Astrophysics

New submissions

• New submissions
• Cross-lists
• Replacements

New submissions for Mon, 27 Jan 20

[1]  arXiv:2001.08748 [pdf]

Title: A Galactic-scale gas wave in the Solar Neighborhood

Authors: João Alves, Catherine Zucker, Alyssa A. Goodman, Joshua S. Speagle, Stefan Meingast, Thomas Robitaille, Douglas P. Finkbeiner, Edward F. Schlafly, Gregory M. Green

Comments: Published in Nature on 7 January 2020. For data, interactive visualizations, and more information see: this http URL (this https URL)

Journal-ref: Nature, 7 January 2020

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

For the past 150 years, the prevailing view of the local Interstellar Medium (ISM) was based on a peculiarity known as the Gould's Belt, an expanding ring of young stars, gas, and dust, tilted about 20$^\circ$ to the Galactic plane. Still, the physical relation between local gas clouds has remained practically unknown because the distance accuracy to clouds is of the same order or larger than their sizes. With the advent of large photometric surveys and the Gaia satellite astrometric survey this situation has changed. Here we report the 3-D structure of all local cloud complexes. We find a narrow and coherent 2.7 kpc arrangement of dense gas in the Solar neighborhood that contains many of the clouds thought to be associated with the Gould Belt. This finding is inconsistent with the notion that these clouds are part of a ring, disputing the Gould Belt model. The new structure comprises the majority of nearby star-forming regions, has an aspect ratio of about 1:20, and contains about 3 million solar masses of gas. Remarkably, the new structure appears to be undulating and its 3-D distribution is well described by a damped sinusoidal wave on the plane of the Milky Way, with an average period of about 2 kpc and a maximum amplitude of about 160 pc. Our results represent a first step in the revision of the local gas distribution and Galactic structure and offer a new, broader context to studies on the transformation of molecular gas into stars.

[2]  arXiv:2001.08749 [pdf, other]

Title: Anti-Deuterons and Anti-Helium Nuclei from Annihilating Dark Matter

Authors: Ilias Cholis, Tim Linden, Dan Hooper

Comments: 9 pages, 7 figures, 3 appendices

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

Recent studies of the cosmic-ray antiproton-to-proton ratio have identified an excess of $\sim$10-20 GeV antiprotons relative to the predictions of standard astrophysical models. Intriguingly, the properties of this excess are consistent with the same range of dark matter models that can account for the long-standing excess of $\gamma$-rays observed from the Galactic Center. Such dark matter candidates can also produce significant fluxes of anti-deuterium and anti-helium nuclei. Here we study the production and transport of such particles, both from astrophysical processes as well as from dark matter annihilation. Importantly, in the case of AMS-02, we find that Alfv\'{e}nic reacceleration (i.e., diffusion in momentum space) can boost the expected number of $\bar{\rm d}$ and ${}^{3}\overline{\textrm{He}}$ events from annihilating dark matter by an order of magnitude or more. For relatively large values of the Alfv\'{e}n speed, and for dark matter candidates that are capable of producing the antiproton and $\gamma$-ray excesses, we expect annihilations to produce a few anti-deuteron events and about one anti-helium event in six years of AMS-02 data. This is particularly interesting in light of recent reports from the AMS-02 Collaboration describing the detection of a number of anti-helium candidate events.

[3]  arXiv:2001.08751 [pdf, other]

Title: Semi-analytic forecasts for JWST -- IV. Implications for cosmic reionization and LyC escape fraction

Authors: L. Y. Aaron Yung, Rachel S. Somerville, Steven L. Finkelstein, Gregö Popping, Romeel Davé, Aparna Venkatesan, Peter Behroozi, Harry C. Ferguson

