and hence does not justify flights. Based on an ICRAR-UWA case study, senior scientists have the greatest responsibility to reduce flying, as they generate ~70% more emissions per person from flying than postdocs, and more than triple that of PhD students, on average. (3) A sustainability chapter and award should be established by the Astronomical Society of Australia.

[40]  arXiv:1912.05857 [pdf, other]

Title: Metal abundances in the MACER simulations of the hot interstellar medium

Authors: S. Pellegrini (1), Z. Gan (2,3), J.P. Ostriker (2), L. Ciotti (1) ((1) Dept. of Physics and Astronomy, University of Bologna, (2) Dept. of Astronomy, Columbia University, (3) Shanghai Astronomical Observatory)

Comments: 6 pages, 5 figures, Proceedings of the XMM-Newton 2019 science workshop "Astrophysics of hot plasma in extended X-ray sources", to be published in Astron. Nachr

Subjects: Astrophysics of Galaxies (astro-ph.GA); High Energy Astrophysical Phenomena (astro-ph.HE)

A hot plasma is the dominant phase of the interstellar medium of early-type galaxies. Its origin can reside in stellar mass losses, residual gas from the formation epoch, and accretion from outside of the galaxies. Its evolution is linked to the dynamical structure of the host galaxy, to the supernova and AGN feedback, and to (late-epoch) star formation, in a way that has yet to be fully understood. Important clues about the origin and evolution of the hot gas come from the abundances of heavy metals, that have been studied with increasing detail with XMM-Newton and Chandra. We present recent high resolution hydrodynamical simulations of the hot gas evolution that include the above processes, and where several chemical species, originating in AGB stars and supernovae of type Ia and II, have also been considered. The high resolution, of few parsecs in the central galactic region, allows us to track the metal enrichment, transportation and dilution throughout the galaxy. The comparison of model results with observed abundances reveals a good agreement for the region enriched by the AGN wind, but also discrepancies for the diffuse hot gas; the latter indicate the need for a revision of standard assumptions, and/or the importance of neglected effects as those due to the dust, and/or residual uncertainties in deriving abundances from the X-ray spectra.

[41]  arXiv:1912.05860 [pdf]

Title: Infrared counterparts of X-ray galaxies

Authors: A. Tugay, S. Shevchenko

Comments: 8 pages, 5 figures

Journal-ref: Odessa Astronomical Publications, 2019, Vol. 32, pp. 42-45

Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)

Population studies of the extragalactic objects are a major part of the universe large-scale structure study. Apart from radio, infrared, and visible wavelength bands, observations and further identification of extragalactic objects such as galaxies, quasars, blazers, liners, and active star burst regions are also conducted in the X-ray and gamma bands. In this paper we make identification and cross-correlate of the infrared and X-ray observational data, build a distribution of a selected sample sources by types and attempted to analyze types of the extragalactic objects at distances up to z = 0.1 using observational data of relevant space observatories.
Data from a leading X-ray space observatory XMM-Newton were used to compile the largest catalog of X-ray sources. Current version of XMM SSC (Serendipitous Source Catalog) contains more than half a million sources. In our previous works we selected and analyzed a sample of 5021 X-ray galaxies observed by XMM-Newton. Identification and classification of these sources is essential next step of the study. In this study we used infrared apparent magnitudes from WISE catalog of AGN candidates. In 2010 space telescope WISE performed full sky survey in four infrared bands and detected 747 million sources. WISE catalog of AGN candidates amounts 4 million of possible extragalactic sources. We built infrared color-color diagram for our sample of X-ray galaxies and assessed their types using WISE telescope data. In this study we also analyzed large scale structure of the universe (distances up to z=0.1). This analysis revealed Coma galaxy cluster and SDSS Sloan Great Wall. In the further studies we are planning to investigate the distribution of different types of X-ray galaxies within the large-scale structures of the Universe.

[42]  arXiv:1912.05863 [pdf, other]

Title: Accretion and star formation in 'radio-quiet' quasars

Authors: Sarah V. White, Matt J. Jarvis, Eleni Kalfountzou, Martin J. Hardcastle, Aprajita Verma, Jose M. Cao Orjales, Jason Stevens

Comments: 5 pages, 2 figures, proceedings of IAU Symposium 356 on "Nuclear Activity in Galaxies Across Cosmic Time", October 2019

Subjects: Astrophysics of Galaxies (astro-ph.GA)

Radio observations allow us to identify a wide range of active galactic nuclei (AGN), which play a significant role in the evolution of galaxies. Amongst AGN at low radio-luminosities is the 'radio-quiet' quasar (RQQ) population, but how they contribute to the total radio emission is under debate, with previous studies arguing that it is predominantly through star formation. In this talk, SVW summarised the results of recent papers on RQQs, including the use of far-infrared data to disentangle the radio emission from the AGN and that from star formation. This provides evidence that black-hole accretion, instead, dominates the radio emission in RQQs. In addition, we find that this accretion-related emission is correlated with the optical luminosity of the quasar, whilst a weaker luminosity-dependence is evident for the radio emission connected with star formation. What remains unclear is the process by which this accretion-related emission is produced. Understanding this for RQQs will then allow us to investigate how this type of AGN influences its surroundings. Such studies have important implications for modelling AGN feedback, and for determining the accretion and star-formation histories of the Universe.

[43]  arXiv:1912.05868 [pdf, other]

Title: H.E.S.S. and Fermi-LAT observations of PSR B1259-63/LS 2883 during its 2014 and 2017 periastron passages

Authors: H.E.S.S. Collaboration, H. Abdalla, R. Adam, F. Aharonian, F. Ait Benkhali, E.O. Angüner, M. Arakawa, C. Arcaro, C. Armand, H. Ashkar, M. Backes, V. Barbosa Martins, M. Barnard, Y. Becherini, D. Berge, K. Bernlöhr, R. Blackwell, M. Böttcher, C. Boisson, J. Bolmont, S. Bonnefoy, J. Bregeon, M. Breuhaus, F. Brun, P. Brun, M. Bryan, M. Büchele, T. Bulik, T. Bylund, S. Caroff, A. Carosi, S. Casanova, M. Cerruti, T. Chand, S. Chandra, R.C.G. Chaves, A. Chen, S. Colafrancesco, M. Curyło, I.D. Davids, C. Deil, J. Devin, P. deWilt, L. Dirson, A. Djannati-Ataï, A. Dmytriiev, A. Donath, V. Doroshenko, J. Dyks, K. Egberts, G. Emery, J.-P. Ernenwein, S. Eschbach, K. Feijen, S. Fegan, A. Fiasson, G. Fontaine, S. Funk, M. Füßling, S. Gabici, Y.A. Gallant, F. Gaté, et al. (164 additional authors not shown)

Comments: 16 pages, 7 figures Accepted for publication in A&A

Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

PSR B1259-63/LS 2883 is a gamma-ray binary system consisting of a pulsar in an eccentric orbit around a bright Oe stellar-type companion star that features a dense circumstellar disc. The high- and very-high-energy (HE, VHE) gamma-ray emission from PSR B1259-63/LS 2883 around the times of its periastron passage are characterised, in particular, at the time of the HE gamma-ray flares reported to have occurred in 2011, 2014, and 2017. Spectra and light curves were derived from observations conducted with the H.E.S.S.-II array in 2014 and 2017.
A local double-peak profile with asymmetric peaks in the VHE light curve is measured, with a flux minimum at the time of periastron $t_p$ and two peaks coinciding with the times at which the neutron star crosses the companion's circumstellar disc ($\sim t_p \pm 16$ d). A high VHE gamma-ray flux is also observed at the times of the HE gamma-ray flares ($\sim t_p + 30$ d) and at phases before the first disc crossing ($\sim t_p - 35$ d). PSR B1259-63/LS 2883 displays periodic flux variability at VHE gamma-rays without clear signatures of super-orbital modulation in the time span covered by H.E.S.S. observations. In contrast, the photon index of the measured power-law spectra remains unchanged within uncertainties for about 200 d around periastron. Lower limits on exponential cut-off energies up to $\sim 40$ TeV are placed.
At HE gamma-rays, PSR B1259-63/LS 2883 has now been detected also before and after periastron, close to the disc crossing times. Repetitive flares with distinct variability patterns are detected in this energy range. Such outbursts are not observed at VHEs, although a relatively high emission level is measured. The spectra obtained in both energy regimes displays a similar slope, although a common physical origin either in terms of a related particle population, emission mechanism, or emitter location is ruled out.

