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Astrophysics

New submissions

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New submissions for Tue, 11 Feb 20

[1]  arXiv:2002.02965 [pdf, other]
Title: Structural diversity of disc galaxies originating in the cold gas inflow from cosmic webs
Authors: Masafumi Noguchi
Comments: 5 pages, 5 figures. Accepted for publication in MNRAS Letters. Also includes Supplementary Material (2 pages). arXiv admin note: text overlap with arXiv:1905.08993
Subjects: Astrophysics of Galaxies (astro-ph.GA)

Disc galaxies show a large morphological diversity with varying contribution of three major structural components; thin discs, thick discs, and central bulges. Dominance of bulges increases with the galaxy mass (Hubble sequence) whereas thick discs are more prominent in lower mass galaxies. Because galaxies grow with the accretion of matter, this observed variety should reflect diversity in accretion history. On the basis of the prediction by the cold-flow theory for galactic gas accretion and inspired by the results of previous studies, we put a hypothesis that associates different accretion modes with different components. Namely, thin discs form as the shock-heated hot gas in high-mass halos gradually accretes to the central part, thick discs grow by the direct accretion of cold gas from cosmic webs when the halo mass is low, and finally bulges form by the inflow of cold gas through the shock-heated gas in high-redshift massive halos. We show that this simple hypothesis reproduces the mean observed variation of galaxy morphology with the galaxy mass. This scenario also predicts that thick discs are older and poorer in metals than thin discs, in agreement with the currently available observational data.

[2]  arXiv:2002.02968 [pdf, other]
Title: Interpreting the Spitzer/IRAC Colours of 7<z<9 Galaxies: Distinguishing Between Line Emission and Starlight Using ALMA
Comments: 9 pages, 6 figures. Submitted to MNRAS, comments welcome
Subjects: Astrophysics of Galaxies (astro-ph.GA)

Prior to the launch of JWST, Spitzer/IRAC photometry offers the only means of studying the rest-frame optical properties of z>7 galaxies. Many such high redshift galaxies display a red [3.6] - [4.5] micron colour, often referred to as the "IRAC excess", which has conventionally been interpreted as arising from intense [OIII]+Hbeta emission within the [4.5] micron bandpass. An appealing aspect of this interpretation is similarly intense line emission seen in star-forming galaxies at lower redshift as well as the redshift-dependent behaviour of the IRAC colours beyond z~7 modelled as the various nebular lines move through the two bandpasses. In this paper we demonstrate that, given the photometric uncertainties, established stellar populations with Balmer (4000 A, rest-frame) breaks, such as those inferred at z>9 where line emission does not contaminate the IRAC bands, can equally well explain the redshift-dependent behaviour of the IRAC colours in 7<z<9 galaxies. We discuss possible ways of distinguishing between the two hypotheses using ALMA measures of [OIII] 88 micron and dust continuum fluxes. Prior to further studies with JWST, we show that the distinction is important in determining the assembly history of galaxies in the first 500 Myr.

[3]  arXiv:2002.02974 [pdf, other]
Title: Deceptively cold dust in the massive starburst galaxy GN20 at $z\sim4$
Authors: Isabella Cortzen (1 and 2), Georgios E. Magdis (1, 2, and 3), Francesco Valentino (1 and 2), Emanuele Daddi (4), Daizhong Liu (5), Dimitra Rigopoulou (6), Mark Sargent (7), Dominik Riechers (8), Diane Cormier (4), Jacqueline A. Hodge (9), Fabian Walter (5), David Elbaz (4), Matthieu Béthermin (11), Thomas R. Greve (1 and 12), Vasily Kokorev (1 and 2), Sune Toft (1 and 2) ((1) Cosmic Dawn Center (2) Niels Bohr Institute - University of Copenhagen (3) DTU Space - Technical University of Denmark (4) CEA Saclay (5) MPIA Heidelberg (6) Department of Physics, Univeristy of Oxford (7) Astronomy Centre, Department of Physics and Astronomy, University of Sussex (8) Department of Astronomy, Cornell University (9) Leiden Observatory, Leiden University (10) Max-Planck-Institut fur Radioastronomie (11) Aix Marseille Univ., Centre National de la Recherche Scientifique (12) Department of Physics and Astronomy, University College London)
Comments: Comments: 6 pages, 4 figures, accepted for publication in Astronomy and Astrophysics Letters on February 4th 2020
Subjects: Astrophysics of Galaxies (astro-ph.GA)

We present new observations, carried out with IRAM NOEMA, of the atomic neutral carbon transitions [CI](1-0) at 492 GHz and [CI](2-1) at 809 GHz of GN20, a well-studied star-bursting galaxy at $z=4.05$. The high luminosity line ratio [CI](2-1)/[CI](1-0) implies an excitation temperature of $48^{+14}_{-9}$ K, which is significantly higher than the apparent dust temperature of $T_{\rm d}=33\pm2$ K ($\beta=1.9$) derived under the common assumption of an optically thin far-infrared dust emission, but fully consistent with $T_{\rm d}=52\pm5$ K of a general opacity model where the optical depth ($\tau$) reaches unity at a wavelength of $\lambda_0=170\pm23$ $\mu$m. Moreover, the general opacity solution returns a factor of $\sim 2\times$ lower dust mass and, hence, a lower molecular gas mass for a fixed gas-to-dust ratio, than with the optically thin dust model. The derived properties of GN20 thus provide an appealing solution to the puzzling discovery of starbursts appearing colder than main-sequence galaxies above $z>2.5$, in addition to a lower dust-to-stellar mass ratio that approaches the physical value predicted for starburst galaxies.

[4]  arXiv:2002.02975 [pdf, other]
Title: Gravitational-wave captures by intermediate-mass black holes in galactic nuclei
Comments: 10 pages, 5 figures
Subjects: Astrophysics of Galaxies (astro-ph.GA); High Energy Astrophysical Phenomena (astro-ph.HE)

Intermediate-mass black holes (IMBHs) have not been detected beyond any reasonable doubt, despite their important role as massive seeds for quasars and sources of tidal disruption events, ultra-luminous X-ray sources, dwarf galaxy feedback, and hypervelocity stars. Gravitational wave (GW) observations can help to find and confirm the existence of IMBHs. Current and upcoming detectors, such as LIGO, Virgo, KAGRA, LISA, ET, and DECIGO promise to identify the full range from stellar-mass to supermassive black holes (SMBHs). In this paper, we address the question of whether IMBHs can produce GWs in galactic nuclei. We consider the possibility that stellar black holes (SBHs) form bound systems and later coalesce with an IMBH through gravitational captures in the dense nucleus. We show that this mechanism is efficient for IMBH masses in the range $\sim 3\times 10^3\,$M$_{\odot}$--$2\times 10^4\,$M$_{\odot}$. We find that the typical distributions of peak frequencies and merger timescales depend mainly on the IMBH mass. In particular, the typical peak frequency is about $0.2\,$Hz, $0.1\,$Hz, $0.09\,$Hz, and $0.05\,$Hz for $M_{\rm IMBH}=5\times 10^3\,$M$_{\odot}$, $8\times 10^3\,$M$_{\odot}$, $1\times 10^4\,$M$_{\odot}$, and $2\times 10^4\,$M$_{\odot}$, respectively. Our results show that, at design sensitivity, both DECIGO and ET should be able to detect these IMBH--SBH mergers. Furthermore, most of the mergers will appear eccentric ($e \gtrsim 0.1$), providing an indication of their dynamical origin.

[5]  arXiv:2002.02976 [pdf, ps, other]
Title: What Drives the Redshift Evolution of Strong Emission Line Ratios?
Comments: 7 pages, 5 figures. accepted for publication in MNRAS
Subjects: Astrophysics of Galaxies (astro-ph.GA)

We study the physical mechanisms that cause the offset between low-redshift and high-redshift galaxies on the [OIII]/H$\beta$ versus [NII]/H$\alpha$ ``Baldwin, Phillips & Terlevich'' (BPT) diagram using a sample of local analogues of high-redshift galaxies. These high-redshift analogue galaxies are selected from the Sloan Digital Sky Survey. Located in the same region on the BPT diagram as the ultra-violet selected galaxies at $z\sim2$, these high-redshift analogue galaxies provide an ideal local benchmark to study the offset between the local and high-redshift galaxies on the BPT diagram. We compare the nitrogen-to-oxygen ratio (N/O), the shape of the ionising radiation field, and ionisation parameters between the high-redshift analogues and a sample of local reference galaxies. The higher ionisation parameter in the high-redshift analogues is the dominant physical mechanism driving the BPT offset from low- to high-redshift, particularly at high {\nii/\ha}. Furthermore, the N/O ratio enhancement also plays a minor role to cause the BPT offset. However, the shape of the ionising radiation field is unlikely to cause the BPT offset because the high-redshift analogues have a similar hard ionising radiation field as local reference galaxies. This hard radiation field cannot be produced by the current standard stellar synthesis models. The stellar rotation and binarity may help solve the discrepancy.

[6]  arXiv:2002.02977 [pdf, other]
Title: Atmospheric Erosion by Giant Impacts onto Terrestrial Planets
Comments: 17 pages, 13 figures, submitted to ApJ
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)

We examine the mechanisms by which atmosphere can be eroded by giant impacts onto Earth-like planets with thin atmospheres, using 3D smoothed particle hydrodynamics simulations with sufficient resolution to directly model the fate of low-mass atmospheres for the first time. We present a simple scaling law to estimate the fraction lost for any impact angle and speed in this regime. In the canonical Moon-forming impact, only around 10% of the atmosphere would have been lost from the immediate effects of the collision. There is a gradual transition from removing almost none to almost all of the atmosphere for a grazing impact as it becomes more head-on or increases in speed, including complex, non-monotonic behaviour at low impact angles. In contrast, for head-on impacts, a slightly greater speed can suddenly remove much more atmosphere. Our results broadly agree with the application of 1D models of local atmosphere loss to the ground speeds measured directly from our simulations. However, previous analytical models of shock-wave propagation from an idealised point-mass impact significantly underestimate the ground speeds and hence the total erosion. The strong dependence on impact angle and the interplay of multiple non-linear and asymmetrical loss mechanisms highlight the need for 3D simulations in order to make realistic predictions.

[7]  arXiv:2002.02978 [pdf, ps, other]
Title: The X-Ray Cavity Around Hotspot E in Cygnus A: Tunneled by a Deflected Jet
Comments: Accepted to ApJ, 12 pages, 7 figures, 5 tables
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

The powerful FR II radio galaxy Cygnus A exhibits primary and secondary hotspots in each lobe. A 2 Msec Chandra X-ray image of Cygnus A has revealed an approximately circular hole, with a radius of 3.9 kpc, centered on the primary hotspot in the eastern radio lobe, hotspot E. We infer the distribution of X-ray emission on our line-of-sight from an X-ray surface brightness profile of the radio lobe adjacent to the hole and use it to argue that the hole is excavated from the radio lobe. The surface brightness profile of the hole implies a depth at least 1.7 $\pm$ 0.3 times greater than its projected width, requiring a minimum depth of 13.3 $\pm$ 2.3 kpc. A similar hole observed in the 5 GHz VLA radio map reinforces the argument for a cavity lying within the lobe. We argue that the jet encounters the shock compressed intracluster medium at hotspot E, passing through one or more shocks as it is deflected back into the radio lobe. The orientation of Cygnus A allows the outflow from hotspot E to travel almost directly away from us, creating an elongated cavity, as observed. These results favor models for multiple hotspots in which an FR II jet is deflected at a primary hotspot, then travels onward to deposit the bulk of its power at a secondary hotspot, rather than the dentist drill model.

[8]  arXiv:2002.02980 [pdf, other]
Title: The role of galaxy mass on AGN emission: a view from the VANDELS survey
Comments: 18 pages, 18 figures, to appear on MNRAS
Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Astrophysical Phenomena (astro-ph.HE)

We present a comparative analysis of the properties of AGN emitting at radio and X-ray wavelengths. The study is performed on 907 X-ray AGN and 100 radio AGN selected on the CDFS and UDS fields and makes use of new and ancillary data available to the VANDELS collaboration. Our results indicate that the mass of the host galaxy is a fundamental quantity which determines the level of AGN activity at the various wavelengths. Indeed large stellar masses are found to be connected with AGN radio emission, as virtually all radio-active AGN reside within galaxies of M*>10^{10} Msun. Large stellar masses also seem to favour AGN activity in the X-ray, even though X-ray AGN present a mass distribution which is more spread out and with a non-negligible tail at M*<10^{9} Msun. Stellar mass alone is also observed to play a fundamental role in simultaneous radio and X-ray emission: the percentage of AGN active at both wavelengths increases from around 1% of all X-ray AGN residing within hosts of M*<10^{11} Msun to about 13% in more massive galaxies. In the case of radio-selected AGN, such a percentage moves from about 15% to about 45% (but up to 80% in the deepest fields). Neither cosmic epoch, nor radio luminosity, X-ray luminosity, Eddington ratio or star-formation rate of the hosts are found to be connected to an enhanced probability for joint radio+X-ray emission of AGN origin. Furthermore, only a loose relation is observed between X-ray and radio luminosity in those AGN which are simultaneously active at both frequencies.

[9]  arXiv:2002.02981 [pdf, other]
Title: Black hole mass function and its evolution -- the first prediction for the Einstein Telescope
Comments: 9 pages, 4 figures, 1 table; Accepted by ApJ
Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)

The knowledge about the black hole mass function (BHMF) and its evolution would help to understand the origin of the BHs and how BH binaries formed at different stages of the history of the Universe. We demonstrate the ability of future third generation gravitational wave (GW) detector -- the Einstein Telescope (ET) to infer the slope of the BHMF and its evolution with redshift. We perform the Monte Carlo simulation of the measurements of chirp signals from binary BH systems (BBH) that could be detected by ET, including the BH masses and their luminosity distances ($d_L$). We use the mass of a primary black hole in each binary system to infer the BHMF as a power-law function with slope parameter as $\alpha$. Taking into account the bias that could be introduced by the uncertainty of measurements and by the selection effect, we carried out the numerical tests and find that only one thousand of GW events registered by ET ($\sim1\%$ amount of its yearly detection rate) could accurately infer the $\alpha$ with a precision of $\alpha\sim0.1$. Furthermore, we investigate the validity of our method to recover a scenario where $\alpha$ evolves with redshift as $\alpha(z) = \alpha_0 + \alpha_1\frac{z}{1+z}$. Taking a thousand of GW events and using $d_L$ as the redshift estimator, our tests show that one could infer the value of evolving parameter $\alpha_1$ accurately with the uncertainty level of $\sim0.5$. Our numerical tests verify the reliability of our method. The uncertainty levels of the inferred parameters can be trusted directly for the several sets of the parameter we assumed, yet shouldn't be treated as a universal level for the general case.

[10]  arXiv:2002.02982 [pdf, ps, other]
Title: OAUNI astronomical photometry: Stellar variability of FO Aqr on 2016 low state
Authors: Antonio Pereyra
Comments: 6 pages, 6 figures, submitted to Journal of Physics: Conference Series
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)

This work reports a photometric monitoring of the intermediate polar cataclysmic variable star FO Aqr. This is part of the ongoing OAUNI stellar variability program. Around 1200 individual measurements (or $\sim$ 9 hrs of observations) were gathered distributed in five nights. The observation epoch was coincident with the 2016 low state brightness of FO Aqr. Good quality light curves detect unambiguously the expected stellar variability of FO~Aqr. The analysis using periodograms let to determine the main two known periods, P$_{1}$~=~20.380~$\pm$~.003~min and P$_{2}$~=~11.076~$\pm$~.001~min. Our full five-nights analysis shows that P$_{1}$, the spin white dwarf period, is more prominent than P$_{2}$, the one-half of the beat period between the spin and orbital periods. Nevertheless, individual light curves show than, at least in one case, a reverse pattern is found. It suggests a dependence of the beat period with the orbital phase of the system with important variations at the same phase interval.