Comments: 21 pages, 15 figures, submitted to MNRAS, all comments welcome

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

Galaxies forming in low-mass halos are thought to be primarily responsible for reionizing the Universe during the first billion years after the Big Bang. Yet, these halos are extremely inefficient at forming stars in the nearby Universe. In this work, we address this apparent tension, and ask whether a physically motivated model of galaxy formation that reproduces the observed abundance of faint galaxies in the nearby Universe is also consistent with available observational constraints on the reionization history. By interfacing the Santa Cruz semi-analytic model for galaxy formation with an analytic reionization model, we constructed a computationally efficient pipeline that connects `ground-level' galaxy formation physics to `top-level' cosmological-scale observables. Based on photometric properties of the galaxy populations predicted up to $z=15$, we compute the reionization history of intergalactic hydrogen. We quantify the three degenerate quantities that influence the total ionizing photon budget, including the abundance of galaxies, the intrinsic production rate of ionizing photons, and the LyC escape fraction. We explore covariances between these quantities using a Markov chain Monte Carlo method. We find that our locally calibrated model is consistent with all currently available constraints on the reionization history, under reasonable assumptions about the LyC escape fraction. We quantify the fraction of ionizing photons contributed by galaxies of different luminosities and find that the galaxies expected to be detected in JWST NIRCam wide and deep surveys are responsible for producing $\sim 40$-$80\%$ of ionizing photons throughout the EoR. All results presented in this work are available at https://www.simonsfoundation.org/semi-analytic-forecasts-for-jwst/.

[4]  arXiv:2001.08752 [pdf, other]

Title: The Ultraluminous X-ray sources population of the galaxy NGC 7456

Authors: F. Pintore, M. Marelli, R. Salvaterra, G. L. Israel, G. A. Rodríguez Castillo, P. Esposito, A. Belfiore, A. De Luca, A. Wolter, S. Mereghetti, L. Stella, M. Rigoselli, H. P. Earnshaw, C. Pinto, T. P. Roberts, D. J. Walton, F. Bernardini, F. Haberl, C. Salvaggio, A. Tiengo, L. Zampieri, M. Bachetti, M. Brightman, P. Casella, D. D'Agostino, S. Dall'Osso, F. Fuerst, F. A. Harrison, M. Mapelli, A. Papitto, M. Middleton

Comments: Accepted on ApJ; 10 pages, 5 figures, 3 tables

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

Ultraluminous X-ray sources (ULXs) are a class of accreting compact objects with X-ray luminosities above 1e39 erg/s. The ULX population counts several hundreds objects but only a minor fraction is well studied. Here we present a detailed analysis of all ULXs hosted in the galaxy NGC 7456. It was observed in X-rays only once in the past (in 2005) by XMM-Newton, but the observation was short and strongly affected by high background. In 2018, we obtained a new, deeper (~90 ks) XMM-Newton observation that allowed us to perform a detailed characterization of the ULXs hosted in the galaxy. ULX-1 and ULX-2, the two brightest objects (Lx~(6-10)e39 erg/s), have spectra that can be described by a two-thermal component model as often found in ULXs. ULX-1 shows also one order of magnitude in flux variability on short-term timescales (hundreds to thousand ks). The other sources (ULX-3 and ULX-4) show flux changes of at least an order of magnitude, and these objects may be candidate transient ULXs although longer X-ray monitoring or further studies are required to ascribe them to the ULX population. In addition, we found a previously undetected source that might be a new candidate ULX (labelled as ULX-5) with a luminosity of ~1e39 erg/s and hard power-law spectral shape, whose nature is still unclear and for which a background Active Galactic Nucleus cannot be excluded. We discuss the properties of all the ULXs in NGC 7456 within the framework of super-Eddington accretion onto stellar mass compact objects. Although no pulsations were detected, we cannot exclude that the sources host neutron stars.

[5]  arXiv:2001.08753 [pdf, other]

Title: The MASSIVE Survey -- XV. A Stellar Dynamical Mass Measurement of the Supermassive Black Hole in Massive Elliptical Galaxy NGC 1453

Authors: Christopher M. Liepold, Matthew E. Quenneville, Chung-Pei Ma, Jonelle L. Walsh, Nicholas J. McConnell, Jenny E. Greene, John P. Blakeslee