[44]  arXiv:1912.05883 [pdf, ps, other]

Title: RASCAL: Towards automated spectral wavelength calibration

Authors: Josh Veitch-Michaelis, Marco C Lam

Comments: 4 pages, 2 figures, 29th Astronomical Data Analysis Software & Systems (ADASS) conference

Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)

Wavelength calibration is a routine and critical part of any spectral work-flow, but many astronomers still resort to matching detected peaks and emission lines by hand. We present RASCAL (RANSAC Assisted Spectral CALibration), a python library for automated wavelength calibration of astronomical spectrographs. RASCAL implements recent state-of-the-art methods for wavelength calibration and requires minimal input from a user. In this paper we discuss the implementation of the library and apply it to real-world calibration spectra.

[45]  arXiv:1912.05884 [pdf, other]

Title: Hot Super-Earths with Hydrogen Atmospheres: A Model Explaining Their Paradoxical Existence

Authors: Darius Modirrousta-Galian, Daniele Locci, Giovanna Tinetti, Giuseppina Micela

Comments: 20 pages, 15 figures

Subjects: Earth and Planetary Astrophysics (astro-ph.EP)

In this paper we propose a new mechanism that could explain the survival of hydrogen atmospheres on some hot super-Earths. We argue that on close-orbiting tidally-locked super-Earths the tidal forces with the orbital and rotational centrifugal forces can partially confine the atmosphere on the nightside. Assuming a super terran body with an atmosphere dominated by volcanic species and a large hydrogen component, the heavier molecules can be shown to be confined within latitudes of $\lesssim 80^{\circ}$ whilst the volatile hydrogen is not. Because of this disparity the hydrogen has to slowly diffuse out into the dayside where XUV irradiation destroys it. For this mechanism to take effect it is necessary for the exoplanet to become tidally locked before losing the totality of its hydrogen envelop. Consequently, for super-Earths with this proposed configuration it is possible to solve the tidal-locking and mass-loss timescales in order to constrain their formation `birth' masses. Our model predicts that 55 Cancri e formed with a day-length between approximately $17-18.5$ hours and an initial mass less than $\rm \sim12 M_{\oplus}$ hence allowing it to become tidally locked before the complete destruction of its atmosphere. For comparison, CoRoT-7b, an exoplanet with very similar properties to 55 Cancri e but lacking an atmosphere, formed with a day-length significantly different from $\sim 20.5$ hours whilst also having an initial mass smaller than $\rm \sim9 M_{\oplus}$

[46]  arXiv:1912.05885 [pdf, ps, other]

Title: Automated SpectroPhotometric Image REDuction (ASPIRED)

Authors: Marco C Lam, Robert J Smith, Iain A Steele

Comments: 4 pages, 1 figure, 29th Astronomical Data Analysis Software & Systems (ADASS) conference

Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)

We aim to provide a suite of publicly available spectral data reduction software to facilitate rapid scientific outcomes from time-domain observations. For time resolved observations, an automated pipeline frees astronomers from performance of the routine data analysis tasks to concentrate on interpretation, planning future observations and communication with international collaborators. The project consists of two parts: data processing (ASPIRED) and a graphical user interface (gASPIRED).ASPIREDis written in python 3, and was intentionally developed as a self-consistent reduction pipeline with its own diagnostics and error handling. The pipeline can reduce2D spectral data from raw image to wavelength and flux calibrated 1D spectrum automatically without any user input.gASPIREDis a cross-platform software developedwithElectronon a single code base. It brings interactivity to the software with a well-maintained and user-friendly environment.

[47]  arXiv:1912.05889 [pdf, other]

Title: HST/STIS capability for Love number measurement of WASP-121b

Authors: Hugo Hellard, Szilárd Csizmadia, Sebastiano Padovan, Frank Sohl, Heike Rauer

Comments: Accepted for publication in ApJ

Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)

Data from transit light curves, radial velocity and transit timing observations can be used to probe the interiors of exoplanets beyond the mean density, by measuring the Love numbers $h_2$ and $k_2$. The first indirect estimate of $k_2$ for an exoplanet from radial velocity and transit timing variations observations has been performed by taking advantage of the years-spanning baseline. Not a single measurement of $h_2$ has been achieved from transit light curves, mostly because the photometric precision of current observing facilities is still too low. We show that the Imaging Spectrograph instrument on-board the Hubble Space Telescope could measure $h_2$ of the hot Jupiter WASP-121b if only few more observations were gathered. We show that a careful treatment of the noise and stellar limb darkening must be carried out to achieve a measurement of $h_2$. In particular, we find that the impact of the noise modelling on the estimation of $h_2$ is stronger than the impact of the limb darkening modelling. In addition, we emphasize that the wavelet method for correlated noise analysis can mask limb brightening. Finally, using presently available data, we briefly discuss the tentative measurement of $h_2 = 1.39^{+0.71}_{-0.81}$ in terms of interior structure. Additional observations would further constrain the interior of WASP-121b and possibly provide insights on the physics of inflation. The possibility of using the approach presented here with the Hubble Space Telescope provides a bridge before the high-quality data to be returned by the James Webb Space Telescope and PLATO telescope in the coming decade.

[48]  arXiv:1912.05894 [pdf, other]

Title: A Mini-Imaging Air Cherenkov Telescope

Authors: S. Njoh Ekoume, C. Alispach, F. Cadoux, V. Coco, D. della Volpe, Y. Favre, M. Heller, T. Montaruli, A. Nagai, A. Neronov, Y. Renier, I. Troyano

Comments: submitted to JINST

Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)

In this paper we describe the different software and hardware elements of a mini-telescope for the detection of cosmic rays and gamma-rays using the Cherenkov light emitted by their induced particle showers in the atmosphere. We estimate the physics reach of the standalone mini-telescope and present some results of the measurements done at the Sauverny Observatory of the University of Geneva and at the Saint-Luc Observatory, which demonstrate the ability of the telescope to observe cosmic rays with energy above about 100 TeV. Such a mini-telescope can constitute a cost-effective out-trigger array that can surround other gamma-ray telescopes or extended air showers detector arrays. Its development was born out of the desire to illustrate to students and amateurs the cosmic ray and gamma-ray detection from ground, as an example of what is done in experiments using larger telescopes. As a matter of fact, a mini-telescope can be used in outreach night events. While outreach is becoming more and more important in the scientific community to raise interest in the general public, the realisation of the mini-telescope is also a powerful way to train students on instrumentation such as photosensors, their associated electronics, acquisition software and data taking. In particular, this mini-telescope uses silicon photomultipliers (SiPM) and the dedicated ASIC, CITIROC.

[49]  arXiv:1912.05926 [pdf, other]

Title: Cosmological constraints on ultra-light axion fields

Authors: Jiangang Kang, Yan Gong, Gong Cheng, Xuelei Chen

Comments: 10 pages, 4 figures, 5 tables. Accepted by Research in Astronomy and Astrophysics

Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)

Ultra-light axions (ULAs) with mass less than 10^-20 eV have interesting behaviors that may contribute to either dark energy or dark matter at different epochs of the Universe. Its properties can be explored by cosmological observations, such as expansion history of the Universe, cosmic large-scale structure, cosmic microwave background, etc. In this work, we study the ULAs with a mass around 10^-33 eV, which means the ULA field still rolls slowly at present with the equation of state w=-1 as dark energy. In order to investigate the mass and other properties of this kind of ULA field, we adopt the measurements of Type Ia supernova (SN Ia), baryon acoustic oscillation (BAO), and Hubble parameter H(z). The Markov Chain Monte Carlo (MCMC) technique is employed to perform the constraints on the parameters. Finally, by exploring four cases of the model, we find that the mass of this ULA field is about 3x10^-33 eV if assuming the initial axion field phi_i=M_pl. We also investigate a general case by assuming phi_i< M_pl and find that the fitting results of phi_i/M_pl are consistent with or close to 1 for the datasets we use.

[50]  arXiv:1912.05927 [pdf, other]

Title: Scalar induced gravitational waves in inflation with gravitationally enhanced friction

Authors: Chengjie Fu, Puxun Wu, Hongwei Yu

Comments: 15 pages, 5 figures, 1 table

Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)

We study the scalar induced gravitational wave (GW) background in inflation with gravitationally enhanced friction (GEF). The GEF mechanism, which is realized by assuming a nonminimal derivative coupling between the inflaton field and gravity, is used to amplify the small-scale curvature perturbations to generate a sizable amount of primordial black holes. We find that the GW energy spectra can reach the detectable scopes of the future GW projects, and the power spectrum of curvature perturbations has a power-law form in the vicinity of the peak. The scaling of the GW spectrum in the ultraviolet regions is two times that of the power spectrum slope, and has a lower bound. In the infrared regions, the slope of the GW spectrum can be described roughly by a log-dependent form. These features of the GW spectrum may be used to check the GEF mechanism if the scalar induced GWs are detected in the future.