[11]  arXiv:2002.02983 [pdf, other]
Title: Rocking shadows in broken circumbinary discs
Comments: 5 pages, 3 figures. Accepted for publication in MNRAS Letters. Movie of figure 1 available at this https URL
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)

We use three dimensional simulations with coupled hydrodynamics and Monte Carlo radiative transfer to show that shadows cast by the inner disc in broken circumbinary discs move within a confined range of position angles on the outer disc. Over time, shadows appear to rock back and forth in azimuth as the inner disc precesses. The effect occurs because the inner disc precesses around a vector that is not the angular momentum vector of the outer disc. We relate our findings to recent observations of shadows in discs.

[12]  arXiv:2002.02986 [pdf, other]
Title: Analytical model for cluster radio relics
Authors: M. Brüggen, F. Vazza
Comments: Accepted by MNRAS
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

Radio relics are vast synchrotron sources that sit on the outskirts of merging galaxy clusters. In this work we model their formation using a Press-Schechter formalism to simulate merger rates, analytical models for the intracluster medium and the shock dynamics, as well as a simple model for the cosmic-ray electrons at the merger shocks. We show that the statistical properties of the population of radio relics are strongly dependent on key physical parameters, such as the acceleration efficiency, the magnetic field strength at the relic, the geometry of the relic and the duration of the electron acceleration at merger shocks. It turns out that the flux distribution as well as the power-mass relation can constrain key parameters of the intracluster medium. With the advent of new large-area radio surveys, statistical analyses of radio relics will complement what we have learned from observations of individual objects.

[13]  arXiv:2002.03011 [pdf]
Title: Probability Distribution of Magnetic Field Strengths through the Cyclotron Lines in High-Mass X-ray Binaries
Comments: Accepted for publication in Jordan Journal of Physic
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

The study of variation of measured cyclotron lines is of fundamental importance to understand the physics of the accretion process in magnetized neutron star systems. We investigate the magnetic field formation, evolution and distribution for several High- Mass X-ray Binaries (HMXBs). We focus our attention on the cyclotron lines that have been detected in HMXB classes in their X-ray spectra. As has been correctly pointed out, several sources show variation in cyclotron lines, this can result due to the effect of accretion dynamics, and hence that would reflect the magnetic field characteristics. Besides, the difference in time scales of variation of accretion rate and different type of companion can be used to distinguish between magnetized neutron stars.

[14]  arXiv:2002.03033 [pdf, ps, other]
Title: On the orbital evolution of 2020 AV2, the first asteroid ever observed to go around the Sun inside the orbit of Venus
Comments: 5 pages, 5 figures, 2 tables. Accepted for publication in Monthly Notices of the Royal Astronomical Society Letters
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)

The innermost section of the Solar system has not been extensively studied because minor bodies moving inside Earth's orbit tend to spend most of their sidereal orbital periods at very low solar elongation, well away from the areas more frequently observed by programs searching for near-Earth objects. The survey carried out from the Zwicky Transient Facility (ZTF) is the first one that has been able to detect multiple asteroids well detached from the direct gravitational perturbation of the Earth-Moon system. ZTF discoveries include 2019 AQ3 and 2019 LF6, two Atiras with the shortest periods among known asteroids. Here, we perform an assessment of the orbital evolution of 2020 AV2, an Atira found by ZTF with a similarly short period but following a path contained entirely within the orbit of Venus. This property makes it the first known member of the elusive Vatira population. Genuine Vatiras, those long-term dynamically stable, are thought to be subjected to the so-called von Zeipel-Lidov-Kozai oscillation that protects them against close encounters with both Mercury and Venus. However, 2020 AV2 appears to be a former Atira that entered the Vatira orbital domain relatively recently. It displays an anti-coupled oscillation of the values of eccentricity and inclination, but the value of the argument of perihelion may circulate. Simulations show that 2020 AV2 might reach a 3:2 resonant orbit with Venus in the future, activating the von Zeipel-Lidov-Kozai mechanism, which in turn opens the possibility to the existence of a long-term stable population of Vatiras trapped in this configuration.

[15]  arXiv:2002.03086 [pdf, ps, other]
Title: Impact of an Active Sgr A* on the Synthesis of Water and Organic Molecules Throughout the Milky Way
Authors: Chang Liu (PKU), Xian Chen (PKU), Fukun Du (PMO)
Comments: 18 pages, 8 figures
Subjects: Astrophysics of Galaxies (astro-ph.GA); Instrumentation and Methods for Astrophysics (astro-ph.IM); Solar and Stellar Astrophysics (astro-ph.SR)

Sgr A*, the supermassive black hole (SMBH) in our Galaxy, is dormant today, but it should have gone through multiple gas-accretion episodes in the past to grow to its current mass of $4\times10^6\,M_\odot$. Each episode temporarily ignites the SMBH and turns the Galactic Center into an active galactic nucleus (AGN). Recently, we showed that the AGN could produce large amount of hard X-rays that can penetrate the dense interstellar medium in the Galactic plane. Here we further study the impact of the X-rays on the molecular chemistry in our Galaxy. We use a chemical reaction network to simulate the evolution of several molecular species including $\rm{H_2O}$, $\rm{CH_3OH}$, and $\rm{H_2CO}$, both in the gas phase and on the surface of dust grains. We find that the X-ray irradiation could significantly enhance the abundances of these species. The effect is the most significant in those young, high-density molecular clouds, and could be prominent at a Galactic distance of $8$ kpc or smaller. The imprint in the chemical abundance is visible even several million years after the AGN turns off. The potential impact on the origin and evolution of organic and prebiotic molecules in the Milky Way deserves further investigation.

[16]  arXiv:2002.03089 [pdf, ps, other]
Title: The First VERA Astrometry Catalog
Comments: 35 pages, 7 figures, accepted for publication in the Publications of the Astronomical Society of Japan
Subjects: Astrophysics of Galaxies (astro-ph.GA)

We present the first astrometry catalog from the Japanese VLBI (very long baseline interferometer) project VERA (VLBI Exploration of Radio Astrometry). We have compiled all the astrometry results from VERA, providing accurate trigonometric annual parallax and proper motion measurements. In total, 99 maser sources are listed in the VERA catalog. Among them, 21 maser sources are newly reported while the rest of 78 sources are referred to previously published results or those in preparation for forthcoming papers. The accuracy in the VERA astrometry are revisited and compared with those from the other VLBI astrometry projects such as BeSSeL (The Bar and Spiral Structure Legacy) Survey and GOBELINS (the Gould's Belt Distances Survey) with the VLBA (Very Long Baseline Array). We have confirmed that most of the astrometry results are consistent with each other, and the largest error sources are due to source structure of the maser features and their rapid variation, along with the systematic calibration errors and different analysis methods. Combined with the BeSSeL results, we estimate the up-to-date fundamental Galactic parameter of $R_{0}=7.92\pm0.16_{\rm{stat.}}\pm0.3_{\rm{sys.}}$~kpc and $\Omega_{\odot}=30.17\pm0.27_{\rm{stat.}}\pm0.3_{\rm{sys.}}$~km~s$^{-1}$~kpc$^{-1}$, where $R_{0}$ and $\Omega_{\odot}$ are the distance from the Sun to the Galactic center and the Sun's angular velocity of the Galactic circular rotation, respectively.

[17]  arXiv:2002.03096 [pdf, ps, other]
Title: Discovery of annular X-ray emission centered on MAXI J1421-613: Dust-scattering X-rays?
Comments: 11 pages, 3 figures, accepted for publication in Publications of the Astronomical Society of Japan (PASJ)
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

We report the discovery of an annular emission of $\sim$3'-9' radius around the center of a transient source, an X-ray burster MAXI J1421-613, in the Suzaku follow-up analysis. The spectrum of the annular emission shows no significant emission-line structure, and is well explained by an absorbed power law model with a photon index of $\sim$4.2. These features exclude the possibility that the annular emission is a shell-like component of a supernova remnant. The spectral shape, the time history, and the X-ray flux of the annular emission agree with the scenario that the emission is due to a dust-scattering echo. The annular emission is made under a rare condition of the dust-scattering echo, where the central X-ray source, MAXI J1421-613, exhibits a short time outburst with three X-ray bursts and immediately re-enters a long quiescent period. The distribution of the hydrogen column density along the annular emission follows that of the CO intensity, which means that MAXI J1421-613 is located behind the CO cloud. We estimate the distance to MAXI J1421-613 to be $\sim$3~kpc assuming that the dust layer responsible for the annular emission is located at the same position as the CO cloud.

[18]  arXiv:2002.03100 [pdf, other]
Title: Studies of Evolved Stars in the Next Decade: EAO Submillimetre Futures White Paper Series, 2019
Comments: 11 pages, 2 figures; Part of the 2019 EAO Submillimetre Futures Paper Series, this https URL
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)

This white paper discusses recent progress in the field of evolved stars, primarily highlighting the contributions of the James Clerk Maxwell Telescope. It discusses the ongoing project, the \emph{Nearby Evolved Stars Survey} (NESS), and the potential to build upon NESS in the next decade. It then outlines a number of science cases which may become feasible with the proposed 850\,$\mu$m camera which is due to become available at the JCMT in late 2022. These include mapping the extended envelopes of evolved stars, including in polarisation, and time-domain monitoring of their variations. The improved sensitivity of the proposed instrument will facilitate statistical studies that put the morphology, polarisation properties and sub-mm variability in perspective with a relatively modest commitment of time that would be impossible with current instrumentation. We also consider the role that could be played by other continuum wavelengths, heterodyne instruments or other facilities in contributing towards these objectives.

[19]  arXiv:2002.03110 [pdf, other]
Title: Entropy and Mass Distribution in Disc Galaxies
Comments: 16 pages, 4 figures. Invitation paper for "Debate on the Physics of Galactic Rotation and the Existence of Dark Matter". Accepted Jan 2020
Journal-ref: Galaxies 2020, 8, 12
Subjects: Astrophysics of Galaxies (astro-ph.GA)

The relaxed motion of stars and gas in galactic discs is well approximated by a rotational velocity that is a function of radial position only, implying that individual components have lost any information about their prior states. Thermodynamically, such an equilibrium state is a microcanonical ensemble with maximum entropy, characterised by a lognormal probability distribution. Assuming this for the surface density distribution yields rotation curves that closely match observational data across a wide range of disc masses and galaxy types, and provides a useful tool for modelling the theoretical density distribution in the disc. A universal disc spin parameter emerges from the model, giving a tight virial mass estimator with strong correlation between angular momentum and disc mass, suggesting a mechanism by which the proto-disc developed by dumping excess mass to the core, or excess angular momentum to a satellite galaxy. The baryonic-to-dynamic mass ratio for the model approaches unity for high mass galaxies, but is generally $<1$ for low mass discs, and this discrepancy appears to follow a similar relationship to that shown in recent work on the radial acceleration relation (RAR). Although this may support Modified Newtonian Dynamics (MOND) in preference to a dark matter (DM) halo, it does not exclude undetected baryonic mass or a gravitational DM component in the disc.

[20]  arXiv:2002.03115 [pdf, other]
Title: Rapid grain growth in post-AGB disc systems from far-infrared and sub-millimetre photometry
Comments: 13 pages, 7 figures. Accepted for publication in MNRAS
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)

The timescales on which astronomical dust grows remain poorly understood, with important consequences for our understanding of processes like circumstellar disk evolution and planet formation.A number of post-asymptotic giant branch stars are found to host optically thick, dust- and gas-rich circumstellar discs in Keplerian orbits. These discs exhibit evidence of dust evolution, similar to protoplanetary discs; however since post-AGB discs have substantially shorter lifetimes than protoplanetary discs they may provide new insights on the grain-growth process. We examine a sample of post-AGB stars with discs to determine the FIR and sub-mm spectral index by homogeneously fitting a sample of data from \textit{Herschel}, the SMA and the literature. We find that grain growth to at least hundreds of micrometres is ubiquitous in these systems, and that the distribution of spectral indices is more similar to that of protoplanetary discs than debris discs. No correlation is found with the mid-infrared colours of the discs, implying that grain growth occurs independently of the disc structure in post-AGB discs. We infer that grain growth to $\sim$mm sizes must occur on timescales $<<10^{5}$ yr, perhaps by orders of magnitude, as the lifetimes of these discs are expected to be $\lesssim10^{5}$~yr and all objects have converged to the same state. This growth timescale is short compared to the results of models for protoplanetary discs including fragmentation, and may provide new constraints on the physics of grain growth.

[21]  arXiv:2002.03204 [pdf, other]
Title: Evolution of porous dust grains in protoplanetary discs -- I. Growing grains
Comments: Accepted for publication in MNRAS. 13 pages, 13 figures
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)

One of the main problems in planet formation, hampering the growth of small dust to planetesimals, is the so-called radial-drift barrier. Pebbles of cm to dm sizes are thought to drift radially across protoplanetary discs faster than they can grow to larger sizes, and thus to be lost to the star. To overcome this barrier, drift has to be slowed down or stopped, or growth needs to be sped up. In this paper, we investigate the role of porosity on both drift and growth. We have developed a model for porosity evolution during grain growth and applied it to numerical simulations of protoplanetary discs. We find that growth is faster for porous grains, enabling them to transition to the Stokes drag regime, decouple from the gas, and survive the radial-drift barrier. Direct formation of small planetesimals from porous dust is possible over large areas of the disc.

[22]  arXiv:2002.03210 [pdf, other]
Title: Measuring Nuclear Matter Parameters with NICER and LIGO/Virgo
Authors: Josef Zimmerman (1), Zack Carson (1), Kristen Schumacher (2), Andrew W. Steiner (3 and 4), Kent Yagi (1) ((1) University of Virginia, (2) University of Illinois at Urbana-Champaign, (3) University of Tennessee, (4) Oak Ridge National Laboratory)
Comments: 6 pages, 4 figures
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc); Nuclear Theory (nucl-th)

The NICER Collaboration recently reported the measurement of the mass and radius of a pulsar PSR J0030+0451. We here use this new measurement to constrain one of the higher-order nuclear matter parameters $K_{\mathrm{sym,0}}$. We further combine the tidal measurement of the binary neutron star merger GW170817 by LIGO/Virgo to derive a joint 1-$\sigma$ constraint as $K_{\mathrm{sym,0}} = -102^{+71}_{-72}$ MeV. We believe this is the most reliable bound on the parameter to date under the assumption that there is no new physics above the saturation density which impacts neutron star observations.