[51]  arXiv:1912.05953 [pdf, other]

Title: Through Andromeda and Beyond: AGN Optical Transient 'Sharov21' Revisited

Authors: A. Bruce, A. Lawrence, D. McLeod, Nicholas P. Ross

Comments: 14 pages, 13 figures

Subjects: Astrophysics of Galaxies (astro-ph.GA)

We revisit a notable AGN known as `Sharov21', seen to undergo a dramatic outburst in 1992, brightening by a factor of thirty over a period of approximately one year. A simple microlensing model fit to the event lightcurve provides a constraint on the distance of the lensing object which is consistent with the distance to M31, strongly suggesting that this is the correct explanation. Archival XMM/Hubble/Spitzer data show that this AGN can be considered an otherwise unremarkable type-I AGN. Our analysis of the expected rate of background AGN being microlensed by a factor of two or more due to stellar-mass objects in M31 shows that events of this nature should only occur on average every half century. It is thus perhaps surprising that we have uncovered evidence for two more events that are qualitatively similar. A systematic search for new and archival events, with follow-up spectroscopy, is thus warranted.

[52]  arXiv:1912.05969 [pdf, ps, other]

Title: The Dearth of Difference between Central and Satellite Galaxies III. Environmental Dependence of Mass-Size and Mass-Structure Relations

Authors: Enci Wang, Huiyuan Wang, Houjun Mo, Frank C. van den Bosch, Xiaohu Yang

Comments: 21 pages, 15 figures. To appear in ApJ

Subjects: Astrophysics of Galaxies (astro-ph.GA)

As demonstrated in Paper I, the quenching properties of central and satellite galaxies are quite similar as long as both stellar mass and halo mass are controlled. Here we extend the analysis to the size and bulge-to-total light ratio (B/T) of galaxies. In general central galaxies have size-stellar mass and B/T-stellar mass relations different from satellites. However, the differences are eliminated when halo mass is controlled. We also study the dependence of size and B/T on halo-centric distance and find a transitional stellar mass (M$_{*,t}$) at given halo mass (M$_h$), which is about one fifth of the mass of the central galaxies in halos of mass M$_h$. The transitional stellar masses for size, B/T and quenched fraction are similar over the whole halo mass range, suggesting a connection between the quenching of star formation and the structural evolution of galaxies. Our analysis further suggests that the classification based on the transitional stellar mass is more fundamental than the central-satellite dichotomy, and provide a more reliable way to understand the environmental effects on galaxy properties. We compare the observational results with the hydro-dynamical simulation, EAGLE and the semi-analytic model, L-GALAXIES. The EAGLE simulation successfully reproduces the similarities of size for centrals and satellites and even M$_{*,t}$, while L-GALAXIES fails to recover the observational results.

[53]  arXiv:1912.05976 [pdf, ps, other]

Title: Toward accurate measurement of property-dependent galaxy clustering I. Comparison of the Vmax method and the "shuffled" method

Authors: Lei Yang (SJTU), Yipeng Jing, Zhigang Li, Xiaohu Yang

Comments: 15 pages, 7 figures, accepted to RAA

Journal-ref: RAA-2019-0333

Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)

Galaxy clustering provides insightful clues to our understanding of galaxy formation and evolution, as well as the universe. The redshift assignment for the random sample is one of the key steps to measure the galaxy clustering accurately. In this paper, by virtue of the mock galaxy catalogs, we investigate the effect of two redshift assignment methods on the measurement of galaxy two-point correlation functions (hereafter 2PCFs), the Vmax method and the "shuffled" method. We found that the shuffled method significantly underestimates both of the projected 2PCFs and the two-dimensional 2PCFs in redshift space. While the Vmax method does not show any notable bias on the 2PCFs for volume-limited samples. For flux-limited samples, the bias produced by the Vmax method is less than half of the shuffled method on large scales. Therefore, we strongly recommend the Vmax method to assign redshifts to random samples in the future galaxy clustering analysis.

[54]  arXiv:1912.05980 [pdf, other]

Title: 3D numerical study of an anisotropic heat transfer in outer layers of magnetized neutron stars

Authors: I. A. Kondratyev, S. G. Moiseenko, G. S. Bisnovatyi-Kogan, M. V. Glushikhina

Comments: Proceedings paper from "High Energy Phenomena in Relativistic Outflows VII" (HEPRO7, 9-12 July 2019, Facultat de Fisica, Universitat de Barcelona, Spain), accepted by Proceedings of Science (PoS)

Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

Periodic changes in a thermal soft X-ray flux of a rotating neutron star indicate a non-uniform distribution of the surface temperature. A possible cause of this phenomenon is a suppression of the heat flux across the magnetic field lines in a crust and an envelope of magnetized neutron stars. In this paper we study three-dimensional effects, associated with non-axisymmetric magnetic fields in neutron stars. We calculate the surface temperature distribution by solving numerically a three dimensional heat transfer equation in a magnetized neutron star crust. We adopt an anisotropic (tensorial) electron thermal conductivity coefficient, which is derived as an analytical solution of the Boltzmann equation with a Chapman-Enskog method. To calculate the surface temperature distribution, we construct a local one-dimensional plane-parallel model ("Ts-Tb"-relationship) of a magnetized neutron star envelope. We then use it as an outer boundary condition for the three-dimensional problem in the crust to find the self-consistent solution. To study possible observational manifestations from anisotropic temperature distributions we calculate light curves with a composite black-body model. Our calculations show, that a non-axisymmetric magnetic field distribution can lead to the irregular non-sinusoidal shape of a pulse profile as well as in some cases a significant amplification of pulsations of the thermal flux in comparison to the pure-dipolar magnetic field configurations.

[55]  arXiv:1912.05986 [pdf, other]

Title: LSQ13ddu: A rapidly-evolving stripped-envelope supernova with early circumstellar interaction signatures

Authors: Peter Clark, Kate Maguire, Cosimo Inserra, Simon Prentice, Stephen J. Smartt, Carlos Contreras, Griffin Hossenizadeh, Eric Y. Hsiao, Erkki Kankare, Mansi Kasliwal, Peter Nugent, Melissa Shahbandeh, Charles Baltay, David Rabinowitz, Iair Arcavi, Chris Ashall, Christopher R. Burns, Emma Callis, Ting-Wan Chen, Tiara Diamond, Morgan Fraser, D. Andrew Howell, Emir Karamehmetoglu, Rubina Kotak, Joseph Lyman, Nidia Morrell, Mark Phillips, Giuliano Pignata, Miika Pursiainen, Jesper Sollerman, Maximilian Stritzinger, Mark Sullivan, David Young

Comments: 22 pages, 20 figures, resubmitted to MNRAS after referee report

Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

This paper describes the rapidly evolving and unusual supernova LSQ13ddu, discovered by the La Silla-QUEST survey. LSQ13ddu displayed a rapid rise of just 4.8$\pm$0.9 d to reach a peak brightness of $-$19.70$\pm$0.02 mag in the $\mathit{LSQgr}$ band. Early spectra of LSQ13ddu showed the presence of narrow He I features arising from interaction with circumstellar material (CSM). These interaction signatures weakened quickly, with broad features consistent with those seen in stripped-envelope SNe becoming dominant around two weeks after maximum. The narrow He I velocities are consistent with wind velocities of luminous blue variables but its spectra lack the typically seen hydrogen features. The fast and bright early light curve is inconsistent with radioactive $^{56}$Ni powering but can be explained through a combination of CSM interaction and an underlying $^{56}$Ni decay component that dominates the later time behaviour of LSQ13ddu. Based on the strength of the underlying broad features, LSQ13ddu appears deficient in He compared to standard SNe Ib.

[56]  arXiv:1912.05995 [pdf, other]

Title: Extended radio emission associated with a breakout eruption from the back side of the Sun

Authors: D. E. Morosan, E. Palmerio, B. J. Lynch, E. K. J. Kilpua

Comments: 7 pages, 5 figures

Subjects: Solar and Stellar Astrophysics (astro-ph.SR)

Context. Coronal mass ejections (CMEs) on the Sun are the largest explosions in the Solar System that can drive powerful plasma shocks. The eruptions, shocks, and other processes associated to CMEs are efficient particle accelerators and the accelerated electrons in particular can produce radio bursts through the plasma emission mechanism. Aims. Coronal mass ejections and associated radio bursts have been well studied in cases where the CME originates close to the solar limb or within the frontside disc. Here, we study the radio emission associated with a CME eruption on the back side of the Sun on 22 July 2012. Methods. Using radio imaging from the Nan\c{c}ay Radioheliograph, spectroscopic data from the Nan\c{c}ay Decametric Array, and extreme-ultraviolet observations from the Solar Dynamics Observatory and Solar Terrestrial Relations Observatory spacecraft, we determine the nature of the observed radio emission as well as the location and propagation of the CME. Results. We show that the observed low-intensity radio emission corresponds to a type II radio burst or a short-duration type IV radio burst associated with a CME eruption due to breakout reconnection on the back side of the Sun, as suggested by the pre-eruptive magnetic field configuration. The radio emission consists of a large, extended structure, initially located ahead of the CME, that corresponds to various electron acceleration locations. Conclusions. The observations presented here are consistent with the breakout model of CME eruptions. The extended radio emission coincides with the location of the current sheet and quasi-separatrix boundary of the CME flux and the overlying helmet streamer and also with that of a large shock expected to form ahead of the CME in this configuration.

[57]  arXiv:1912.06002 [pdf, ps, other]

Title: Penumbral brightening events observed in AR NOAA 12546

Authors: M. Murabito, S. L. Guglielmino, I. Ermolli, M. Stangalini, F. Giorgi

Comments: 14 pages, accepted for ApJ; some figures are in B/W to accomplish size limits

Subjects: Solar and Stellar Astrophysics (astro-ph.SR)

Penumbral transient brightening events have been attributed to magnetic reconnection episodes occurring in the low corona. We investigated the trigger mechanism of these events in active region NOAA 12546 by using multi-wavelength observations obtained with the Interferometric Bidimensional Spectrometer (IBIS), by the \textit{Solar Dynamics Observatory} (SDO), the \textit{Interface Region Imaging Spectrograph} (IRIS), and the \textit{Hinode} satellites. We focused on the evolution of an area of the penumbra adjacent to two small-scale emerging flux regions (EFRs), which manifested three brightening events detected from the chromosphere to the corona. Two of these events correspond to B-class flares. The same region showed short-lived moving magnetic features (MMFs) that streamed out from the penumbra. In the photosphere, the EFRs led to small-scale penumbral changes associated with a counter-Evershed flow and to a reconfiguration of the magnetic fields in the moat. The brightening events had one of the footpoints embedded in the penumbra and seemed to result from the distinctive interplay between the pre-existing penumbral fields, MMFs, and the EFRs. The \textit{IRIS} spectra measured therein reveal enhanced temperature and asymmetries in spectral lines, suggestive of event triggering at different height in the atmosphere. Specifically, the blue asymmetry noted in \ion{C}{2} and \ion{Mg}{2} h\&k lines suggests the occurrence of chromospheric evaporation at the footpoint located in the penumbra as a consequence of magnetic reconnection process at higher atmospheric heigths.

[58]  arXiv:1912.06008 [pdf, other]

Title: Probing the mid-layer structure of red giants I. Mixed-mode coupling factor as a seismic diagnosis

Authors: C. Pinçon, M.-J. Goupil, K. Belkacem

Comments: 27 pages, accepted in A\&A

Subjects: Solar and Stellar Astrophysics (astro-ph.SR)

The space-borne missions CoRoT and Kepler have already brought stringent constraints on the internal structure of low-mass evolved stars, a large part of which results from the detection of mixed modes. However, all the potential of these oscillation modes as a diagnosis of the stellar interior has not been fully exploited yet. In particular, the coupling factor or the gravity-offset of mixed modes, $q$ and $\varepsilon_{\rm g}$, are expected to provide additional constraints on the mid-layers of red giants, which are located between the hydrogen-burning shell and the neighborhood of the base of the convective zone. In the present paper, we investigate the potential of the coupling factor in probing the mid-layer structure of evolved stars. Guided by typical stellar models and general physical considerations, we modeled the coupling region along with evolution. We subsequently obtained an analytical expression of $q$ based on the asymptotic theory of mixed modes and compared it to observations. We show that the value of $q$ is degenerate with respect to the thickness of the coupling evanescent region and the local density scale height. A structural interpretation of the global variations in $q$ observed on the subgiant and the red giant branches, as well as on the red clump, was obtained in the light of this model. We demonstrate that $q$ has the promising potential to probe the migration of the base of the convective region as well as convective extra-mixing in evolved red giant stars with typically $\nu_{\rm max} \lesssim 100~\mu$Hz. We also show that the frequency-dependence of $q$ cannot be neglected in the oscillation spectra of such stars, which is in contrast with what is assumed in the current measurement methods. This analytical study paves the way for a more quantitative exploration of the link of $q$ with the internal properties of evolved stars using stellar models.

[59]  arXiv:1912.06022 [pdf, other]

Title: On the formation of exotic, massive, stellar-remnant black holes at solar and sub-solar metallicities through evolution of massive binaries

Authors: Sambaran Banerjee

Comments: 11 pages, 4 figures, 1 appendix. Submitted to MNRAS. Comments are welcome

Subjects: Solar and Stellar Astrophysics (astro-ph.SR); High Energy Astrophysical Phenomena (astro-ph.HE)

The recent inference of a 70M_sun black hole (BH) in the Galactic, detached binary LB-1 has sparked cross-disciplinary debate since a stellar remnant of such large mass is well above what can be expected from stellar-evolutionary theory, especially in an enriched environment like that of the Milky Way. This study focusses on the possibilities of formation of extraordinarily massive BHs at solar and globular cluster (GC)-like metallicities via evolution of massive stellar binaries. A population-synthesis approach is followed utilizing the recently updated BSE program. BHs in the mass range of 50M_sun-80M_sun could be formed at the solar metallicity only if a large fraction, >70%, of matter is allowed to accrete onto a low-mass BH, in a BH-star merger product (a "black hole Thorne-Zytkow object"; BH-TZO). Their counterparts at GC-like metallicities can reach 100 M_sun. Although post-accretion BHs can, generally, be expected to be of high spin parameter, they can potentially be of low spin in the case of a BH-TZO. This spin aspect remains speculative in this work and deserves detailed hydrodynamic studies.

[60]  arXiv:1912.06050 [pdf, other]

Title: Mimetic DBI Inflation in Confrontation with Planck2018 data

Authors: Kourosh Nozari, Narges Rashidi

Comments: 45 pages, 17 figures, 13 tables

Journal-ref: The Astrophysical Journal, 882 (2019) 78

Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)

We study mimetic gravity in the presence of a DBI-like term which is a non-canonical setup of the scalar field's derivatives. We consider two general cases with varying and constant sound speeds and construct the potentials for both the DBI and Mimetic DBI models. By considering the power-law scale factor as $a=a_{0}\,t^{n}$, we seek for the observational viability of these models. We show that, the Mimetic DBI model in some ranges of the parameters space is free of ghost and gradient instabilities. By studying $r-n_{s}$ and $\alpha_{s}-n_{s}$ behavior in confrontation with Planck2018 data, we find some constraints on the model's parameters. We show that for the case with varying sound speed, although power-law DBI inflation is not consistent with Planck2018 TT, TE, EE+low E+lensing data, but the Mimetic DBI inflation is consistent with Planck2018 TT, TE, EE+low E+lensing data at 95$\%$ CL, in some ranges of the model's parameters space as $40\leq n \leq 55$ where the model is instabilities-free in these ranges of parameters too. For the constant sound speed, by adopting some sample values of $c_{s}$, we study both DBI and Mimetic DBI model numerically and find $n\sim 10^{2}$ for DBI model and $n\sim 10$ for Mimetic DBI model. We also compare the results with Planck2018 TT, TE, EE+low E+lensing+BK14+BAO data and see that the DBI and Mimetic DBI model with varying sound speed are ruled out with these joint data. However, these models with constant sound speed are consistent with Planck2018 TT, TE, EE+low E+lensing+BK14+BAO data with $n\sim 10^{2}$ for DBI model and $n\sim 10$ for Mimetic DBI model. In this case, we find some tighter constraints on the corresponding sound speed.

[61]  arXiv:1912.06081 [pdf, ps, other]

Title: The UV/optical peak and X-ray brightening in TDE candidate AT2019azh: A case of stream-stream collision and delayed accretion

Authors: Xiao-Long Liu (1), Li-Ming Dou (2), Rong-Feng Shen (1), Jin-Hong Chen (1) ((1) Sun Yat-Sen U., (2) Guangzhou U.)