[23]  arXiv:2002.03247 [pdf, other]
Title: Propulsion of Spacecrafts to Relativistic Speeds Using Natural Astrophysical Sources
Comments: 16 pages; 3 figures; submitted for publication
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Earth and Planetary Astrophysics (astro-ph.EP); High Energy Astrophysical Phenomena (astro-ph.HE); Space Physics (physics.space-ph)

In this paper, we explore the possibility of using natural astrophysical sources to accelerate spacecrafts to relativistic speeds. We focus on light sails and electric sails, which are reliant on momentum transfer from photons and protons, respectively, because these two classes of spacecrafts are not required to carry fuel on board. The payload is assumed to be stationed near the astrophysical source, and the sail is subsequently unfolded and activated when the source is functional. By considering a number of astrophysical objects such as massive stars, microquasars, supernovae, pulsar wind nebulae, and active galactic nuclei, we show that speeds approaching the speed of light might be realizable under broad circumstances. We also investigate the constraints arising from the ambient source environment as well as during the passage through the interstellar medium. While both of these considerations pose significant challenges to spacecrafts, we estimate that they are not insurmountable. Finally, we sketch the implications for carrying out future searches for technosignatures.

[24]  arXiv:2002.03248 [pdf, other]
Title: Implications of Abiotic Oxygen Buildup for Earth-like Complex Life
Authors: Manasvi Lingam
Comments: Accepted for publication in The Astronomical Journal; 9 pages; 2 figures
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR); Populations and Evolution (q-bio.PE)

One of the chief paradoxes of molecular oxygen (O$_2$) is that it is an essential requirement for multicellular eukaryotes on Earth while simultaneously posing a threat to their survival via the formation of reactive oxygen species. In this paper, the constraints imposed by O$_2$ on Earth-like complex life are invoked to explore whether worlds with abiotic O$_2$ inventories can harbor such organisms. By taking the major O$_2$ sources and sinks of Earth-like planets into account using a simple model, it is suggested that worlds that receive X-ray and extreme ultraviolet fluxes that are $\gtrsim 10$ times higher than Earth might not be capable of hosting complex lifeforms because the photolysis of molecules such as water may lead to significant O$_2$ buildup. Methods for testing this hypothesis by searching for anticorrelations between biosignatures and indicators of abiotic O$_2$ atmospheres are described. In the event, however, that life successfully adapts to high-oxygen environments, these worlds could permit the evolution of large and complex organisms.

[25]  arXiv:2002.03270 [pdf, ps, other]
Title: Propagating Slow Sausage Waves in a Sunspot Observed by the New Vacuum Solar Telescope
Comments: 8 pages, 6 figures,1 table
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)

A sunspot is an ideal waveguide for a variety of magnetohydrodynamic waves, which carry a significant amount of energy to the upper atmosphere and could be used as a tool to probe magnetic and thermal structure of a sunspot. In this study, we used the New Vacuum Solar Telescope and took high-resolution image sequences simultaneously in both TiO (7058$\pm$10 \AA) and H$_\alpha$ (6562$\pm$2.5 \AA) bandpasses. We extracted the area and total emission intensity variations of sunspot umbra and analyzed the signals with synchrosqueezing transform. We found that the area and emission intensity varied with both three and five minute periodicity. Moreover, the area and intensity oscillated in phase with each other, this fact hold in both TiO and H$_\alpha$ data. We interpret this oscillatory signal as propagating slow sausage wave. The propagation speed is estimated at about 8 km$\cdot$s$^{-1}$. We infer that this sunspot's umbra could have temperature as low as 2800--3500 K.

[26]  arXiv:2002.03275 [pdf, ps, other]
Title: Comparative intra-night optical variability of X-ray and $γ$-ray detected narrow-line Seyfert 1 galaxies
Comments: Accepted for publication in MNRAS. This manuscript consists of 14 pages including 7 figures, 3 tables in the paper and two tables in the appendix
Subjects: Astrophysics of Galaxies (astro-ph.GA); High Energy Astrophysical Phenomena (astro-ph.HE)

In a systematic program to characterise the intra-night optical variability (INOV) of different classes of narrow-line Seyfert 1 galaxies (NLSy1s), we report here the first comparative INOV study of NLSy1 sets detected in the X-ray and $\gamma$-ray bands. Our sample consists of 18 sources detected in X-ray but not in $\gamma$-rays (hereafter x$\textunderscore$NLSy1s) and 7 sources detected in $\gamma$-rays (hereafter g$\textunderscore$NLSy1s), out of which 5 are detected also in X-rays. We have monitored these two sets of NLSy1s, respectively, in 24 and 21 sessions of a minimum of 3 hours duration each. The INOV duty cycles for these two sets are found to be 12\% and 53\%, respectively (at a 99\% confidence level). In the set of 18 x$\textunderscore$NLSy1s, INOV duty cycle is found to be zero for the 13 radio-quiet members (monitored in 14 sessions) and 43\% for the 5 radio-loud members (10 sessions). The latter is very similar to the aforementioned duty cycle of 53\% found here for the set of g$\textunderscore$NLSy1s (all of which are radio-loud). Thus it appears that the radio loudness level is the prime factor behind the INOV detection and the pattern of the high-energy radiation plays only a minor role.

[27]  arXiv:2002.03300 [pdf, ps, other]
Title: A New Approach to Mass and Radius of Neutron Stars with Supernova Neutrinos
Comments: 5 pages, 5 figures, 10 symmetry energies, 30 MR relations, 90 EOSs, 360 PNS cooling models
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Phenomenology (hep-ph); Nuclear Theory (nucl-th)

Neutron stars are formed in core-collapse supernova explosions, where a large number of neutrinos are emitted. In this paper, supernova neutrino light curves are computed for the cooling phase of protoneutron stars, which lasts a few minutes. In the numerical simulations, 90 models of the phenomenological equation of state with different incompressibilities, symmetry energies, and nucleon effective masses are employed for a comprehensive study. It is found that the cooling timescale is longer for a model with a larger neutron star mass and a smaller neutron star radius. Furthermore, a theoretical expression of the cooling timescale is presented as a function of the mass and radius and it is found to describe the numerical results faithfully. These findings suggest that diagnosing the mass and radius of a newly formed neutron star using its neutrino signal is possible.

[28]  arXiv:2002.03315 [pdf, other]
Title: A detailed study on the reflection component for the Black Hole Candidate MAXI J1836-194
Comments: Accepted for publication in MNRAS
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

We present a detailed spectral analysis of the black hole candidate MAXI J1836-194. The source was caught in the intermediate state during its 2011 outburst by Suzaku and RXTE. We jointly fit the X-ray data from these two missions using the relxill model to study the reflection component, and a steep inner emissivity profile indicating a compact corona as the primary source is required in order to achieve a good fit. In addition, a reflection model with a lamp-post configuration (relxilllp), which is normally invoked to explain the steep emissivity profile, gives a worse fit and is excluded at 99% confidence level compared to relxill. We also explore the effect of the ionization gradient on the emissivity profile by fitting the data with two relativistic reflection components, and it is found that the inner emissivity flattens. These results may indicate that the ionization state of the disc is not constant. All the models above require a supersolar iron abundance higher than 4.5. However, we find that the high-density version of reflionx can describe the same spectra even with solar iron abundance well. A moderate rotating black hole (a* = 0.84-0.94) is consistently obtained by our models, which is in agreement with previously reported values.

[29]  arXiv:2002.03316 [pdf, ps, other]
Title: Constraining Einstein's Equivalence Principle With Multi-Wavelength Observations of Polarized Blazars
Comments: 16 pages, 5 figures, 2 tables, accepted for publication in MNRAS
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

In this paper, we present a novel method to test the Einstein's Equivalence Principle (EEP) using (simultaneous) multi-wavelength radio observations of polarized blazars. We analyze simultaneous multi-wavelength polarization observations of 3C 279 at 22, 43, and 86 GHz obtained by two antennas of the Korean VLBI Network. We obtained 15 groups of polarization data, and applied the Metropolis-Hastings Markov Chain (MHMC) to simulate the parameters when considering the EEP effect and the simplest form of Faraday rotation (single external Faraday screen). The final results show the constraint of the parameterized post-Newtonian (PPN) parameter $\gamma$ discrepancy as $\Delta \gamma_{p} = (1.91\pm0.34)\times10^{-20}$. However, the single external Faraday screen is an oversimplification for blazars because there are numerous observations show complex Faraday rotation behavior for blazars due to internal/external Faraday dispersion, beam depolarization, etc. The value $\Delta \gamma_{p}$ results of this paper can only be considered as upper limits. Only if all other effects are revealed and considered, should the result be taken as a direct measurement of the violation of the EEP.

[30]  arXiv:2002.03354 [pdf, other]
Title: Automatic removal of false image stars in disk-resolved images of the Cassini Imaging Science Subsystem
Comments: 13 pages, 11 figures, accepted by Research in Astronomy and Astrophysics (RAA)
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)

Taking a large amount of images, the Cassini Imaging Science Subsystem (ISS) has been routinely used in astrometry. In ISS images, disk-resolved objects often lead to false detection of stars that disturb the camera pointing correction. The aim of this study was to develop an automated processing method to remove the false image stars in disk-resolved objects in ISS images. The method included the following steps: extracting edges, segmenting boundary arcs, fitting circles and excluding false image stars. The proposed method was tested using 200 ISS images. Preliminary experimental results show that it can remove the false image stars in more than 95% of ISS images with disk-resolved objects in a fully automatic manner, i.e. outperforming the traditional circle detection based on Circular Hough Transform (CHT) by 17%. In addition, its speed is more than twice as fast as that of the CHT method. It is also more robust (no manual parameter tuning is needed) when compared with CHT. The proposed method was also applied to a set of ISS images of Rhea to eliminate the mismatch in pointing correction in automatic procedure. Experiment results showed that the precision of final astrometry results can be improve by roughly 2 times than that of automatic procedure without the method. It proved that the proposed method is helpful in the astrometry of ISS images in fully automatic manner.

[31]  arXiv:2002.03380 [pdf, other]
Title: Probing Dark Matter with Future CMB Measurements
Comments: 9 pages, 4 figures, 2 tables
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph)

Dark Matter (DM) annihilation and decay during the Dark Ages can affect the cosmic ionization history and leave imprints in the Cosmic Microwave Background (CMB) anisotropy spectra. CMB polarization anisotropy can be sensitive to such energy injection at higher redshifts and help reducing degeneracy with primordial spectral parameters in $\Lambda$CDM and astrophysical ionization processes during reionization. In light of a number of upcoming CMB polarization experiments, such as AdvACTPol, AliCPT, CLASS, Simons Observatory, Simons Array, SPT-3G, we estimate their prospective sensitivity in probing dark matter annihilation and decay signals. We find that future missions have 95\% C.L. projected limits on DM decay and annihilation rates to orders of $\Gamma_\chi (\tau_{\chi}^{-1}) \sim 10^{-27}{\rm{s}}^{-1}$ and $\left<\sigma v \right>/m_{\chi} \sim 10^{-29}{\rm{cm^3s^{-1}GeV^{-1}}}$ respectively, significantly improving the sensitivity to DM from current experimental bounds.

[32]  arXiv:2002.03390 [pdf, other]
Title: Rotational Disruption of Dust and Ice by Radiative Torques in Protoplanetary Disks and Implications for Observations
Comments: 22 pages, 18 figures, to be submitted; comments welcome
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)

Dust and ice mantles on dust grains play an important role in various processes in protoplanetary disks (PPDs) around a young star, including planetesimal formation, surface chemistry, and being the reservoir of water in habitable zones. In this paper, we will perform two-dimensional modeling of rotational disruption of dust grains and ice mantles due to centrifugal force within suprathermally rotating grains spun-up by radiative torques for disks around T-Tauri and Herbig Ae/Be stars. We first study rotational disruption of large composite grains and find that large aggregates could be disrupted into individual nanoparticles via the RAdiative Torque Disruption (RATD) mechanism. We then study rotational desorption of ice mantles and ro-thermal desorption of molecules from the ice mantle. We will show that ice mantles in the warm surface layer and above of the disk can be disrupted into small icy fragments, followed by rapid evaporation of molecules. We suggest that the rotational disruption mechanism can replenish the ubiquitous presence of polycyclic aromatic hydrogen (PAHs)/ nanoparticles in the hot surface layers of PPDs as observed in mid-IR emission, which are presumably destroyed by extreme ultraviolet (UV) stellar photons. We show that the water snowline is more extended in the presence of rotational desorption, which would decrease the number of gaseous planets and comets but increase the number of rocky planets and asteroids formed in the solar nebula. Finally, we suggest that the more efficient breakup of carbonaceous grains than silicates by RATD might resolve the carbon deficit problem measured on the Earth and rocky bodies.

[33]  arXiv:2002.03408 [pdf, other]
Title: Nonlinear interacting cosmological models after Planck 2018 legacy release and the $H_0$ tension
Comments: 22 pages, 4 Tables, 19 captioned figures; Accepted for publication by MNRAS
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc)

Interacting dark energy models are widely renowned for giving an explanation to the cosmic coincidence problem as well as several observational issues. According to the recent observational data, and so far we are concerned with the literature, the choice of the interaction function between dark matter and dark energy is always questionable since there is no such underlying theory that could derive it. Thus, in this work we have raised this issue by proposing two new nonlinear interaction functions and constrain them using cosmic microwave background (CMB) from Planck 2018, baryon acoustic oscillations (BAO), dark energy survey and a measurement of the Hubble constant $H_0$ from Hubble Space Telescope (HST) 2019. The dark energy equation of state is considered to be constant throughout the work and the geometry of the universe is assumed to be homogeneous and isotropic with zero spatial curvature. Our analyses report that a non-zero interaction is always allowed by the observational data and the dark energy equation of state is bent towards the phantom regime. In particular, when $H_0$ from HST is added to Planck 2018+BAO, we find an evidence for a non-zero coupling at more than $2\sigma$ confidence level. Our analyses also report that for both the models, $H_0$ is close to its local measurements and thus alleviating the $H_0$ tension. In particular, one of the interacting models perfectly solves the $H_0$ tension.

[34]  arXiv:2002.03442 [pdf, other]
Title: On the Origin of the Globular Cluster FSR 1758
Authors: Fu Chi Yeh (UniPD), Giovanni Carraro (UniPD), Vladimir Korchagin (Southern Federal University), Camilla Pianta (UniPD), Sergio Ortolani (UniPD)
Comments: 8 pages, 3 figures, accepted for publication in Astronomy and Astrophysics
Subjects: Astrophysics of Galaxies (astro-ph.GA)

Globular clusters in the Milky Way are thought to have either an {\it in situ} origin, or to have been deposited in the Galaxy by past accretion events, like the spectacular Sagittarius dwarf galaxy merger. We aim to probe the origin of the recently discovered globular cluster FSR 1758, often associated with some past merger event, and which happens to be projected toward the Galactic bulge, by a detailed study of its Galactic orbit, and to assign it to the most suitable Galactic component. We employ three different analytical time-independent potential models to calculate the orbit of the cluster by using the Gauss Radau spacings integration method. In addition, a time-dependent bar potential model is added to account for the influence of the Galactic bar. We run a large suite of simulations to account for the uncertainties in the initial conditions, in a Montecarlo fashion. We confirm previous indications that the globular cluster FSR 1758 possesses a retrograde orbits with high eccentricity. The comparative analysis of the orbital parameters of star clusters in the Milky Way, in tandem with recent metallicity estimates, allows us to conclude that FSR1758 is indeed a Galactic bulge intruder. The cluster can therefore be considered an old metal poor halo globular cluster formed {\it in situ} and which is passing right now in the bulge region. Its properties, however, can be roughly accounted for also assuming that the cluster is part of some stream of extra-Galactic origin. We conclude that assessing the origin, either Galactic or extra-galactic, of globular clusters is surely a tantalising task. In any case, by using an {\it Occam's razor} argument, we tend to prefer an {\it in situ} origin for FSR 1758.