Comments: 11 pages, 9 figures, 2 tables. Submitted to ApJ

Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Astrophysics of Galaxies (astro-ph.GA)

We present and analyze the optical/UV and X-ray observations of a nearby tidal disruption event (TDE) candidate AT2019azh, spanning from 30 d before to ~ 250 d after its early optical peak. The X-rays show a late brightening by a factor of ~ 30-100 around 250 days after discovery, while the UV/opticals continuously decayed. The early X-rays show two flaring episodes of variation, temporally uncorrelated with the early UV/opticals. We found a clear sign of X-ray hardness evolution, i.e., the source is harder at early times, and becomes softer as it brightens later. The drastically different temporal behaviors in X-rays and UV/opticals suggest that the two bands are physically distinct emission components, and probably arise from different locations. These properties argue against the reprocessing of X-rays by any outflow as the origin of the UV/optical peak. The full data are best explained by a two-process scenario, in which the UV/optical peak is produced by the debris stream-stream collisions during the circularization phase; some low angular momentum, shocked gas forms an early, low-mass accretion disk which emits the early X-rays. The major body of the disk is formed after the circularization finishes, whose enhanced accretion rate produces the late X-ray brightening. AT2019azh is a strong case of TDE whose emission signatures of stream-stream collision and delayed accretion are both identified.

[62]  arXiv:1912.06094 [pdf, ps, other]

Title: Infrared photometry of the dwarf nova V2051 Ophiuchi: II -- The quiescent accretion disc and its spiral arms

Authors: Raymundo Baptista, Eduardo Wojcikiewicz

Comments: 11 pages, 6 figures, accepted for publication at MNRAS

Subjects: Solar and Stellar Astrophysics (astro-ph.SR); High Energy Astrophysical Phenomena (astro-ph.HE)

We report the analysis of time-series of infrared $JHK_s$ photometry of the dwarf nova V2051 Oph in quiescence with eclipse mapping techniques to investigate structures and the spectrum of its accretion disc. The light curves after removal of the ellipsoidal variations caused by the mass-donor star show a double-wave modulation signalling the presence of two asymmetric light sources in the accretion disc. Eclipse maps reveal two spiral arms on top of the disc emission, one at $R_1= 0.28\pm 0.02 \,R_\mathrm{L1}$ and the other at $R_2= 0.42\pm 0.02 \,R_\mathrm{L1}$ (where $R_\mathrm{L1}$ is the distance from disc centre to the inner Lagrangian point), which are seen face-on at binary phases consistent with the maxima of the double-wave modulation. The wide open angle inferred for the spiral arms ($\theta_s= 21^o \pm 4^o$) suggests the quiescent accretion disc of V2051 Oph has high viscosity. The accretion disc is hot and optically thin in its inner regions ($T_\mathrm{gas}\sim 10-12 \times 10^3\,K$ and surface densities $\sim 10^{-3}-10^{-2}\,g\,cm^{-2}$), and becomes cool and opaque in its outer regions.

[63]  arXiv:1912.06098 [pdf]

Title: Temperature Profiles of Hot Gas In Early Type Galaxies

Authors: Dong-Woo Kim, Liam Traynor, Alessandro Paggi, Ewan O'Sullivan, Craig Anderson, Douglas Burke, Raffaele D'Abrusco, Giuseppina Fabbiano, Antonella Fruscione, Jennifer Lauer, Michael McCollough, Douglas Morgan, Amy Mossman, Saeqa Vrtilek, Ginevra Trinchieri

Comments: 36 pages, 11 figures, accepted or publication in MNRAS

Subjects: Astrophysics of Galaxies (astro-ph.GA); High Energy Astrophysical Phenomena (astro-ph.HE)

Using the data products of the Chandra Galaxy Atlas (Kim et al. 2019a), we have investigated the radial profiles of the hot gas temperature in 60 early type galaxies. Considering the characteristic temperature and radius of the peak, dip, and break (when scaled by the gas temperature and virial radius of each galaxy), we propose a universal temperature profile of the hot halo in ETGs. In this scheme, the hot gas temperature peaks at RMAX = 35 +/- 25 kpc (or ~0.04 RVIR) and declines both inward and outward. The temperature dips (or breaks) at RMIN (or RBREAK) = 3 - 5 kpc (or ~0.006 RVIR). The mean slope between RMIN (RBREAK) and RMAX is 0.3 +/- 0.1. Allowing for selection effects and observational limits, we find that the universal temperature profile can describe the temperature profiles of 72% (possibly up to 82%) of our ETG sample. The remaining ETGs (18%) with irregular or monotonically declining profiles do not fit the universal profile and require another explanation. The temperature gradient inside RMIN (RBREAK) varies widely, indicating different degrees of additional heating at small radii. Investigating the nature of the hot core (HC with a negative gradient inside RMIN), we find that HC is most clearly visible in small galaxies. Searching for potential clues associated with stellar, AGN feedback, and gravitational heating, we find that HC may be related to recent star formation. But we see no clear evidence that AGN feedback and gravitational heating play any significant role for HC.

[64]  arXiv:1912.06104 [pdf, other]

Title: Probing cosmological fields with gravitational wave oscillations

Authors: Jose Beltrán Jiménez, Jose María Ezquiaga, Lavinia Heisenberg

Comments: 36 pages, 9 figures

Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)

Gravitational wave (GW) oscillations occur whenever there are additional tensor modes interacting with the perturbations of the metric coupled to matter. These extra modes can arise from new spin-2 fields (as in e.g. bigravity theories) or from non-trivial realisations of the cosmological principle induced by background vector fields with internal symmetries (e.g. Yang-Mills, gaugids or multi-Proca). We develop a general cosmological framework to study such novel features due to oscillations. The evolution of the two tensor modes is described by a linear system of coupled second order differential equations exhibiting friction, velocity, chirality and mass mixing. We follow appropriate schemes to obtain approximate solutions for the evolution of both modes and show the corresponding phenomenology for different mixings. Observational signatures include modulations of the wave-form, oscillations of the GW luminosity distance, anomalous GW speed and chirality. We discuss the prospects of observing these effects with present and future GW observatories such as LIGO/VIRGO and LISA.

[65]  arXiv:1912.06107 [pdf, ps, other]

Title: Sharp-Lined and Slowly Rotating Ap Stars

Authors: Gautier Mathys

Comments: 11 pages, 1 figure. Conference proceedings: "Stellar Magnetic Fields - A workshop in honour of the career and contributions of John Landstreet", London, Canada, 2019 (to be published in the Proceedings of the Polish Astronomical Society)

Subjects: Solar and Stellar Astrophysics (astro-ph.SR)

One of the most intriguing properties of the Ap (and Bp) stars is their slow rotation, compared to the superficially normal main-sequence stars in the same temperature range. In recent years, it has emerged that several percent of the Ap stars have rotation periods exceeding one year, and that the longest rotation periods reach several centuries. Perhaps even more puzzling is the spread of the rotation periods of the Ap stars, as some of them are as short as 0.5 d. Thus, the rotation periods of these stars span 5 to 6 orders of magnitude, with no evidence for evolution besides conservation of the angular momentum during their main-sequence lifetime. Explaining how period differentiation over such a wide range is achieved in stars that are essentially at the same evolutionary stage represents a major challenge.
Consideration of the extremely slowly rotating Ap stars is of particular importance for the understanding of the origin and the evolution of the rotational properties of Ap stars as a class. We review recent progress in the knowledge of the periods and magnetic fields of the sharpest-lined and most slowly rotating Ap stars, and discuss the prospects and concerns for future progress in their study.

[66]  arXiv:1912.06109 [pdf, other]

Title: A Twilight Search for Atiras, Vatiras and Co-orbital Asteroids: Preliminary Results

Authors: Quanzhi Ye, Frank J. Masci, Wing-Huen Ip, Thomas A. Prince, George Helou, Davide Farnocchia, Eric C. Bellm, Richard Dekany, Matthew J. Graham, Shrinivas R. Kulkarni, Thomas Kupfer, Ashish Mahabal, Chow-Choong Ngeow, Daniel J. Reiley, Maayane T. Soumagnac

Comments: AJ accepted

Subjects: Earth and Planetary Astrophysics (astro-ph.EP)

Near-Earth Objects (NEOs) that orbit the Sun on or within Earth's orbit are tricky to detect for Earth-based observers due to their proximity to the Sun in the sky. These small bodies hold clues to the dynamical history of the inner solar system as well as the physical evolution of planetesimals in extreme environments. Populations in this region include the Atira and Vatira asteroids, as well as Venus and Earth co-orbital asteroids. Here we present a twilight search for these small bodies, conducted using the 1.2-m Oschin Schmidt and the Zwicky Transient Facility (ZTF) camera at Palomar Observatory. The ZTF twilight survey operates at solar elongations down to $35^\circ$ with limiting magnitude of $r=19.5$. During a total of 40 evening sessions and 62 morning sessions conducted between 2018 November 15 and 2019 June 23, we detected 6 Atiras, including 2 new discoveries 2019 AQ$_3$ and 2019 LF$_6$, but no Vatiras or Earth/Venus co-orbital asteroids. NEO population models show that these new discoveries are likely only the tip of the iceberg, with the bulk of the population yet to be found. The population models also suggest that we have only detected 5--$7\%$ of the $H<20$ Atira population over the 7-month survey. Co-orbital asteroids are smaller in diameters and require deeper surveys. A systematic and efficient survey of the near-Sun region will require deeper searches and/or facilities that can operate at small solar elongations.