[35]  arXiv:2002.03446 [pdf, other]
Title: Identification of filamentary structures in the environment of superclusters of galaxies in the Local Universe
Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)

The characterization of the internal structure of the superclusters of galaxies (walls, filaments and knots where the clusters are located) is paramount for understanding the formation of the Large Scale Structure and for outlining the environment where galaxies evolved in the last Gyr. (i) To detect the compact regions of high relative density (clusters and rich groups of galaxies); (ii) to map the elongated structures of low relative density (filaments, bridges and tendrils of galaxies); (iii) to characterize the galaxy populations on filaments and study the environmental effects they are subject to. We employed optical galaxies with spectroscopic redshifts from the SDSS-DR13 inside rectangular boxes encompassing the volumes of a sample of 46 superclusters of galaxies, up to z=0.15. Our methodology implements different classical pattern recognition and machine learning techniques pipelined in the Galaxy Systems-Finding algorithm and the Galaxy Filaments-Finding algorithm. We detected in total 2,705 galaxy systems (clusters and groups, of which 159 are new) and 144 galaxy filaments in the 46 superclusters of galaxies. The filaments we detected have a density contrast above 3, with a mean value around 10, a radius of about 2.5 Mpc and lengths between 9 and 130 Mpc. Correlations between the galaxy properties (mass, morphology and activity) and the environment in which they reside (systems, filaments and the dispersed component) suggest that galaxies closer to the skeleton of the filaments are more massive by up to 25% compared to those in the dispersed component; 70 % of the galaxies in the filament region present early type morphologies and the fractions of active galaxies (both AGN and SF) seem to decrease as galaxies approach the filament. These results suggest that preprocessing in large scale filaments could have significant effects on galaxy evolution.

[36]  arXiv:2002.03453 [pdf, other]
Title: On the peculiar torque reversals and the X-ray luminosity history of the accretion-powered X-ray pulsar 4U 1626--67
Authors: Onur Benli
Comments: Submitted to MNRAS. Comments are welcome!
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

We have investigated the rotational and the X-ray luminosity ($L_{\mathrm{x}}$) observations of 4U 1626--67 accumulated during the last four decades. It has been recorded that the source underwent a torque reversal twice. We have tried to understand whether this eccentrical sign-switch of the period derivative ($\dot{P}$) of the source could be accounted for with the existing torque models. We have found that the observed source properties are better estimated with the distances close to the lower limit of the previously predicted distance range ($5-13$ kpc). Furthermore, assuming an inclined rotator, we have considered the partial accretion/ejection from the co-rotation radius that leads different $L_{\mathrm{x}}$-$\dot{P}$ profiles than the aligned rotator cases. We have concluded that the oblique rotator assumption brings at least equally best fitting to the observed X-ray luminosity and the rotational properties of 4U 1626--67. More importantly, the estimated change of the mass accretion rate which causes the change in observed $L_{\mathrm{x}}$ of 4U 1626--67 is much less than that is found in an aligned rotator case. In other words, without the need for a substantial modification of mass accretion rate from the companion star, the range of the observed X-ray luminosity could be explained naturally with an inclined magnetic axis and rotation axis of the neutron star.

[37]  arXiv:2002.03455 [pdf, ps, other]
Title: Rotation periods from the inflection point in the power spectrum of stellar brightness variations: II. The Sun
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)

Young and active stars generally have regular, almost sinusoidal, patterns of variability attributed to their rotation, while the majority of older and less active stars, including the Sun, have more complex and non-regular light-curves which do not have clear rotational-modulation signals. Consequently, the rotation periods have been successfully determined only for a small fraction of the Sun-like stars observed by transit-based planet-hunting missions, such as CoRoT, Kepler, and TESS. This suggests that only a small fraction of such systems have been properly identified as solar-like analogs. We apply a new method for determining rotation periods of low-activity stars, like the Sun. The method is based on calculating the gradient of the power spectrum (GPS) of stellar brightness variations and identifying a tell-tale inflection point in the spectrum. The rotation frequency is then proportional to the frequency of that inflection point. In this paper test this GPS method against available photometric records of the Sun. We apply GPS, autocorrelation functions, Lomb-Scargle periodograms, and wavelet analyses to the total solar irradiance (TSI) time series obtained from the Total Irradiance Monitor (TIM) on the Solar Radiation and Climate Experiment (SORCE) and the Variability of solar IRradiance and Gravity Oscillations (VIRGO) experiment on the SOlar and Heliospheric Observatory (SoHO) missions. We analyse the performance of all methods at various levels of solar activity. We show that the GPS method returns accurate values of solar rotation independently of the level of solar activity. In particular, it performs well during periods of high solar activity, when TSI variability displays an irregular pattern and other methods fail. Our results suggest that the GPS method can successfully determine the rotational periods of stars with both regular and non-regular light-curves.

[38]  arXiv:2002.03506 [pdf, ps, other]
Title: Searching for Galactic Micro-FRB with Lunar Scattering
Authors: J. I. Katz
Comments: 4 pp., 2 figs
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Instrumentation and Methods for Astrophysics (astro-ph.IM)

Does the Galaxy contain sources of micro-FRB? The answer to this question is essential to determining the nature of FRB sources. At typical ($10$ kpc) Galactic distances a burst would be about 117 dB brighter than at a ``cosmological'' ($z = 1$) distance. Even very low energy Galactic micro-FRB would be detectable, if they exist, or a useful upper bound on their rate set, by a modest (20 m at 1.4 GHz) radio telescope staring at the Moon to detect their reflected radiation. Such a system would have all-sky sensitivity to FRB. The interval between detection of direct and Lunar-scattered radiation would restrict a burst's position to a narrow arc.

[39]  arXiv:2002.03507 [pdf, other]
Title: Fast radio bursts from activities of neutron stars newborn in BNS mergers: offset, birth rate and observational properties
Comments: 29 pages, 9 figures, accepted for publication in ApJ
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

Young neutron stars (NSs) born in core-collapse explosions are promising candidates for the central engines of fast radio bursts (FRBs), since the first localized repeating burst FRB 121102 happens in a star forming dwarf galaxy, which is similar to the host galaxies of superluminous supernovae (SLSNe) and long gamma-ray bursts (LGRBs). However, FRB 180924 and FRB 190523 are localized to massive galaxies with low rates of star formation, compared with the host of FRB 121102. Meanwhile, the offsets between the bursts and host centers are about 4 kpc and 29 kpc for FRB 180924 and FRB 190523, respectively. These properties of hosts are similar to short gamma-ray bursts \textbf{(SGRBs)}, which are produced by mergers of binary neutron star (BNS) or neutron star-black hole (NS-BH). Therefore, the NSs powering FRBs may be formed in BNS mergers. In this paper, we study the BNS merger rates, merger times, and predict their most likely merger locations for different types of host galaxies using population synthesis method. We find that the BNS merger channel is consistent with the recently reported offsets of FRB 180924 and FRB 190523. The offset distribution of short GRBs is well reproduced by population synthesis using galaxy model which is similar to GRB hosts. The event rate of FRBs (including non-repeating and repeating), is larger than those of BNS merger and short GRBs, which requires a large fraction of observed FRBs emitting several bursts. Using curvature radiation by bunches in NS magnetospheres, we also predict the observational properties of FRBs from BNS mergers, including the dispersion measure, and rotation measure. At late times ($t\geq1$yr), the contribution to dispersion measure and rotation measure from BNS merger ejecta could be neglected.

[40]  arXiv:2002.03545 [pdf, other]
Title: Extended H$α$ over compact far-infrared continuum in dusty submillimeter galaxies -- Insights into dust distributions and star-formation rates at $z\sim2$
Comments: 15 pages, 8 figures, A&A in press
Subjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)

Using data from ALMA and near-infrared (NIR) integral field spectrographs including both SINFONI and KMOS on the VLT, we investigate the two-dimensional distributions of H$\alpha$ and rest-frame far-infrared (FIR) continuum in six submillimeter galaxies at $z\sim2$. At a similar spatial resolution ($\sim$0.5" FWHM; $\sim$4.5 kpc at $z=2$), we find that the half-light radius of H$\alpha$ is significantly larger than that of the FIR continuum in half of the sample, and on average H$\alpha$ is a median factor of $2.0\pm0.4$ larger. Having explored various ways to correct for the attenuation, we find that the attenuation-corrected H$\alpha$-based SFRs are systematically lower than the IR-based SFRs by at least a median factor of $3\pm1$, which cannot be explained by the difference in half-light radius alone. In addition, we find that in 40% of cases the total $V$-band attenuation ($A_V$) derived from energy balance modeling of the full ultraviolet(UV)-to-FIR spectral energy distributions (SEDs) is significantly higher than that derived from SED modeling using only the UV-to-NIR part of the SEDs, and the discrepancy appears to increase with increasing total infrared luminosity. Finally, considering all our findings along with the studies in the literature, we postulate that the dust distributions in SMGs, and possibly also in less IR luminous $z\sim2$ massive star-forming galaxies, can be decomposed into three main components; the diffuse dust heated by older stellar populations, the more obscured and extended young star-forming HII regions, and the heavily obscured central regions that have a low filling factor but dominate the infrared luminosity in which the majority of attenuation cannot be probed via UV-to-NIR emissions.

[41]  arXiv:2002.03567 [pdf, other]
Title: The Great Markarian 421 Flare of February 2010: Multiwavelength variability and correlation studies
Comments: 41 pages including 3 appendices, 13 figures; version accepted to Astrophysical Journal
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

We report on variability and correlation studies using multiwavelength observations of the blazar Mrk 421 during the month of February, 2010 when an extraordinary flare reaching a level of $\sim$27~Crab Units above 1~TeV was measured in very-high-energy (VHE) $\gamma$-rays with the VERITAS observatory. This is the highest flux state for Mrk 421 ever observed in VHE $\gamma$-rays. Data are analyzed from a coordinated campaign across multiple instruments including VHE $\gamma$-ray (VERITAS, MAGIC), high-energy (HE) $\gamma$-ray (Fermi-LAT), X-ray (Swift}, RXTE, MAXI), optical (including the GASP-WEBT collaboration and polarization data) and radio (Mets\"ahovi, OVRO, UMRAO). Light curves are produced spanning multiple days before and after the peak of the VHE flare, including over several flare `decline' epochs. The main flare statistics allow 2-minute time bins to be constructed in both the VHE and optical bands enabling a cross-correlation analysis that shows evidence for an optical lag of $\sim$25-55 minutes, the first time-lagged correlation between these bands reported on such short timescales. Limits on the Doppler factor ($\delta \gtrsim 33$) and the size of the emission region ($ \delta^{-1}R_B \lesssim 3.8\times 10^{13}\,\,\mbox{cm}$) are obtained from the fast variability observed by VERITAS during the main flare. Analysis of 10-minute-binned VHE and X-ray data over the decline epochs shows an extraordinary range of behavior in the flux-flux relationship: from linear to quadratic to lack of correlation to anti-correlation. Taken together, these detailed observations of an unprecedented flare seen in Mrk 421 are difficult to explain by the classic single-zone synchrotron self-Compton model.

[42]  arXiv:2002.03572 [pdf, other]
Title: Determination of miscalibrated polarization angles from observed CMB and foreground $EB$ power spectra: Application to partial-sky observation
Authors: Yuto Minami
Comments: 13 pages, 2 figures, 4 tables
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)

We study a strategy to determine miscalibrated polarization angles of cosmic microwave background (CMB) experiments using the observed $EB$ polarization power spectra of CMB and Galactic foreground emission. We apply the methodology of Minami et al.(2019) developed for full-sky observations to ground-based experiments such as Simons Observatory. We take into account the $E$-to-$B$ leakage and $\ell$-to-$\ell$ covariance due to partial sky coverage using the public code NaMaster. We show that our method yields an unbiased estimate of miscalibrated angles. Our method also enables simultaneous determination of miscalibrated angles and the intrinsic $EB$ power spectrum of polarized dust emission when the latter is proportional to $\sqrt{C_\ell^{EE}C_\ell^{BB}}$ and $C_\ell^{BB}$ is proportional to $C_\ell^{EE}$.

[43]  arXiv:2002.03578 [pdf, other]
Title: Predicting star formation properties of galaxies using deep learning
Comments: 9 pages, 13 figures, 3 Tables, Accepted for publication in MNRAS
Subjects: Astrophysics of Galaxies (astro-ph.GA); Machine Learning (cs.LG)

Understanding the star-formation properties of galaxies as a function of cosmic epoch is a critical exercise in studies of galaxy evolution. Traditionally, stellar population synthesis models have been used to obtain best fit parameters that characterise star formation in galaxies. As multiband flux measurements become available for thousands of galaxies, an alternative approach to characterising star formation using machine learning becomes feasible. In this work, we present the use of deep learning techniques to predict three important star formation properties -- stellar mass, star formation rate and dust luminosity. We characterise the performance of our deep learning models through comparisons with outputs from a standard stellar population synthesis code.

[44]  arXiv:2002.03589 [pdf, other]
Title: In-flight performance of the LEKIDs of the OLIMPO experiment
Journal-ref: Journal of Low Temperature Physics 2020
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Instrumentation and Detectors (physics.ins-det)

We describe the in-flight performance of the horn-coupled Lumped Element Kinetic Inductance Detector arrays of the balloon-borne OLIMPO experiment. These arrays have been designed to match the spectral bands of OLIMPO: 150, 250, 350, and 460 GHz, and they have been operated at 0.3 K and at an altitude of 37.8 km during the stratospheric flight of the OLIMPO payload, in Summer 2018. During the first hours of flight, we tuned the detectors and verified their large dynamics under the radiative background variations due to elevation increase of the telescope and to the insertion of the plug-in room-temperature differential Fourier transform spectrometer into the optical chain. We have found that the detector noise equivalent powers are close to be photon-noise limited and lower than those measured on the ground. Moreover, the data contamination due to primary cosmic rays hitting the arrays is less than 3% for all the pixels of all the arrays, and less than 1% for most of the pixels. These results can be considered the first step of KID technology validation in a representative space environment.

[45]  arXiv:2002.03610 [pdf, other]
Title: A census of the near-by Pisces-Eridanus stellar stream -- Commonalities with and disparities from the Pleiades
Comments: 10 pages, 6 figures
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)

Within a 400~pc sphere around the Sun, we search for members of the Pisces-Eridanus (Psc-Eri) stellar stream in the Gaia Data Release 2 (DR2) data set. We compare basic astrophysical characteristics of the stream with those of the Pleiades. We used a modified convergent-point method to identify stars with 2D - velocities consistent with the space velocity of the Psc-Eri stream and the Pleiades, respectively. We found 1387 members of the Psc-Eri stream in a G magnitude range from 5.1 mag to 19.3 mag at distances between 80 and 380 pc from the Sun. The stream has a nearly cylindrical shape with length and thickness of about 700 pc and 100 pc, respectively. The total stellar mass contained in the stream is about 770 M_Sun, and the members are gravitationally unbound. For the stream we found an age of about 135 Myr. In many astrophysical properties Psc-Eri is comparable to the open cluster M45 (the Pleiades): in its age, its luminosity function (LF), its Present-day mass Function (PDMF) as well as in its total mass. Nonetheless, the two stellar ensembles are completely unlike in their physical appearance. We cautiously give two possible explanations for this disagreement: (i) the star-formation efficiency in their parental molecular clouds was higher for the Pleiades than for Psc-Eri or/and (ii) the Pleiades had a higher primordial mass segregation immediately after the expulsion of the molecular gas of the parental cloud.