[67]  arXiv:1912.06120 [pdf, other]

Title: Solar Flare Intensity Prediction with Machine Learning Models

Authors: Zhenbang Jiao, Hu Su, Xiantong Wang, Ward Manchester, Tamas Gombosi, Alfred Hero, Yang Chen

Comments: 27 pages, 12 figures

Subjects: Solar and Stellar Astrophysics (astro-ph.SR)

We develop a mixed Long Short Term Memory (LSTM) regression model to predict the maximum solar flare intensity within a 24-hour time window 0$\sim$24, 6$\sim$30, 12$\sim$36, 24$\sim$48 hours ahead of time using 6, 12, 24, 48 hours of data (predictors) for each HMI Active Region Patch (HARP). The model makes use of (1) the Space-weather HMI Active Region Patch (SHARP) parameters as predictors and (2) the exact flare intensities instead of class labels recorded in the Geostationary Operational Environmental Satellites (GOES) data set, which serves as the source of the response variables. Compared to solar flare classification, the model offers us more detailed information about the exact maximum flux level, i.e. intensity, for each occurrence of a flare. We also consider classification models built on top of the regression model and obtain encouraging results in solar flare classifications. Our results suggest that the most efficient time period for predicting the solar activity is within 24 hours before the prediction time under LSTM architecture using the SHARP parameters.

Cross-lists for Fri, 13 Dec 19

[68]  arXiv:1912.04276 (cross-list from physics.ins-det) [pdf, other]

Title: Benefits of bolometer Joule stepping and Joule pulsing

Authors: Samantha Lynn Stever, François Couchot, Valentin Sauvage, Noël Coron

Comments: Accepted for publication in the Journal of Low Temperature Physics

Subjects: Instrumentation and Detectors (physics.ins-det); Cosmology and Nongalactic Astrophysics (astro-ph.CO); Instrumentation and Methods for Astrophysics (astro-ph.IM)

We introduce the `Joule stepping' technique, whereupon a constantly-biased bolometer has its bias voltage modified by a small additional step. We demonstrate this technique using a composite NTD semiconductor bolometer and a pulsing device which sends an extra step in voltage. We demonstrate the results of the technique over a range of bias voltages at 100, 200, and 300 mK. We find that Joule stepping allows us to directly measure long thermal tails with low amplitudes in the bolometer response, and could be a useful tool for quickly and easily understanding response functions of bolometric detectors. We also show that the derivative of the Joule step is equivalent to the bolometer response to a $\delta$-pulse (or Joule pulse), which allows for greater understanding of fast transient behaviour.

[69]  arXiv:1912.05558 (cross-list from hep-ph) [pdf, other]

Title: Prospects for Detecting Boosted Dark Matter in DUNE through Hadronic Interactions

Authors: Joshua Berger, Yanou Cui, Mathew Graham, Lina Necib, Gianluca Petrillo, Dane Stocks, Yun-Tse Tsai, Yue Zhao

Comments: 13 pages, 4 figures

Subjects: High Energy Physics - Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Experiment (hep-ex)

Boosted dark matter (BDM) is a well-motivated class of dark matter candidates in which a small subcomponent is relativistic at the present time. In this work, we lay the foundation for BDM searches via its hadronic interactions at DUNE. We investigate BDM-nucleus scattering in detail by developing new dedicated event generation techniques with a parameterized detector simulation. We demonstrate that the excellent event reconstruction capability of DUNE enables a significantly broader discovery reach.

[70]  arXiv:1912.05572 (cross-list from hep-ph) [pdf, other]

Title: Getting a THUMP from a WIMP

Authors: Hooman Davoudiasl, Gopolang Mohlabeng

Comments: 6 pages, 3 figures

Subjects: High Energy Physics - Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO)

Producing an acceptable thermal relic abundance of dark matter with masses $\gg 10^2$ TeV is a challenge. We propose a novel mechanism where GeV-scale states establish a tiny thermal relic abundance for dark matter, which is later promoted to ultra massive status by a very light scalar. We refer to this dark matter as a THermal Ultra Massive Particle (THUMP). Direct detection of THUMPs can be naturally expected due to large scattering cross sections mediated by low mass states that couple THUMPs to the Standard Model. Our model generically leads to signals for the associated GeV-scale states at accelerator experiments.

[71]  arXiv:1912.05581 (cross-list from hep-ph) [pdf, other]

Title: Loop Dominated Signals from Neutrino Portal Dark Matter

Authors: Hiren H. Patel, Stefano Profumo, Bibhushan Shakya

Comments: 7 pages, 2 figures

Subjects: High Energy Physics - Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO)

We study scenarios where loop processes give the dominant contributions to dark matter decay or annihilation despite the presence of tree level channels. We illustrate this possibility in a specific model where dark matter is part of a hidden sector that communicates with the Standard Model sector via a heavy neutrino portal. We explain the underpinning rationale for how loop processes mediated by the portal neutrinos can parametrically dominate over tree level decay channels, and demonstrate that this qualitatively changes the indirect detection signals in positrons, neutrinos, and gamma rays.

[72]  arXiv:1912.05584 (cross-list from gr-qc) [pdf, other]

Title: On Black Hole Echoes

Authors: Guido D'Amico, Nemanja Kaloper

Comments: 10 pages, 3 figures

Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Theory (hep-th)

We consider gravitational wave echoes from black hole merger ringdowns which may arise from local Lorentz symmetry violations that modify graviton dispersion relations. If the corrections are sufficiently soft so they do not remove the horizon, the reflection of the infalling waves which trigger the echoes is very weak. As an example, we look at the dispersion relation corrected by roton-like operators depending only on spatial momenta, in Gullstrand-Painlev\'e coordinates. The near-horizon regions of a black hole do become reflective, but only very weakly. The resulting "bounces" of infalling waves can yield repetitive gravity wave emissions but their power is very small. This implies that to see any echoes from black holes we really need an egregious departure from either standard GR or effective field theory, or both.

[73]  arXiv:1912.05587 (cross-list from physics.hist-ph) [pdf, other]

Title: Shadow of the Moon and general relativity: Einstein, Dyson, Eddington and the 1919 light deflection

Authors: José P. S. Lemos

Comments: 63 pages, 39 figures

Journal-ref: Revista Brasileira de Ensino de Fisica 41 suppl 1, e20190260 (2019)

Subjects: History and Philosophy of Physics (physics.hist-ph); Solar and Stellar Astrophysics (astro-ph.SR); General Relativity and Quantum Cosmology (gr-qc)

The eclipse of the Sun of 1919 was fundamental in the development of physics and earns a high place in the history of science. Several players took part in this adventure. The most important are Einstein, Dyson, Eddington, the Sun, the Moon, Sobral, and Principe. Einstein's theory of gravitation, general relativity, had the prediction that the gravitational field of the Sun deflects an incoming light ray from a background star on its way to Earth. The calculation gave that the shift in the star's position was 1.75 arcseconds for light rays passing at the Sun's rim. So to test it definitely it was necessary to be in the right places on May 29, 1919, the day of the eclipse. That indeed happened, with a Royal Greenwich Observatory team composed of Crommelin and Davidson that went to Sobral, and that was led at a distance by the Astronomer Royal Frank Dyson, and with Eddington of Cambridge University that went to Principe with his assistant Cottingham. The adventure is fascinating, from the preparations, to the day of the eclipse, the data analysis, the results, and the history that has been made. It confirmed general relativity, and marked an epoch that helped in delineating science in the post eclipse era up to now and into the future. This year of 2019 we are celebrating this enormous breakthrough

[74]  arXiv:1912.06073 (cross-list from stat.ML) [pdf, other]

Title: Normalizing Constant Estimation with Gaussianized Bridge Sampling

Authors: He Jia, Uroš Seljak

Comments: Accepted by AABI 2019 Proceedings

Subjects: Machine Learning (stat.ML); Cosmology and Nongalactic Astrophysics (astro-ph.CO); Machine Learning (cs.LG); Computation (stat.CO); Methodology (stat.ME)

Normalizing constant (also called partition function, Bayesian evidence, or marginal likelihood) is one of the central goals of Bayesian inference, yet most of the existing methods are both expensive and inaccurate. Here we develop a new approach, starting from posterior samples obtained with a standard Markov Chain Monte Carlo (MCMC). We apply a novel Normalizing Flow (NF) approach to obtain an analytic density estimator from these samples, followed by Optimal Bridge Sampling (OBS) to obtain the normalizing constant. We compare our method which we call Gaussianized Bridge Sampling (GBS) to existing methods such as Nested Sampling (NS) and Annealed Importance Sampling (AIS) on several examples, showing our method is both significantly faster and substantially more accurate than these methods, and comes with a reliable error estimation.