[46]  arXiv:2002.03623 [pdf, other]
Title: Radiation hydrodynamics in simulations of the solar atmosphere
Authors: Jorrit Leenaarts
Comments: Accepted for publications in Living Reviews in Solar Physics
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)

Nearly all energy generated by fusion in the solar core is ultimately radiated away into space in the solar atmosphere, while the remaining energy is carried away in the form of neutrinos. The exchange of energy between the solar gas and the radiation field is thus an essential ingredient of atmospheric modeling. The equations describing these interactions are known, but their solution is so computationally expensive that they can only be solved in approximate form in multi-dimensional radiation-MHD modeling. In this review, I discuss the most commonly used approximations for energy exchange between gas and radiation in the photosphere, chromosphere, and corona.

[47]  arXiv:2002.03625 [pdf, other]
Title: Post-Born corrections to the one-point statistics of (CMB) lensing convergence obtained via large deviation theory
Comments: Submitted to MNRAS, 16 pages, comments welcome
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)

Weak lensing of galaxies and CMB photons through the large-scale structure of the Universe is one of the most promising cosmological probes with upcoming experiments dedicated to its measurements such as Euclid/LSST and CMB Stage 4 experiments. With increasingly precise measurements, there is a dire need for accurate theoretical predictions. In this work, we focus on higher order statistics of the weak lensing convergence field, namely its cumulants such as skewness and kurtosis and its one-point probability distribution (PDF), and we quantify using perturbation theory the corrections coming from post-Born effects, meaning beyond the straight-line and independent lenses approximations. At first order, two such corrections arise: lens-lens couplings and geodesic deviation. Though the corrections are small for low source redshifts (below a few percents) and therefore for galaxy lensing, they become important at higher redshifts, notably in the context of CMB lensing, where the non-gaussianities computed from tree-order perturbation theory are found to be of the same order as the signal itself. We include these post-Born corrections on the skewness into a prediction for the one-point convergence PDF obtained with large deviation theory and successfully test these results against numerical simulations. The modelled PDF is indeed shown to perform better than the percent for apertures above ~ 10 arcminutes and typically in the three sigmas region around the mean.

[48]  arXiv:2002.03645 [pdf, other]
Title: Growth of Supermassive Black Hole Seeds in ETG Star-Forming Progenitors: Multiple Merging of Stellar Compact Remnants via Gaseous Dynamical Friction and Gravitational Wave Emission
Comments: 19 pages, 8 Figures. Accepted by ApJ
Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)

We propose a new mechanism for the growth of supermassive black hole (BH) seeds in the star-forming progenitors of local early-type galaxies (ETGs) at $z\gtrsim 1$. This envisages the migration and merging of stellar compact remnants (neutron stars and stellar-mass BHs) via gaseous dynamical friction toward the central high-density regions of such galaxies. We show that, under reasonable assumptions and initial conditions, the process can build up central BH masses of order $10^4-10^6\, M_\odot$ within some $10^7$ yr, so effectively providing heavy seeds before standard disk (Eddington-like) accretion takes over to become the dominant process for further BH growth. Remarkably, such a mechanism may provide an explanation, alternative to super-Eddington accretion rates, for the buildup of billion solar masses BHs in quasar hosts at $z\gtrsim 7$, when the age of the Universe $\lesssim 0.8$ Gyr constitutes a demanding constraint; moreover, in more common ETG progenitors at redshift $z\sim 2-6$ it can concur with disk accretion to build such large BH masses even at moderate Eddington ratios $\lesssim 0.3$ within the short star-formation duration $\lesssim$ Gyr of these systems. Finally, we investigate the perspectives to detect the merger events between the migrating stellar remnants and the accumulating central supermassive BH via gravitational wave emission with future ground and space-based detectors such as the Einstein Telescope (ET) and the Laser Interferometer Space Antenna (LISA).

[49]  arXiv:2002.03654 [pdf, ps, other]
Title: Burst-induced coronal cooling in GS 1826-24 The clock wagging its tail
Journal-ref: A&A 634, A58 (2020)
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

Type I X-ray bursts in GS 1826-24, and in several other systems, may induce cooling of the hot inner accretion flow that surrounds the bursting neutron star. Given that GS 1826-24 remained persistently in the hard state over the period 2003-2008 and presented regular bursting properties, we stacked the spectra of the X-ray bursts detected by INTEGRAL (JEM-X and ISGRI) and XMM-Newton (RGS) during that period to study the effect of the burst photons on the properties of the Comptonizing medium. The extended energy range provided by these instruments allows the simultaneous observation of the burst and persistent emission spectra. We detect an overall change in the shape of the persistent emission spectrum in response to the burst photon shower. For the first time, we observe simultaneously a drop in the hard X-ray emission, together with a soft X-ray excess with respect to the burst blackbody emission. The hard X-ray drop can be explained by burst-induced coronal cooling, while the bulk of the soft X-ray excess can be described by fitting the burst emission with an atmosphere model, instead of a simple blackbody model. Traditionally, the persistent emission was assumed to be invariant during X-ray bursts, and more recently to change only in normalization but not in spectral shape; the observed change in the persistent emission level during X-ray bursts may thus trigger the revision of existing neutron star mass-radius constraints, as the derived values rely on the assumption that the persistent emission does not change during X-ray bursts. The traditional burst fitting technique leads to up to a 10% overestimation of the bolometric burst flux in GS 1826-24, which significantly hampers the comparisons of the KEPLER and MESA model against this 'textbook burster'.

[50]  arXiv:2002.03682 [pdf, other]
Title: High-precision polarimetry of nearby stars (d<50 pc) Mapping the interstellar dust and magnetic field inside the Local Bubble
Comments: 18 pages, 8 figures, 13 tables
Subjects: Astrophysics of Galaxies (astro-ph.GA); Instrumentation and Methods for Astrophysics (astro-ph.IM); Solar and Stellar Astrophysics (astro-ph.SR)

We investigate the linear polarization produced by interstellar dust aligned by the magnetic field in the solar neighborhood (d< 50 pc). We also look for intrinsic effects from circumstellar processes, specifically in terms of polarization variability and wavelength dependence. We aim to detect and map dust clouds which give rise to statistically significant amounts of polarization of the starlight passing through the cloud, and to determine the interstellar magnetic field direction from the position angle of the observed polarization. High-precision broad-band (BVR) polarization observations are made of 361 stars in spectral classes F to G, in the magnitude range 4-9, with detection sensitivity at the level of or better than 10E-5 (0.001 %). Statistically significant (>3 sigma) polarization is found in 115 stars, and > 2 sigma detection in 178 stars, out of the total sample of 361 stars. Polarization maps based on these data show filament-like patterns of polarization position angles which are related to both the heliosphere geometry, the kinematics of nearby clouds, and the Interstellar Boundary EXplorer (IBEX) ribbon magnetic field. From long-term multiple observations, a number (18) of stars show evidence of intrinsic variability at the 10E-5 level. This can be attributed to circumstellar effects (e.g., debris disks and chromospheric activity). The star HD 101805 shows a peculiar wavelength dependence, indicating size distribution of scattering particles different from that of a typical interstellar medium.

[51]  arXiv:2002.03693 [pdf]
Title: The remnant of neutron star-white dwarf merger and the repeating fast radio bursts
Authors: Xiang Liu (Xinjiang Astronomical Observatory, CAS)
Comments: 8 pages, accepted
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

Fast radio bursts (FRBs) at cosmological distances still hold concealed physical origins. Previously Liu (2018) proposes a scenario that the collision between a neutron star (NS) and a white dwarf (WD) can be one of the progenitors of non-repeating FRBs and notices that the repeating FRBs can also be explained if a magnetar formed after such NS-WD merger. In this paper, we investigate this channel of magnetar formation in more detail. We propose that the NS-WD post-merger, after cooling and angular momentum redistribution, may collapse to either a black hole or a new NS or even remains as a hybrid WDNS, depending on the total mass of the NS and WD. In particular, the newly formed NS can be a magnetar if the core of the WD collapsed into the NS while large quantities of degenerate electrons of the WD compressed to the outer layers of the new NS. A strong magnetic field can be formed by the electrons and positive charges with different angular velocities induced by the differential rotation of the newborn magnetar. Such a magnetar can power the repeating FRBs by the magnetic reconnections due to the crustal movements or starquakes.

[52]  arXiv:2002.03739 [pdf, other]
Title: ExoSim: the Exoplanet Observation Simulator
Comments: 23 pages, 14 figures
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)

A new generation of exoplanet research beckons and with it the need for simulation tools that accurately predict signal and noise in transit spectroscopy observations. We developed ExoSim: an end-to-end simulator that models noise and systematics in a dynamical simulation. ExoSim improves on previous simulators in the complexity of its simulation, versatility of use and its ability to be generically applied to different instruments. It performs a dynamical simulation that can capture temporal effects, such as correlated noise and systematics on the light curve. It has also been extensively validated, including against real results from the Hubble WFC3 instrument. We find ExoSim is accurate to within 5% in most comparisons. ExoSim can interact with other models which simulate specific time-dependent processes. A dedicated star spot simulator allows ExoSim to produce simulated observations that include spot and facula contamination. ExoSim has been used extensively in the Phase A and B design studies of the ARIEL mission, and has many potential applications in the field of transit spectroscopy.

[53]  arXiv:2002.03790 [pdf, other]
Title: Complex beam mapping and Fourier optics analysis of a wide field Microwave Kinetic Inductance Detector camera
Comments: This is a post-peer-review, pre-copy edit version of an article published in Journal of Low Temperature Physics. The final authenticated version is available online
Journal-ref: Journal of Low Temperature Physics, 2020
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)

For astronomical instruments, accurate knowledge of the optical pointing and coupling are essential to characterize the alignment and performance of (sub-)systems prior to integration and deployment. Ideally, this requires the phase response of the optical system, which for direct (phase insensitive) detectors was not previously accessible. Here we show development of the phase sensitive complex beam pattern technique using a dual optical source heterodyne technique for a large field of view Microwave Kinetic Inductance Detector camera at 350 GHz. We show here how you can analyze the measured data with Fourier optics, which allows integration into a telescope model to calculate the on sky beam pattern and telescope aperture efficiency prior to deployment at a telescope.

[54]  arXiv:2002.03813 [pdf, other]
Title: A $5^\circ\times5^\circ$ deep HI survey of the M81 group: II. HI distribution and kinematics of IC 2574 and HIJASS J1021+68
Comments: 15 pages, 17 figures. Accepted for publication in MNRAS
Subjects: Astrophysics of Galaxies (astro-ph.GA)

We analyse the eastern region of a $5^\circ\times5^\circ$ deep HI survey of the M81 group containing the dwarf galaxy IC 2574 and the HI complex HIJASS J1021+68, located between the dwarf and the M81 system. The data show that IC 2574 has an extended HI envelope that connects to HIJASS J1021+68 in the form of a collection of small clouds, but no evident connection has been found between IC 2574 and the central members of the M81 group. We argue, based on the morphology of the clouds forming HIJASS J1021+68 and its velocity distribution, that the complex is not a dark galaxy as previously suggested, but is instead a complex of clouds either stripped from, or falling onto the primordial HI envelope of IC 2574. We also use the deep HI observations to map the extended HI envelope around IC 2574 and, using a 3D tilted-ring model, we derive the rotation curve of the galaxy to a larger extent than has been done before. Combining the obtained rotation curve to higher resolution curves from the literature, we constrain the galaxy's dark matter halo parameters.

[55]  arXiv:2002.03818 [pdf, other]
Title: Molecular gas and star formation activity in LIRGs in intermediate redshift clusters
Comments: 26 pages, 10 figures, 5 tables, submitted to A&A on November 26, 2019; still waiting for the referee report
Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)

We investigate the role of dense Mpc-scale environments in processing molecular gas of cluster galaxies as they fall into the cluster cores. We consider $\sim20$ luminous infrared galaxies (LIRGs) in intermediate-$z$ clusters, from the Hershel Lensing Survey and the Local Cluster Substructure Survey. They include MACS J0717.5+3745 at $z=0.546$ and Abell 697, 963, 1763, and 2219 at $z=0.2-0.3$. We have performed far infrared to ultraviolet spectral energy distribution modeling of the LIRGs, which span cluster-centric distances within $r/r_{200}\simeq0.2-1.6$. We have observed the LIRGs in CO(1$\rightarrow$0) or CO(2$\rightarrow$1) with the Plateau de Bure interferometer and its successor NOEMA, as part of five observational programs carried out between 2012 and 2017. We have compared the molecular gas to stellar mass ratio $M(H_2)/M_\star$, star formation rate (SFR), and depletion time ($\tau_{\rm dep}$) of the LIRGs with those of a compilation of cluster and field star forming galaxies. The targeted LIRGs have SFR, $M(H_2)/M_\star$, and $\tau_{\rm dep}$ that are consistent with those of both main sequence (MS) field galaxies and star forming galaxies from the comparison sample. However we find that the depletion time, normalized to the MS value, increases with increasing $r/r_{200}$, with a significance of $2.8\sigma$, which is ultimately due to a deficit of cluster core LIRGs with $\tau_{\rm dep}\gtrsim\tau_{\rm dep,MS}$. We suggest that a rapid exhaustion of the molecular gas reservoirs occurs in the cluster LIRGs and is effective in suppressing their star formation. This mechanism may explain the exponential decrease of the fraction of cluster LIRGs with cosmic time. The compression of the gas in LIRGs, possibly induced by intra-cluster medium shocks, may be responsible for the short depletion timescales, observed in a large fraction of cluster core LIRGs.

[56]  arXiv:2002.03863 [pdf, other]
Title: The Dynamics of Binary Neutron Star Mergers and of GW170817
Comments: 24 pages, 7 figures, 150 of the 150 allowed references used. Invited review for Annual Reviews of Nuclear and Particle Science. Accepted author's version (not copy edited)
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc)

With the first observation of a binary neutron star merger through gravitational waves and light GW170817, compact binary mergers have now taken the center stage in nuclear astrophysics. They are thought to be one of the main astrophysical sites of production of r-process elements, and merger observations have become a fundamental tool to constrain the properties of matter. Here, we review our current understanding of the dynamics of neutron star mergers, in general, and of GW170817 in particular. We discuss the physical processes governing the inspiral, merger, and postmerger evolution, and we highlight the connections between these processes, the dynamics, and the multimessenger observables. Finally, we discuss open questions and issues in the field and the need to address them through a combination of better theoretical models and new observations.

[57]  arXiv:2002.03867 [pdf, other]
Title: The impact of projection effects on cluster observables: stacked lensing and projected clustering
Comments: 23 pages, 20 figures
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)

An optical cluster finder inevitably suffers from projection effects, where it misidentifies a superposition of galaxies in multiple halos along the line-of-sight as a single cluster. Using mock cluster catalogs built from cosmological N-body simulations, we quantify the impact of these projection effects with a particular focus on the observables of interest for cluster cosmology, namely the cluster lensing and the cluster clustering signals. We find that "observed" clusters, i.e. clusters identified by our cluster finder algorithm, exhibit lensing and clustering signals that deviate from expectations based on a statistically isotropic halo model -- while both signals agree with halo model expectations on small scales, they show unexpected boosts on large scales, by up to a factor of 1.2 or 1.4 respectively. We identify the origin of these boosts as the inherent selection bias of optical cluster finders for clusters embedded within filaments aligned with the line-of-sight, and show that a minority ($\sim 30\%$) of such clusters within the entire sample is responsible for this observed boost. We discuss the implications of our results on previous studies of optical cluster, as well as prospects for identifying and mitigating projection effects in future cluster cosmology analyses.

[58]  arXiv:2002.03870 [pdf]
Title: A Two Year Survey for VLF Emission from Fireballs
Comments: 51 pages; accepted for publication in Planetary and Space Science
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM)

Here we report on a two year continuous survey to examine possible VLF signals associated with meteors brighter than magnitude -5. Our survey allowed both calibrated temporal and spatial correlations between VLF signals and fireball lightcurves. We used continuous observations from the Atmospheric Weather Electromagnetic System for Observation Modeling and Education (AWESOME) VLF receiver system (Cohen et al., 2010) deployed at the Elginfield Observatory near London, Ontario, Canada (43N, 81W) to monitor VLF radio signals and correlate with all-sky video recordings of fireballs. This survey from May 2017 to March 2019 was cued using fireballs detected by the Southern Ontario Meteor Network (Brown et al., 2010; Weryk et al., 2007). The GPS conditioned timing of the AWESOME system was continuously synchronized with video recordings directly in the video stream to ensure sub-frame VLF-optical time calibration. The AWESOME system has two orthogonal VLF antennas which permits directional calculation of incoming VLF signals, which were compared to the apparent optically measured locations of simultaneously detected fireballs. VLF events potentially linked to fireballs were checked against the National Lightning Detection Network (NLDN) database to remove false positive association with lightning. During the two year survey interval, over 80 bright meteors (apparent magnitude brighter than -5, brightest recorded event -7.8) were detected and compared to VLF signals detected by the AWESOME system. No definitive evidence was found for VLF emission from meteors up to a limiting magnitude of -7.8.

[59]  arXiv:2002.03881 [pdf, other]
Title: A new method for measuring the meteor mass index: application to the 2018 Draconid meteor shower outburst
Comments: Accepted for publication in A&A
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM)

Context. Several authors predicted an outburst of the Draconid meteor shower in 2018, but with an uncertain level of activity. Aims. Optical meteor observations were used to derive the population and mass indices, flux, and radiant positions of Draconid meteors. Methods. 90 minutes of multi-station observations after the predicted peak of activity were performed using highly sensitive Electron Multiplying Charge Coupled Device (EMCCD) cameras. The data calibration is discussed in detail. A novel maximum likelihood estimation method of computing the population and mass index with robust error estimation was developed. We apply the method to observed Draconids and use the values to derive the flux. Meteor trajectories are computed and compared to predicted radiant positions from meteoroid ejection models. Results. We found that the mass index was $1.74 \pm 0.18$ in the 30 minute bin after the predicted peak, and $2.32 \pm 0.27$ in the next 60 minutes. The location and the dispersion of the radiant matches well to modeled values, but there is an offset of $0.4^{\circ}$ in solar longitude.

[60]  arXiv:2002.03890 [pdf, other]
Title: Discrete Chi-square Method for Detecting Many Signals
Authors: Lauri Jetsu
Comments: 18 pages, 12 figures, 8 tables
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Methodology (stat.ME)

Unambiguous detection of signals superimposed on unknown trends is difficult for unevenly spaced data. Here, we formulate the Discrete Chi-square Method (DCM) that can determine the best model for many signals superimposed on arbitrary polynomial trends. DCM minimizes the Chi-square for the data in the multi-dimensional tested frequency space. The required number of tested frequency combinations remains manageable, because the method test statistic is symmetric in this tested frequency space. With our known tested constant frequency grid values, the non-linear DCM model becomes linear, and all results become unambiguous. We test DCM with simulated data containing different mixtures of signals and trends. DCM gives unambiguous results, if the signal frequencies are not too close to each other, and none of the signals is too weak. It relies on brute computational force, because all possible free parameter combinations for all reasonable linear models are tested. DCM works like winning a lottery by buying all lottery tickets. Anyone can reproduce all our results with the DCM computer code.

[61]  arXiv:2002.03897 [pdf, ps, other]
Title: Perturbation level interacting dark energy model and its consequence on late-time cosmological parameters
Comments: 11 pages, 8 figures
Journal-ref: Phys. Rev. D 101, 043503 (2020)
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)

In the present paper, we study the capability of interacting dark energy model with pure momentum transfer in the dark sector to reconcile tensions between low redshift observations and cosmic microwave background (CMB) results. This class of interacting model with pure momentum exchange introduces modifications to the standard model in the level of perturbation. We investigate the model by comparing to observational data, including integrated Sachs-Wolfe-galaxy cross-correlation, galaxy power spectrum, $f \sigma_8$, and CMB data. It is shown that this model can alleviate the observed tension between local and global measurements of $\sigma_8$. According to our results, the best fit value of $\sigma_8$ for interacting model is $0.700$, which is lower than the one for $\Lambda$CDM model and also is consistent with low redshift observations. Furthermore, we perform a forecast analysis to find the constraints on parameters of the interacting model from future experiments.

[62]  arXiv:2002.03901 [pdf, other]
Title: Radio eclipses of exoplanets by the winds of their host stars
Comments: 7 pages, 7 figures. Accepted for publication in MNRAS
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP)

The search for exoplanetary radio emission has resulted in zero conclusive detections to date. Various explanations for this have been proposed, from the observed frequency range, telescope sensitivity, to beaming of the emission. In a recent paper, we illustrated that exoplanets can orbit through the radio photosphere of the wind of the host star, a region that is optically thick at a specific frequency, for a large fraction of their orbits. As a result, radio emission originating from the planet could be absorbed or `eclipsed' by the wind of the host star. Here we investigate how the properties of the stellar wind and orbital parameters affect the fraction of the orbit where the planet is eclipsed by the stellar wind. We show that planets orbiting stars with low density winds are more favourable for detection in the radio. In terms of the orbital parameters, emission from transiting planets can escape the stellar wind easiest. We apply our model to the $\tau$~Boo planetary system, and show that observing the fraction of the planet's orbit where it is eclipsed by the wind of the host star could be used to constrain the properties of the stellar wind. However, our model developed would need to be used in conjunction with a separate method to disentangle the mass-loss rate and temperature of the stellar wind.

[63]  arXiv:2002.03931 [pdf, ps, other]
Title: SALT revisits DY Cen: a rapidly-evolving strontium-rich single helium star
Comments: MNRAS accepted 2020 February. 11 pages, 6 figures, + 4 page appendix incl. 4 figures
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)

The hydrogen-deficient star DY Cen has been reported as an R CrB-type variable, an extreme helium star (with some hydrogen), and as a single-lined spectroscopic binary. It has been associated with a dramatic change in visual brightness and colour corresponding to a change in effective temperature ($T_{\mathrm eff}$) of some 20,000 K in the last century. To characterize the binary orbit and $T_{\mathrm eff}$ changes more precisely, new high-resolution spectroscopy has been obtained with SALT. The previous orbital period is not confirmed; previous measurements may have been confused by the presence of pulsations. Including data from earlier epochs (1987, 2002, and 2010), self-consistent spectral analyses from all four epochs demonstrate an increase in $T_{\mathrm eff}$ from 18,800 to 24,400 K between 1987 and 2015. Line profiles demonstrate that the surface rotation has increased by a factor two over the same interval. This is commensurate with the change in $T_{\mathrm eff}$ and an overall contraction. Rotation will exceed critical if contraction continues. The 1987 spectrum shows evidence of a very high abundance of the s-process element strontium. The very rapid evolution, non-negligible surface hydrogen and high surface strontium point to a history involving a very late thermal pulse. Observations over the next thirty years should look for a decreasing pulsation period, reactivation of R CrB-type activity as the star seeks to shed angular momentum and increasing illumination by emission lines from nebular material ejected in the past.

[64]  arXiv:2002.03946 [pdf, other]
Title: A fundamental test for MOND
Comments: 12 pages, 4 figures
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA); General Relativity and Quantum Cosmology (gr-qc)

The Radial Acceleration Relation (RAR) shows a strong correlation between two accelerations associated to galaxy rotation curves. The relation between these accelerations is given by a nonlinear function which depends on an acceleration scale $a_\dagger$. Some have interpreted this as an evidence for a gravity model, such as Modified Newtonian Dynamics (MOND), which posits a fundamental acceleration scale $a_0$ common to all the galaxies. However, it was later shown, using Bayesian inference, that this seems not to be the case: the $a_0$ credible intervals for individual galaxies were not found to be compatible among themselves. This type of test is a fundamental test for MOND as a theory for gravity, since it directly evaluates its basic assumption and this using the data that most favor MOND: galaxy rotation curves. Here we improve upon the previous analyses by introducing a more robust method to assess the compatibility between the credible intervals, in particular without Gaussian approximations. We directly estimate, using a Monte Carlo simulation, that the existence of a fundamental acceleration is incompatible with the data at more than $5\sigma$. We also consider quality cuts in order to show that our results are robust against outliers. In conclusion, the new analysis further supports the claim that the acceleration scale found in the RAR is an emergent quantity.

[65]  arXiv:2002.03958 [pdf, other]
Title: HD 191939: Three Sub-Neptunes Transiting a Sun-like Star Only 54 pc Away
Comments: 23 pages, 9 figures, 5 tables
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)

We present the discovery of three sub-Neptune-sized planets transiting the nearby and bright Sun-like star HD 191939 (TIC 269701147, TOI 1339), a $K_{s}=7.18$ magnitude G8V dwarf at a distance of only 54 parsecs. This multi-planetary system is one of the best candidates for atmospheric characterization to date, with all its known planets suitable for multi-wavelength transmission spectroscopy. We validate the planetary nature of the transit signals by combining five months of data from the Transiting Exoplanet Survey Satellite with follow-up ground-based photometry, archival optical images, radial velocities, and high angular resolution observations. The three sub-Neptunes have similar radii ($R_{b} = 3.37^{+0.13}_{-0.13}\,R_{\oplus}$, $R_{c}=3.22_{-0.14}^{+0.15}\,R_{\oplus}$, and $R_{d}=3.16_{-0.11}^{+0.11}\,R_{\oplus}$) and their orbits are consistent with a stable, circular, and co-planar architecture near mean motion resonances of 1:3 and 3:4 ($P_{b}=8.88$ days, $P_{c}=28.58$ days, and $P_{d}=38.35$ days). The HD 191939 system is an excellent candidate for precise mass determinations of the planets with high-resolution spectroscopy due to the host star's brightness and low chromospheric activity. Moreover, the system's compact and near-resonant nature can provide an independent way to measure planetary masses via transit timing variations while also enabling dynamical and evolutionary studies. Finally, as a prime target for transmission spectroscopy of all three planets' atmospheres, HD 191939 can offer a unique insight into multiple sub-Neptunes born from a proto-planetary disk that may have resembled that of the early Sun.

[66]  arXiv:2002.03998 [pdf, other]
Title: Space, time and velocity association of successive coronal mass ejections
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Space Physics (physics.space-ph)

Our aim is to investigate the possible physical association between consecutive coronal mass ejections (CMEs). Through a statistical study of the main characteristics of 27761 CMEs observed by SOHO/LASCO during the past 20 years. We found the waiting time (WT) or time elapsed between two consecutive CMEs is $< 5$ hrs for 59\% and $< 25$ hrs for 97\% of the events, and the CME WTs follow a Pareto Type IV statistical distribution. The difference of the position-angle of a considerable population of consecutive CME pairs is less than $30^\circ$, indicating the possibility that their source locations are in the same region. The difference between the speed of trailing and leading consecutive CMEs follows a generalized Student t-distribution. The fact that the WT and the speed difference have heavy-tailed distributions along with a detrended fluctuation analysis shows that the CME process has a long-range dependence. As a consequence of the long-range dependence, we found a small but significative difference between the speed of consecutive CMEs, with the speed of the trailing CME being higher than the speed of the leading CME. The difference is largest for WTs < 2 hrs and tends to be zero for WTs > 10 hrs, and it is more evident during the ascending and descending phases of the solar cycle. We suggest that this difference may be caused by a drag force acting over CMEs closely related in space and time.

[67]  arXiv:2002.04003 [pdf, other]
Title: A strongly changing accretion morphology during the outburst decay of the neutron star X-ray binary 4U 1608-52
Comments: Accepted for publication in MNRAS
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

It is commonly assumed that the properties and geometry of the accretion flow in transient low-mass X-ray binaries (LMXBs) significantly change when the X-ray luminosity decays below $\sim 10^{-2}$ of the Eddington limit ($L_{\rm Edd}$). However, there are few observational cases where the evolution of the accretion flow is tracked in a single X-ray binary over a wide dynamic range. In this work, we use NuSTAR and NICER observations obtained during the 2018 accretion outburst of the neutron star LMXB 4U 1608-52, to study changes in the reflection spectrum. We find that the broad Fe-K$\alpha$ line and Compton hump, clearly seen during the peak of the outburst when the X-ray luminosity is $\sim 10^{37}$ erg/s ($\sim 0.05$ $L_{\rm Edd}$), disappear during the decay of the outburst when the source luminosity drops to $\sim 4.5 \times 10^{35}$ erg/s ($\sim 0.002$ $L_{\rm Edd}$). We show that this non-detection of the reflection features cannot be explained by the lower signal-to-noise at lower flux, but is instead caused by physical changes in the accretion flow. Simulating synthetic NuSTAR observations on a grid of inner disk radius, disk ionisation, and reflection fraction, we find that the disappearance of the reflection features can be explained by either increased disk ionisation ($\log \xi \geq 4.1$) or a much decreased reflection fraction. A changing disk truncation alone, however, cannot account for the lack of reprocessed Fe-K$\alpha$ emission. The required increase in ionisation parameter could occur if the inner accretion flow evaporates from a thin disk into a geometrically thicker flow, such as the commonly assumed formation of an radiatively inefficient accretion flow at lower mass accretion rates.

[68]  arXiv:2002.04024 [pdf, other]
Title: Weak-lensing observables in relativistic N-body simulations
Comments: 20 pages, 17 figures. To be submitted to MNRAS, comments are welcome
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc)

We investigate for the first time weak lensing in a high-resolution relativistic N-body simulation, which includes all relevant effects from general relativity. We integrate the photon geodesics backwards from the observer to the emitters. Our analysis is fully relativistic and non-perturbative for the scalar part of the gravitational potential and first-order in the vector part, frame dragging. We solve the Sachs optical equations and study in detail the weak-lensing convergence, ellipticity and rotation. We present the angular power spectra and one-point probability distribution functions for the weak-lensing variables, which we find are broadly in agreement with comparable Newtonian simulations. Our geometric approach, however, is more robust and flexible, and can therefore be applied consistently to non-standard cosmologies and modified theories of gravity.

[69]  arXiv:2002.04029 [pdf, other]
Title: Gargantuan chaotic gravitational three-body systems and their irreversibility to the Planck length
Comments: Accepted for publication in MNRAS. 7 pages, 4 figures
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR); Chaotic Dynamics (nlin.CD); Computational Physics (physics.comp-ph)

Chaos is present in most stellar dynamical systems and manifests itself through the exponential growth of small perturbations. Exponential divergence drives time irreversibility and increases the entropy in the system. A numerical consequence is that integrations of the N-body problem unavoidably magnify truncation and rounding errors to macroscopic scales. Hitherto, a quantitative relation between chaos in stellar dynamical systems and the level of irreversibility remained undetermined. In this work we study chaotic three-body systems in free fall initially using the accurate and precise N-body code Brutus, which goes beyond standard double-precision arithmetic. We demonstrate that the fraction of irreversible solutions decreases as a power law with numerical accuracy. This can be derived from the distribution of amplification factors of small initial perturbations. Applying this result to systems consisting of three massive black holes with zero total angular momentum, we conclude that up to five percent of such triples would require an accuracy of smaller than the Planck length in order to produce a time-reversible solution, thus rendering them fundamentally unpredictable.