[75]  arXiv:1912.06117 (cross-list from gr-qc) [pdf, other]

Title: Horndeski and the Sirens

Authors: Charles Dalang, Pierre Fleury, Lucas Lombriser

Comments: 14 pages, 1 figure

Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO)

Standard sirens have been proposed as probes of alternative theories of gravity, such as Horndeski models. Hitherto, all studies have been conducted on a homogeneous-isotropic cosmological background, which is unable to consistently account for realistic distributions of matter, and for inhomogeneities in the Horndeski scalar field. Yet, the latter are essential for screening mechanisms. In this article, we comprehensively analyze the propagation of Horndeski gravitational waves in an arbitrary background spacetime and scalar field. We restrict to the class of theories in which gravitational waves propagate at light speed, and work in the geometric-optics regime. We find that kinetic braiding only produces a nonphysical longitudinal mode, whereas conformal coupling affects the amplitude of the standard transverse modes but not their polarization. We confirm that any observable deviation from general relativity depends on the local value of the effective Planck mass at emission and reception of the wave. This result is interpreted as the conservation of the number of gravitons.

Replacements for Fri, 13 Dec 19

[76]  arXiv:1902.03300 (replaced) [pdf, other]

Title: The mass distribution of Galactic double neutron stars

Authors: Nicholas Farrow, Xing-Jiang Zhu, Eric Thrane

Comments: Minor update of PSR J1913+1102 masses, 13 pages, 7 figures, 5 tables

Journal-ref: 2019, ApJ, 876, 18

Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Instrumentation and Methods for Astrophysics (astro-ph.IM); Solar and Stellar Astrophysics (astro-ph.SR); General Relativity and Quantum Cosmology (gr-qc)

[77]  arXiv:1903.08607 (replaced) [pdf, ps, other]

Title: Neutrino Echoes from Multimessenger Transient Sources

Authors: Kohta Murase (PSU), Ian M. Shoemaker (VT)

Comments: 7 pages, 3 figures, 1 table, version published in PRL. Results and conclusions unchanged

Subjects: High Energy Physics - Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Astrophysical Phenomena (astro-ph.HE)

[78]  arXiv:1903.11809 (replaced) [pdf, other]

Title: Gravitational lensing of gravitational waves: wave nature and prospects for detection

Authors: Ashish Kumar Meena, J S Bagla

Comments: 8 pages, 4 figures. Accepted for publication in the MNRAS

Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)

[79]  arXiv:1903.12173 (replaced) [pdf, other]

Title: Painting with baryons: augmenting N-body simulations with gas using deep generative models

Authors: Tilman Tröster, Cameron Ferguson, Joachim Harnois-Déraps, Ian G. McCarthy

Comments: Comments welcome. Code and trained models can be found at this https URL Accepted in MNRAS Letters

Journal-ref: Monthly Notices of the Royal Astronomical Society: Letters, Volume 487, Issue 1, (2019), p.L24-L29

Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Instrumentation and Methods for Astrophysics (astro-ph.IM); Machine Learning (stat.ML)

[80]  arXiv:1904.09999 (replaced) [pdf, other]

Title: Impact of Ly$α$ heating on the global 21-cm signal from the Cosmic Dawn

Authors: Raghunath Ghara, Garrelt Mellema

Comments: 11 Pages, 6 Figures, 2 Tables, Accepted for publication in MNRAS

Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)

[81]  arXiv:1904.10001 (replaced) [pdf, ps, other]

Title: Comments on "Numerical Stability of Detonations in White Dwarf Simulations"

Authors: Doron Kushnir, Boaz Katz (WIS)

Comments: 7 pages, 6 figures. Modified following referee report

Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

[82]  arXiv:1905.12505 (replaced) [pdf, ps, other]

Title: Anisotropies of different mass compositions of cosmic rays

Authors: Bing-Qiang Qiao, Wei Liu, Yi-Qing Guo, Qiang Yuan

Comments: 9 pages, 5 figures

Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

[83]  arXiv:1906.07301 (replaced) [pdf, ps, other]

Title: Standard-Model Extension Constraints on Lorentz and CPT Violation From Optical Polarimetry of Active Galactic Nuclei

Authors: Andrew S. Friedman, David Leon, Roman Gerasimov, Kevin D. Crowley, Isaac Broudy, Yash Melkani, Walker Stevens, Delwin Johnson, Grant Teply, David Tytler, Brian G. Keating, Gary M. Cole

Comments: Presented at the Eighth Meeting on CPT and Lorentz Symmetry, Bloomington, Indiana, May 12-16, 2019; typo in one author name changed from v1

Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Experiment (hep-ex); High Energy Physics - Theory (hep-th)

[84]  arXiv:1908.00557 (replaced) [pdf, other]

Title: Macroscopic Dark Matter Constraints from Bolide Camera Networks

Authors: Jagjit Singh Sidhu, Glenn Starkman

Comments: 7 pages, 1 figure

Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Instrumentation and Methods for Astrophysics (astro-ph.IM); High Energy Physics - Phenomenology (hep-ph)

[85]  arXiv:1908.08585 (replaced) [pdf, other]

Title: An 11 Earth-Mass, Long-Period Sub-Neptune Orbiting a Sun-like Star

Authors: Andrew W. Mayo, Vinesh M. Rajpaul, Lars A. Buchhave, Courtney D. Dressing, Annelies Mortier, Li Zeng, Charles D. Fortenbach, Suzanne Aigrain, Aldo S. Bonomo, Andrew Collier Cameron, David Charbonneau, Adrien Coffinet, Rosario Cosentino, Mario Damasso, Xavier Dumusque, A. F. Martinez Fiorenzano, Raphaëlle D. Haywood, David W. Latham, Mercedes López-Morales, Luca Malavolta, Giusi Micela, Emilio Molinari, Logan Pearce, Francesco Pepe, David Phillips, Giampaolo Piotto, Ennio Poretti, Ken Rice, Alessandro Sozzetti, Stephane Udry

Comments: Published in AJ, 17 pages, 8 figures, 3 tables

Journal-ref: 2019 AJ 158 4

Subjects: Earth and Planetary Astrophysics (astro-ph.EP)

[86]  arXiv:1908.11785 (replaced) [pdf, other]

Title: Exploring the Foundations of the Universe with Space Tests of the Equivalence Principle

Authors: Baptiste Battelier, Joël Bergé, Andrea Bertoldi, Luc Blanchet, Kai Bongs, Philippe Bouyer, Claus Braxmaier, Davide Calonico, Pierre Fayet, Naceur Gaaloul, Christine Guerlin, Aurélien Hees, Philippe Jetzer, Claus Lämmerzahl, Steve Lecomte, Christophe Le Poncin-Lafitte, Sina Loriani, Gilles Métris, Miguel Nofrarias, Ernst Rasel, Serge Reynaud, Manuel Rodrigues, Markus Rothacher, Albert Roura, Christophe Salomon, Stephan Schiller, Wolfgang P. Schleich, Christian Schubert, Carlos Sopuerta, Fiodor Sorrentino, Tim J. Sumner, Guglielmo M. Tino, Philip Tuckey, Wolf von Klitzing, Lisa Wörner, Peter Wolf, Martin Zelan

Comments: White paper submitted to the ESA Voyage 2050 long term plan. Partly derived from Altschul et al., Advances in Space Research, 2015, 55, 501 - 524, arXiv:1404.4307

Subjects: Space Physics (physics.space-ph); Instrumentation and Methods for Astrophysics (astro-ph.IM)

[87]  arXiv:1909.03815 (replaced) [pdf, ps, other]

Title: Waveform of gravitational waves in the ghost-free parity-violating gravities