[70]  arXiv:2002.04031 [pdf, other]
Title: NGC 7469 as seen by MEGARA: new results from high-resolution IFU spectroscopy
Comments: 20 pages, 12 figures, 3 Tables; accepted for publication in Monthly Notices of the Royal Astronomical Society
Subjects: Astrophysics of Galaxies (astro-ph.GA)

We present our analysis of high-resolution (R $\sim$ 20 000) GTC/MEGARA integral-field unit spectroscopic observations, obtained during the commissioning run, in the inner region (12.5 arcsec x 11.3 arcsec) of the active galaxy NGC7469, at spatial scales of 0.62 arcsec. We explore the kinematics, dynamics, ionisation mechanisms and oxygen abundances of the ionised gas, by modelling the H$\alpha$-[NII] emission lines at high signal-to-noise (>15) with multiple Gaussian components. MEGARA observations reveal, for the first time for NGC7469, the presence of a very thin (20 pc) ionised gas disc supported by rotation (V/$\sigma$ = 4.3), embedded in a thicker (222 pc), dynamically hotter (V/$\sigma$ = 1.3) one. These discs nearly co-rotate with similar peak-to-peak velocities (163 vs. 137 km/s ), but with different average velocity dispersion (38 vs. 108 km/s ). The kinematics of both discs could be possibly perturbed by star-forming regions. We interpret the morphology and the kinematics of a third (broader) component ($\sigma$ > 250 km/s) as suggestive of the presence of non-rotational turbulent motions possibly associated either to an outflow or to the lense. For the narrow component, the [NII]/H$\alpha$ ratios point to the star-formation as the dominant mechanism of ionisation, being consistent with ionisation from shocks in the case of the intermediate component. All components have roughly solar metallicity. In the nuclear region of NGC7469, at r < 1.85 arcsec, a very broad (FWHM = 2590 km/s ) H{\alpha} component is contributing (41%) to the global H$\alpha$ -[NII]profile, being originated in the (unresolved) broad line region of the Seyfert 1.5 nucleus of NGC7469.

Cross-lists for Tue, 11 Feb 20

[71]  arXiv:2002.03022 (cross-list from hep-ph) [pdf, other]
Title: Galactic Condensates composed of Multiple Axion Species
Comments: 29 pages, 8 figures
Subjects: High Energy Physics - Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Theory (hep-th)

Ultralight scalar dark matter has been proposed to constitute a component of dark matter, though the minimal scenarios have increasingly become constrained. In this work, we analyze scenarios where the dark matter consists of more than one ultralight boson, each with different masses. This potentially leads to formation of gravitationally-bound Bose-Einstein condensates with structures that are very different from condensates composed of a single scalar field. By generalizing from the well-understood single-flavor case, we explore a large range of input parameters, subject to stability criteria, and determine the allowed parameter space for two-flavor condensates as a function of particle physics parameters, paying particular attention to cases where such condensates could compose galactic cores. We also analyze single-flavor condensates subject to external gravity from massive inner bodies and find that such systems may mimic the size of galactic cores as well.

[72]  arXiv:2002.03025 (cross-list from gr-qc) [pdf, other]
Title: A Neutron Star with a Strange Quark Star-like Mass-Radius Relation
Comments: 8 pages, 2 figures
Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO)

We study the structure of spherically symmetric and static objects in the presence of a nonminimally coupled scalar field having a potential of the form $V(\phi)=-\mu^2\phi^2/2+\lambda\phi^4/4$. We numerically solve equations of the system using two different realistic equations of state for neutron matter and give the mass-radius relations as well as the radial profiles of the scalar field, densities and the mass function for a sample configuration. We show that a specific solution type encountered in such systems causes characteristic neutron star mass-radius relations to turn into the ones belonging to strange quark stars.

[73]  arXiv:2002.03185 (cross-list from physics.hist-ph) [pdf, ps, other]
Title: Stephen William Hawking: A Biographical Memoir
Comments: 38 pages
Journal-ref: Biogr. Mems Fell. R. Soc. 66, 267 (2019)
Subjects: History and Philosophy of Physics (physics.hist-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)

Stephen Hawking's contributions to the understanding of gravity, black holes and cosmology were truly immense. They began with the singularity theorems in the 1960s followed by his discovery that black holes have an entropy and consequently a finite temperature. Black holes were predicted to emit thermal radiation, what is now called Hawking radiation. He pioneered the study of primordial black holes and their potential role in cosmology. His organisation of and contributions to the Nuffield Workshop in 1982 consolidated the picture that the large-scale structure of the universe originated as quantum fluctuations during the inflationary era. Work on the interplay between quantum mechanics and general relativity resulted in his formulation of the concept of the wavefunction of the universe. The tension between quantum mechanics and general relativity led to his struggles with the information paradox concerning deep connections between these fundamental areas of physics.
These achievements were all accomplished following the diagnosis during the early years of Stephen's studies as a post-graduate student in Cambridge that he had incurable motor neuron disease -- he was given two years to live. Against all the odds, he lived a further 55 years. The distinction of his work led to many honours and he became a major public figure, promoting with passion the needs of disabled people. His popular best-selling book A Brief History of Time made cosmology and his own work known to the general public worldwide. He became an icon for science and an inspiration to all.

[74]  arXiv:2002.03186 (cross-list from gr-qc) [pdf, ps, other]
Title: Distinguishing Brans-Dicke-Kerr type naked singularities and black holes with their thin disk electromagnetic radiation properties
Comments: 20 pages, 6 figures, accepted for publication in EPJC
Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Theory (hep-th)

The possible existence of naked singularities, hypothetical astrophysical objects, characterized by a gravitational singularity without an event horizon is still an open problem in present day astrophysics. From an observational point of view distinguishing between astrophysical black holes and naked singularities also represents a major challenge. One possible way of differentiating naked singularities from black holes is through the comparative study of thin accretion disks properties around these different types of compact objects. In the present paper we continue the comparative investigation of accretion disk properties around axially-symmetric rotating geometries in Brans-Dicke theory in the presence of a massless scalar field. The solution of the field equations contains the Kerr metric as a particular case, and, depending on the numerical values of the model parameter $\gamma$, has also solutions corresponding to non-trivial black holes and naked singularities, respectively. Due to the differences in the exterior geometries between black holes and Brans-Dicke-Kerr naked singularities, the thermodynamic and electromagnetic properties of the disks (energy flux, temperature distribution and equilibrium radiation spectrum) are different for these two classes of compact objects, consequently giving clear observational signatures that could discriminate between black holes and naked singularities.

[75]  arXiv:2002.03285 (cross-list from gr-qc) [pdf, other]
Title: Pulsar timing array signals induced by black hole binaries in relativistic eccentric orbits
Subjects: General Relativity and Quantum Cosmology (gr-qc); Astrophysics of Galaxies (astro-ph.GA)

Individual supermassive black hole binaries in non-circular orbits are possible nanohertz gravitational wave sources for the rapidly maturing Pulsar Timing Array experiments. We develop an accurate and efficient approach to compute Pulsar Timing Array signals due to gravitational waves from inspiraling supermassive black hole binaries in relativistic eccentric orbits. Our approach employs a Keplerian-type parametric solution to model third post-Newtonian accurate precessing eccentric orbits while a novel semi-analytic prescription is provided to model the effects of quadrupolar order gravitational wave emission. These inputs lead to a semi-analytic prescription to model such signals, induced by non-spinning black hole binaries inspiralling along arbitrary eccentricity orbits. Additionally, we provide a fully analytic prescription to model Pulsar Timing Array signals from black hole binaries inspiraling along moderately eccentric orbits, influenced by Boetzelet al.[Phys. Rev. D 96,044011(2017)]. These approaches are being incorporated into Enterprise and TEMPO2 for searching the presence of such binaries in Pulsar Timing Array datasets.

[76]  arXiv:2002.03371 (cross-list from math.NA) [pdf, other]
Title: Provably Physical-Constraint-Preserving Discontinuous Galerkin Methods for Multidimensional Relativistic MHD Equations
Subjects: Numerical Analysis (math.NA); Instrumentation and Methods for Astrophysics (astro-ph.IM); Computational Physics (physics.comp-ph); Fluid Dynamics (physics.flu-dyn); Plasma Physics (physics.plasm-ph)

We propose and analyze a class of robust, uniformly high-order accurate discontinuous Galerkin (DG) schemes for multidimensional relativistic magnetohydrodynamics (RMHD) on general meshes. A distinct feature of the schemes is their physical-constraint-preserving (PCP) property, i.e., they are proven to preserve the subluminal constraint on the fluid velocity and the positivity of density, pressure, and specific internal energy. Developing PCP high-order schemes for RMHD is highly desirable but remains a challenging task, especially in the multidimensional cases, due to the inherent strong nonlinearity in the constraints and the effect of the magnetic divergence-free condition. Inspired by some crucial observations at the PDE level, we construct the provably PCP schemes by using the locally divergence-free DG schemes of the recently proposed symmetrizable RMHD equations as the base schemes, a limiting technique to enforce the PCP property of the DG solutions, and the strong-stability-preserving methods for time discretization. We rigorously prove the PCP property by using a novel "quasi-linearization" approach to handle the highly nonlinear physical constraints, technical splitting to offset the influence of divergence error, and sophisticated estimates to analyze the beneficial effect of the additional source term in the symmetrizable RMHD system. Several two-dimensional numerical examples are provided to confirm the PCP property and to demonstrate the accuracy, effectiveness and robustness of the proposed PCP schemes.

[77]  arXiv:2002.03402 (cross-list from gr-qc) [pdf, other]
Title: Feynman Rules for Stochastic Inflationary Correlators
Comments: 30 pages
Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Theory (hep-th)

We elaborate on the functional integral describing the stochastic dynamics of a spectator field during inflation, comparing its diagrammatic expansion to that obtained directly from a perturbative solution of the corresponding Langevin equation. We state Feynman rules for computing arbitrary temporal $n$-point functions and perform some illustrative computations for a $\lambda\phi^4$ interaction, paying attention to the role played by a functional Jacobian determinant in the path integral. We also briefly consider the case when the field contributes to the expansion rate, making the noise multiplicative, which introduces additional vertices.

[78]  arXiv:2002.03450 (cross-list from gr-qc) [pdf, ps, other]
Title: Black holes in the Einstein-aether theory: Quasinormal modes and time-domain evolution
Authors: M.S. Churilova
Comments: 8 pages, 4 figures, revtex
Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Theory (hep-th)

We propose accurate calculations of quasinormal modes of black holes in the Einstein-aether theory, which were previously considered in the literature, partially, with insufficient accuracy. We also show that the arbitrarily long lived modes, quasi-resonances, are allowed in the Einstein-aether theory as well and demonstrate that the asymptotic tails, unlike quasinormal frequencies, are indistinguishable from those in the Einstein theory.

[79]  arXiv:2002.03525 (cross-list from physics.ins-det) [pdf, other]
Title: Crystal Defects: A Portal To Dark Matter Detection
Subjects: Instrumentation and Detectors (physics.ins-det); Cosmology and Nongalactic Astrophysics (astro-ph.CO); Materials Science (cond-mat.mtrl-sci); High Energy Physics - Experiment (hep-ex)

We propose to use the defect creation energy loss in commonly used high energy physics solid state detectors as a tool to statistically identify dark matter signal from background. We simulate the energy loss in the process of defect creation using density functional theory and molecular dynamics methods and calculate the corresponding expected dark matter spectra. We show that in phonon-mediated solid state detectors, the energy loss due to defect creation convolved with the expected dark matter interaction signal results in a significant change in the expected spectra for common detector materials. With recent progress towards $\sim$10 eV threshold low-mass dark matter searches, this variation in expected dark matter spectrum can be used as a direct signature of dark matter interactions with atomic nuclei.

[80]  arXiv:2002.03603 (cross-list from gr-qc) [pdf, ps, other]
Title: The LISA-Taiji network
Comments: 6 pages. 2 figures
Journal-ref: Nature Astronomy 4 (2020) 108-109
Subjects: General Relativity and Quantum Cosmology (gr-qc); Instrumentation and Methods for Astrophysics (astro-ph.IM)

Both LISA and Taiji, planned space-based gravitational-wave detectors in orbit around the Sun, are expected to launch in 2030-2035. Assuming a one-year overlap, we explore a potential LISA-Taiji network to fast and accurately localize the gravitational-wave sources.

[81]  arXiv:2002.03934 (cross-list from nucl-ex) [pdf, other]
Title: Study of the $^{25}$Mg(d,p)$^{26}$Mg reaction to constrain the $^{25}$Al(p,$γ$)$^{26}$Si resonant reaction rates in nova burning conditions
Comments: Final version accepted and published. 6 pages and 3 figures
Journal-ref: Eur. Phys. J. A (2020) 56:36
Subjects: Nuclear Experiment (nucl-ex); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Theory (nucl-th)

The rate of the $^{25}$Al($p$,$\gamma$)$^{26}$Si reaction is one of the few key remaining nuclear uncertainties required for predicting the production of the cosmic $\gamma$-ray emitter $^{26}$Al in explosive burning in novae. This reaction rate is dominated by three key resonances ($J^{\pi}=0^{+}$, $1^{+}$ and $3^{+}$) in $^{26}$Si. Only the $3^{+}$ resonance strength has been directly constrained by experiment. A high resolution measurement of the $^{25}$Mg($d$,$p$) reaction was used to determine spectroscopic factors for analog states in the mirror nucleus, $^{26}$Mg. A first spectroscopic factor value is reported for the $0^{+}$ state at 6.256 MeV, and a strict upper limit is set on the value for the $1^{+}$ state at 5.691 MeV, that is incompatible with an earlier ($^{4}$He,$^{3}$He) study. These results are used to estimate proton partial widths, and resonance strengths of analog states in $^{26}$Si contributing to the $^{25}$Al($p$,$\gamma$)$^{26}$Si reaction rate in nova burning conditions.

Replacements for Tue, 11 Feb 20

[82]  arXiv:1401.1535 (replaced) [pdf, ps, other]
Title: An Updated Version of the Unified Radio Catalog: A Multi-Wavelength Radio and Optical Catalog of Quasars and Radio Galaxies
Comments: 3 pages, 4 figures. An abbreviated version of this submission appeared in Conference Proceedings for IAU Symposium 304 "Multi-wavelength AGN Surveys and Studies". 7 Feb 2020: updated URL for data access
Journal-ref: 2014IAUS..304..238K
Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
[83]  arXiv:1709.03798 (replaced) [pdf, other]
Title: New class of naked singularities and their observational signatures
Comments: Substantial modifications in the results. Present version is fully re-written, and the title is also changed. 24 pages, 10 figures
Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Theory (hep-th)
[84]  arXiv:1709.06535 (replaced) [pdf, other]
Title: Observational Signatures of Gamma Rays from Bright Blazars and Wakefield Theory
Authors: N. E. Canac, K. N. Abazajian, T. Tajima (UC Irvine), T. Ebisuzaki (RIKEN), S. Horiuchi (Virginia Tech)
Comments: 10 pages, 6 figures. matches version to be published in MNRAS
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
[85]  arXiv:1805.01968 (replaced) [pdf, other]
Title: Comparison of physical and observational galaxy cluster modelling
Comments: 12 pages, 6 figures, 9 tables, 12 equations, MNRAS
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
[86]  arXiv:1805.01991 (replaced) [pdf, ps, other]
Title: Physical modelling of galaxy clusters detected by Planck
Comments: 16 pages, 15 figures, 5 tables, 18 equations, MNRAS
Journal-ref: Monthly Notices of the Royal Astronomical Society, Volume 483, Issue 3, March 2019, Pages 3529 to 3544
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
[87]  arXiv:1807.08153 (replaced) [pdf, ps, other]
Title: Dynamical Evidence of a Solitonic Core of $10^{9}M_\odot$ in the Milky Way
Comments: 5 pages, 2 figures, minor typos fixed. Accepted for publication on Physics of Dark Universe
Subjects: Astrophysics of Galaxies (astro-ph.GA); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)
[88]  arXiv:1809.03325 (replaced) [pdf, other]
Title: Physical modelling of galaxy clusters using Einasto dark matter profiles
Comments: 14 pages, 9 figures, 3 tables, 28 equations, MNRAS 2019
Journal-ref: MNRAS 489 (2019), 3135-3148
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
[89]  arXiv:1811.05583 (replaced) [pdf, other]
Title: A Stable Finite-Volume Method for Scalar-Field Dark Matter
Authors: Philip F. Hopkins (Caltech)
Comments: 9 pages, 3 figures. Updated to published (MNRAS) version. Expanded from first draft to present a family of related numerical schemes, with additional discussion of nodes
Journal-ref: MNRAS, 2019, 489, 2367
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
[90]  arXiv:1811.12462 (replaced) [pdf, other]
Title: Radiative Stellar Feedback in Galaxy Formation: Methods and Physics
Authors: Philip F. Hopkins (Caltech), Michael Y. Grudic (Caltech), Andrew R. Wetzel (UC Davis), Dusan Keres (UCSD), Claude-Andre Gaucher-Giguere (Northwestern), Xiangcheng Ma (UC Berkeley), Norman Murray (CITA), Nathan Butcher (UCSD)
Comments: 28 pages, 14 figures. Updated to match published MNRAS version
Journal-ref: MNRAS, 2020, 491, 3702
Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO); Instrumentation and Methods for Astrophysics (astro-ph.IM)
[91]  arXiv:1901.09980 (replaced) [pdf, other]
Title: Sunyaev--Zel'dovich profile fitting with joint AMI-Planck analysis
Comments: 13 pages, 10 figures. Submitted to MNRAS. Post-referee version
Journal-ref: MNRAS 486 (2019) 2116-2128
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
[92]  arXiv:1904.09913 (replaced) [pdf, ps, other]
Title: The Scalar Hexaquark $uuddss$: a Candidate to Dark Matter?
Comments: 8 Pages and 2 Figures
Subjects: High Energy Physics - Phenomenology (hep-ph); Astrophysics of Galaxies (astro-ph.GA); High Energy Physics - Experiment (hep-ex); High Energy Physics - Lattice (hep-lat)
[93]  arXiv:1905.04321 (replaced) [pdf, other]
Title: But What About... Cosmic Rays, Magnetic Fields, Conduction, & Viscosity in Galaxy Formation
Authors: Philip F. Hopkins (Caltech), T. K. Chan (UCSD), Shea Garrison-Kimmel (Caltech), Suoqing Ji (Caltech), Kung-Yi Su (Caltech), Cameron B. Hummels (Caltech), Dusan Keres (UCSD), Eliot Quataert (Berkeley), Claude-Andre Faucher-Giguere (Northwestern)
Comments: 35 pages, 23 figures. Updated to match published (MNRAS) version
Journal-ref: MNRAS, 2020, 492, 3465
Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Astrophysical Phenomena (astro-ph.HE)
[94]  arXiv:1905.09110 (replaced) [pdf, other]
Title: Nested sampling on non-trivial geometries
Authors: Kamran Javid
Comments: 13 pages, 11 figures, 28 equations
Subjects: Computation (stat.CO); Instrumentation and Methods for Astrophysics (astro-ph.IM); Data Analysis, Statistics and Probability (physics.data-an)
[95]  arXiv:1906.09475 (replaced) [pdf, other]
Title: Neutrino spin-flavor oscillations in solar environment
Comments: 18 pages, 6 figures, 1 table
Subjects: High Energy Physics - Phenomenology (hep-ph); Solar and Stellar Astrophysics (astro-ph.SR)
[96]  arXiv:1907.00966 (replaced) [pdf, other]
Title: Shock acceleration efficiency in radio relics
Comments: Matched to the A&A published version, minor grammar and typo fixes
Journal-ref: 2020, A&A, 634, A64
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
[97]  arXiv:1907.01394 (replaced) [pdf, ps, other]
Title: Gyroscope precession frequency analysis of a five dimensional charged rotating Kaluza-Klein black hole
Authors: Mustapha Azreg-Aïnou, Mubasher Jamil (Corresponding Author), Kai Lin
Comments: 14 pages, 4 figures, to be published in Chinese Physics C
Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE)
[98]  arXiv:1907.10403 (replaced) [pdf, other]
Title: Revisiting non-Gaussianity in multifield inflation with curved field space
Comments: 23 pages + appendices. Minor modifications. Matches version published in JHEP
Subjects: High Energy Physics - Theory (hep-th); Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc)
[99]  arXiv:1909.05346 (replaced) [pdf, ps, other]
Title: Theoretical Cosmology
Comments: Some references updated. Published as Topical Review in CQG
Journal-ref: Class. Quant. Grav. v37 013001 (2020)
Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
[100]  arXiv:1909.07408 (replaced) [pdf, other]
Title: Galaxy cluster hydrostatic masses using Tolman-Oppenheimer-Volkoff equation
Comments: 5 pages, 1 figure. Accepted for publication in Physics of the Dark Universe
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
[101]  arXiv:1909.08847 (replaced) [pdf, other]
Title: The mass-radius relation for neutron stars in $f(R)=R+αR^2$ gravity: a comparison between purely metric and torsion formulations
Comments: 16 pages, accepted for publication in Phys. Rev. D
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)
[102]  arXiv:1909.09385 (replaced) [pdf, other]
Title: Silhouette of M87*: A new window to peek into the world of hidden dimensions
Comments: v3, Published as Rapid Communication in PRD, 16 pages, 6 figures
Journal-ref: Phys. Rev. D 101, 041301 (R) (2020)
Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Theory (hep-th)
[103]  arXiv:1909.10268 (replaced) [pdf, other]
Title: Study of periodic signals from blazars
Authors: Gopal Bhatta
Comments: Published in Universe Proceedings, this https URL
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
[104]  arXiv:1909.10372 (replaced) [pdf, other]
Title: Neutron Star Structure in the Minimal Gravitational Standard-Model Extension and the Implication to Continuous Gravitational Waves
Comments: 9 pages, 2 figures; accepted by Physics Letters B
Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Phenomenology (hep-ph)
[105]  arXiv:1910.01070 (replaced) [pdf, other]
Title: Helios-r2 -- A new Bayesian, open-source retrieval model for brown dwarfs and exoplanet atmospheres
Comments: Accepted for publication in ApJ. The code is available under this https URL
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
[106]  arXiv:1910.02941 (replaced) [pdf, other]
Title: The aeolian-erosion barrier for the growth of metre-size objects in protoplanetary-discs
Comments: Comments are welcome, revised version
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
[107]  arXiv:1910.04179 (replaced) [pdf, other]
Title: The Redshift Evolution of Rest-UV Spectroscopic Properties to z~5
Comments: 20 pages, 17 figures, accepted for publication in MNRAS
Subjects: Astrophysics of Galaxies (astro-ph.GA)
[108]  arXiv:1910.07956 (replaced) [pdf, other]
Title: Design, operation and performance of the PAON4 prototype transit interferometer
Comments: 17 pages, 16 figures, accepted to MNRAS
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
[109]  arXiv:1910.08021 (replaced) [pdf, ps, other]
Title: Enhanced mass-loss rate evolution of stars with $\gtrsim 18 M_\odot$ and missing optically-observed type II core-collapse supernovae
Comments: New version after comments by the referee
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); High Energy Astrophysical Phenomena (astro-ph.HE)
[110]  arXiv:1910.14321 (replaced) [pdf, other]
Title: New Type of String Solutions with Long Range Forces
Comments: 27 pages, 7 figures, 1 table
Subjects: High Energy Physics - Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Theory (hep-th)
[111]  arXiv:1911.01983 (replaced) [pdf, other]
Title: Fast Neutrino Flavor Conversion Modes in Multidimensional Core-collapse Supernova Models: the Role of the Asymmetric Neutrino Distributions
Comments: Version accepted in PRD
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Theory (hep-th)
[112]  arXiv:1911.05394 (replaced) [pdf, other]
Title: Phase-space structure of cold dark matter halos inside splashback: multi-stream flows and self-similar solution
Comments: 18 pages, 14 figures, accepted for publication in MNRAS
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
[113]  arXiv:1911.06228 (replaced) [pdf, ps, other]
Title: The maximum turnaround radius for axisymmetric cosmic structures
Comments: v2, 15pp; added references and discussions; improved presentation
Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Theory (hep-th)
[114]  arXiv:1911.07091 (replaced) [pdf, other]
Title: Studying strong phase transitions in neutron stars with gravitational waves
Comments: 21 pages, 13 figures, 3 tables; accepted for publication in PRD, discussion on softer quark matter added, typos corrected
Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
[115]  arXiv:1911.07869 (replaced) [pdf, ps, other]
Title: Maximum Cosmological Information from Type-Ia Supernova Observations
Authors: Jaiyul Yoo (Zürich)
Comments: 7 pages, 3 figures, published in PRD
Journal-ref: Phys. Rev. D 101, 043507 (2020)
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
[116]  arXiv:1911.08198 (replaced) [pdf, other]
Title: The Nature of $γ$-ray Variability in Blazars
Comments: ApJ accepted 32 pages, 12 figures
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
[117]  arXiv:1912.05398 (replaced) [pdf, ps, other]
Title: Low energy core collapse supernovae in the frame of the jittering jets explosion mechanism
Comments: New version after comments by the referee
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
[118]  arXiv:1912.06691 (replaced) [pdf]
Title: Four Distinct Pathways to the Element Abundances in Solar Energetic Particles
Authors: Donald V. Reames
Comments: 30 pages, 13 figures, submitted to Space Sci. Rev
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)
[119]  arXiv:1912.07072 (replaced) [pdf, other]
Title: Non-linear statistics of primordial black holes from gaussian curvature perturbations
Comments: v2: improved discussions and citations. Constraint on the abundance related to minimums added. Discussion on the broad power spectrum and related appendix added. 19 pages, 5 figures
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th)
[120]  arXiv:1912.09081 (replaced) [pdf, other]
Title: Fast Luminous Blue Transients in the Reionization Era and Beyond
Comments: 6 pages, 5 figures added discussion in Sec 4. Accepted by ApJ Letters
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
[121]  arXiv:1912.11974 (replaced) [pdf, ps, other]
Title: Gamma-rays from kilonovae and the cosmic gamma-ray background
Authors: Pilar Ruiz-Lapuente (University of Barcelona), Oleg Korobkin (LANL)
Comments: Emulated ApJ, 9 Figures (accepted for publication in ApJ)
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
[122]  arXiv:1912.12469 (replaced) [pdf, ps, other]
Title: Weak Field Limit and Gravitational Waves in $f(T,B)$ Teleparallel Gravity
Comments: 14 pages, accepted for publication in Eur. Phys. J. C
Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Theory (hep-th)
[123]  arXiv:2001.03498 (replaced) [pdf, ps, other]
Title: The Faint Host Galaxies of C IV Absorbers at z > 5
Comments: 15 pages, 16 figures, resubmitted to MNRAS with improvements following first referee report
Subjects: Astrophysics of Galaxies (astro-ph.GA)
[124]  arXiv:2001.04474 (replaced) [pdf, other]
Title: On the possibility of GW190425 being a black hole--neutron star binary merger
Comments: 8 pages, 1 figure, matched to the published version with an additional reference
Journal-ref: Astrophys. J. 890, L4 (2020)
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc)
[125]  arXiv:2001.08147 (replaced) [pdf, other]
Title: GG Tau A: gas properties and dynamics from the cavity to the outer disk
Comments: 18 pages, 14 figures
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP); Astrophysics of Galaxies (astro-ph.GA)
[126]  arXiv:2001.10558 (replaced) [pdf, other]
Title: Solar-Metallicity Gas in the Extended Halo of a Galaxy at $z \sim 0.12$
Comments: 17 pages, 8 figures, 3 tables. Accepted for publication in MNRAS
Subjects: Astrophysics of Galaxies (astro-ph.GA)
[127]  arXiv:2001.11910 (replaced) [pdf, other]
Title: Gravitating cosmic superconducting tubes in the Einstein gauged non-linear sigma-model in (3+1)-dimensions
Comments: 26 pages, 9 figures
Subjects: High Energy Physics - Theory (hep-th); Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc)
[128]  arXiv:2002.00773 (replaced) [pdf, other]
Title: Understanding and Mitigating Biases when Studying Inhomogeneous Emission Spectra with JWST
Comments: Accepted for publication by MNRAS
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
[129]  arXiv:2002.01185 (replaced) [pdf, other]
Title: Combined search for anisotropic birefringence in the gravitational-wave transient catalog GWTC-1
Authors: Lijing Shao
Comments: 13 pages, 6 figures, 6 tables; submitted to Physical Review
Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc)
[130]  arXiv:2002.01488 (replaced) [pdf, other]
Title: Detection of Strong Epicyclic Density Spikes in the GD-1 Stellar Stream. An Absence of Evidence for the Influence of Dark Matter Subhalos?
Comments: 18 pages, 14 figures, accepted for publication in ApJ (some typos fixed)
Subjects: Astrophysics of Galaxies (astro-ph.GA)
[131]  arXiv:2002.01920 (replaced) [pdf, other]
Title: FRB-periodicity: mild pulsar in tight O/B-star binary
Authors: Maxim Lyutikov, Maxim Barkov, Dimitrios Giannios (Purdue University)
Comments: 13 pages, 4 figures
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
[132]  arXiv:2002.01943 (replaced) [pdf, other]
[133]  arXiv:2002.02104 (replaced) [pdf, ps, other]
Title: Magnetic Structure of an Erupting Filament
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)
[134]  arXiv:2002.02150 (replaced) [pdf, other]
Title: Towards a real-time fully-coherent all-sky search for gravitational waves from compact binary coalescences using particle swarm optimization
Comments: Fixed more typographical mistakes; Added more information in Fig 3. 13 pages, 12 figures
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); General Relativity and Quantum Cosmology (gr-qc)
[135]  arXiv:2002.02203 (replaced) [pdf, other]
Title: On the vortex evolution in non-isothermal protoplanetary discs
Comments: Accepted in MNRAS, 14 pages,8 figures, 1 table
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
[136]  arXiv:2002.02816 (replaced) [pdf, ps, other]
Title: The Aarhus red giants challenge II. Stellar oscillations in the red giant branch phase
Comments: Astronomy and Astrophysics, in the press. Paper resubmitted to arXiv to correct author list in metadata
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)
[137]  arXiv:2002.02822 (replaced) [pdf, other]
Title: The impact of AGN feedback on the 1D power spectra from the Ly$α$ forest using the Horizon-AGN suite of simulations
Comments: Submitted to MNRAS
Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
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