Authors: Jin Qiao, Tao Zhu, Wen Zhao, Anzhong Wang

Comments: 8 pages, PRD accepted

Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th)

[88]  arXiv:1909.04642 (replaced) [pdf, other]

Title: Water Vapor and Clouds on the Habitable-Zone Sub-Neptune Exoplanet K2-18b

Authors: Björn Benneke, Ian Wong, Caroline Piaulet, Heather A. Knutson, Joshua Lothringer, Caroline V. Morley, Ian J.M. Crossfield, Peter Gao, Thomas P. Greene, Courtney Dressing, Diana Dragomir, Andrew W. Howard, Peter R. McCullough, Eliza M.-R. Kempton, Jonathan J. Fortney, Jonathan Fraine

Comments: Published in ApJL, includes important updates to stellar and planet parameters

Journal-ref: ApJL, 887, L14 (2019)

Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM)

[89]  arXiv:1909.06190 (replaced) [pdf, other]

Title: Measuring galaxy-galaxy-galaxy-lensing with higher precision and accuracy

Authors: Laila Linke, Patrick Simon, Peter Schneider, Stefan Hilbert

Comments: 15 pages, 10 figures, replaced by revised version accepted for A&A after addressing referees comments

Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)

[90]  arXiv:1909.10887 (replaced) [pdf, other]

Title: Waveform of gravitational waves in the general parity-violating gravities

Authors: Wen Zhao, Tao Zhu, Jin Qiao, Anzhong Wang

Comments: 13 pages, no fig, no table. PRD accepted. arXiv admin note: text overlap with arXiv:1909.03815

Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th)

[91]  arXiv:1910.01163 (replaced) [pdf, other]

Title: Evolution of giant molecular clouds across cosmic time

Authors: David Guszejnov, Michael Y. Grudić, Stella S. R. Offner, Michael Boylan-Kolchin, Claude-André Faucher-Gigère, Andrew Wetzel, Samantha M. Benincasa, Sarah Loebman

Comments: 15 pages, 11 figures accepted by MNRAS

Subjects: Astrophysics of Galaxies (astro-ph.GA)

[92]  arXiv:1911.09434 (replaced) [pdf, other]

Title: Probing the Properties of the Pulsar Wind in the Gamma-Ray Binary HESS J0632+057 with NuSTAR and VERITAS Observations

Authors: A. Archer, W. Benbow, R. Bird, A. Brill, R. Brose, M. Buchovecky, J. L. Christiansen, A. J. Chromey, W. Cui, A. Falcone, Q. Feng, J. P. Finley, L. Fortson, A. Furniss, A. Gent, G. H. Gillanders, C. Giuri, O. Gueta, D. Hanna, T. Hassan, O. Hervet, J. Holder, G. Hughes, T. B. Humensky, P. Kaaret, N. Kelley-Hoskins, M. Kertzman, D. Kieda, M. Krause, M. J. Lang, G. Maier, P. Moriarty, R. Mukherjee, D. Nieto, M. Nievas-Rosillo, S. O'Brien, R. A. Ong, A. N. Otte, N. Park, A. Petrashyk, K. Pfrang, M. Pohl, R. R. Prado, E. Pueschel, J. Quinn, K. Ragan, P. T. Reynolds, D. Ribeiro, G. T. Richards, E. Roache, I. Sadeh, M. Santander, S. Schlenstedt, G. H. Sembroski, I. Sushch, A. Weinstein, P. Wilcox, A. Wilhelm, D. A. Williams, T. J Williamson, C. J. Hailey, S. Mandel, K. Mori

Comments: Accepted for publication in The Astrophysical Journal

Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

[93]  arXiv:1911.11755 (replaced) [pdf, other]

Title: AION: An Atom Interferometer Observatory and Network

Authors: L. Badurina, E. Bentine, D. Blas, K. Bongs, D. Bortoletto, T. Bowcock, K. Bridges, W. Bowden, O. Buchmueller, C. Burrage, J. Coleman, G. Elertas, J. Ellis, C. Foot, V. Gibson, M. G. Haehnelt, T. Harte, S. Hedges, R. Hobson, M. Holynski, T. Jones, M. Langlois, S. Lellouch, M. Lewicki, R. Maiolino, P. Majewski, S. Malik, J. March-Russell, C. McCabe, D. Newbold, B. Sauer, U. Schneider, I. Shipsey, Y. Singh, M. A. Uchida, T. Valenzuela, M. van der Grinten, V. Vaskonen, J. Vossebeld, D. Weatherill, I. Wilmut

Comments: v2: Update/add references and minor corrections

Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Experiment (hep-ex); High Energy Physics - Phenomenology (hep-ph); Atomic Physics (physics.atom-ph)

[94]  arXiv:1912.00607 (replaced) [pdf, other]

Title: A refined trans-Planckian censorship conjecture

Authors: Rong-Gen Cai, Shao-Jiang Wang

Comments: v1, 6 pages; v2, 8 pages, references added, discussion added for eternal inflation

Subjects: High Energy Physics - Theory (hep-th); Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc)

[95]  arXiv:1912.00997 (replaced) [pdf, other]

Title: Constraining strongly supercooled phase transitions by overproduction of black holes

Authors: Marek Lewicki, Ville Vaskonen

Comments: 6 pages, 5 figures. minor improvements and expanded discussion

Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph)

[96]  arXiv:1912.01743 (replaced) [pdf, other]

Title: Apparent superluminal core expansion and limb brightening in the candidate neutrino blazar TXS 0506+056

Authors: E. Ros (MPIfR Bonn), M. Kadler (U. Würzburg), M. Perucho (U. València), B. Boccardi (MPIfR Bonn), H.-M. Cao (IRA-INAF Bologna), M. Giroletti (IRA-INAF Bologna), F. Krauß (Penn State Univ.), R. Ojha (NASA/GSFC, U. Maryland, Catholic U. America)

Comments: Accepted for publication in Astronomy & Astronomy Letters; 5 pages, 3 figures, 2 tables

Subjects: Astrophysics of Galaxies (astro-ph.GA); High Energy Astrophysical Phenomena (astro-ph.HE)

[97]  arXiv:1912.03669 (replaced) [pdf, other]

Title: SCUBA-2 Ultra Deep Imaging Eao Survey (Studies) III: Multi-wavelength properties, luminosity functions and preliminary source catalog of 450-$μ$m-selected galaxies

Authors: Chen-Fatt Lim, Wei-Hao Wang, Ian Smail, Douglas Scott, Chian-Chou Chen, Yu-Yen Chang, James M. Simpson, Yoshiki Toba, Xinwen Shu, Dave Clements, Josh Greenslade, YiPing Ao, Arif Babul, Jack Birkin, Scott C. Chapman, Tai-An Cheng, Brian S. Cho, Helmut Dannerbauer, Ugnė Dudzevičiūtė, James Dunlop, Yu Gao, Tomotsugu Goto, Luis C. Ho, Li-Ting Hsu, Ho Seong Hwang, Woong-Seob Jeong, Maciej Koprowski, Chien-Hsiu Lee, Ming-Yi Lin, Wei-Ching Lin, Michał J. Michałowski, Harriet Parsons, Marcin Sawicki, Raphael Shirley, Hyunjin Shim, Sheona Urquhart, Jianfa Wang, Tao Wang

Comments: ApJ accepted

Subjects: Astrophysics of Galaxies (astro-ph.GA)

[98]  arXiv:1912.03701 (replaced) [pdf, other]

Title: Hamilton-Jacobi hydrodynamics of pulsating relativistic stars

Authors: John Ryan Westernacher-Schneider, Charalampos Markakis, Bing Jyun Tsao

Comments: 24 pgs, 3 figs. Typo fixed

Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE)

[99]  arXiv:1912.04970 (replaced) [pdf, other]

Title: AUTO-MULTITHRESH: A General Purpose Automasking Algorithm

Authors: Amanda A. Kepley, Takahiro Tsutsumi, Crystal L. Brogan, Remy Indebetouw, Ilsang Yoon, Brian Mason, Jennifer Donovan Meyer

Comments: accepted to PASP

Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)

[100]  arXiv:1912.05429 (replaced) [pdf, other]

Title: Cosmological-scale parity violation of galaxy spin patterns

Authors: Lior Shamir

Comments: To be submitted. Comments welcome

Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)

[101]  arXiv:1912.05461 (replaced) [pdf, other]

Title: Long term operation with the DarkSide-50 detector

Authors: N. Canci (on behalf of DarkSide-50 Collaboration)

Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Experiment (hep-ex); Instrumentation and Detectors (physics.ins-det)

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