Comments: 22 pages, 12 figures

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

We present a new stellar dynamical mass measurement ($M_\mathrm{BH}$) of the supermassive black hole (SMBH) in NGC 1453, a fast-rotating massive elliptical galaxy in the MASSIVE survey. We measure stellar kinematics in 135 spatial bins in the central 1.5 kpc by 2 kpc region of the galaxy using high signal-to-noise ($S/N \sim 130$) spectra from the Gemini-North GMOS integral-field spectrograph (IFS). Combining with wide-field IFS kinematics out to $\sim 3$ effective radii and stellar light distributions from Hubble Space Telescope (HST) WFC3 images, we perform Schwarzschild orbit-based mass modeling in the axisymmetric limit to constrain the mass components in NGC 1453. The best-fit black hole mass is $M_\mathrm{BH} =(2.9 \pm 0.4) 10^9 M_\odot$; the mass models without a central black hole are excluded at the $8.7\sigma$ level. The NGC 1453 black hole lies within the intrinsic scatter of the SMBH and galaxy scaling relations, unlike three other galaxies hosting $\gtrsim 10^{10} M_\odot$ SMBHs in the MASSIVE sample. The high-$S/N$ GMOS spectra enable us to determine 8 moments of the Gauss-Hermite expansion of the line-of-sight velocity distributions (LOSVDs), which are used as constraints in the orbit modeling. The stellar orbits in the mass models are further constrained to produce negligible $h_9$ through $h_{12}$ to minimize spurious behavior in the LOSVDs. We show that truncating the series at $h_4$, as was often done in prior work, leads to a much weaker constraint on the inferred $M_\mathrm{BH}$ for NGC 1453. Furthermore, we discuss precautions and modifications that are needed to achieve axisymmetry in triaxial orbit codes that use the Schwarzschild method to sample the start space of stellar orbits in triaxial gravitational potentials.

[6]  arXiv:2001.08754 [pdf, other]

Title: Signatures of Velocity-Dependent Dark Matter Self-Interactions in Milky Way-mass Halos

Authors: Ethan O. Nadler, Arka Banerjee, Susmita Adhikari, Yao-Yuan Mao, Risa H. Wechsler

Comments: 18 pages, 10 figures, 1 table; to be submitted to ApJ

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

We explore the impact of elastic, anisotropic, velocity-dependent dark matter (DM) self-interactions on the host halo and subhalos of Milky Way (MW)-mass systems. We consider a generic self-interacting dark matter (SIDM) model parameterized by the masses of a light mediator and the DM particle. The ratio of these masses, $w$, sets the velocity scale above which momentum transfer due to DM self-interactions becomes inefficient. We perform high-resolution zoom-in simulations of a MW-mass halo for values of $w$ that span scenarios in which self-interactions between either the host and its subhalos, or only within subhalos, efficiently transfer momentum, and we study the effects of self-interactions on the host halo and on the abundance, radial distribution, orbital dynamics, and density profiles of subhalos in each case. The abundance and properties of surviving subhalos are consistent with being determined primarily by subhalo--host halo interactions. In particular, subhalos on radial orbits in models with larger values of the cross section at the host halo velocity scale are more susceptible to tidal disruption due to mass loss from ram-pressure stripping caused by self-interactions with the host. This mechanism suppresses the abundance of surviving subhalos relative to collisionless DM simulations, with stronger suppression for larger values of $w$. Thus, probes of subhalo abundance around MW-mass hosts can be used to place upper limits on the self-interaction cross section at velocity scales of $\sim 200\ \rm{km\ s}^{-1}$, and combining these measurements with the inferred orbital properties and internal dynamics of subhalos may break degeneracies among velocity-dependent SIDM models.

[7]  arXiv:2001.08757 [pdf, ps, other]

Title: Constraining planet formation around 6$M_{\odot}$-8$M_{\odot}$ stars

Authors: Dimitri Veras, Pier-Emmanuel Tremblay, J.J. Hermes, Catriona H. McDonald, Grant M. Kennedy, Farzana Meru, Boris T. Gänsicke

Comments: Accepted for publication in MNRAS

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

Identifying planets around O-type and B-type stars is inherently difficult; the most massive known planet host has a mass of only about $3M_{\odot}$. However, planetary systems which survive the transformation of their host stars into white dwarfs can be detected via photospheric trace metals, circumstellar dusty and gaseous discs, and transits of planetary debris crossing our line-of-sight. These signatures offer the potential to explore the efficiency of planet formation for host stars with masses up to the core-collapse boundary at $\approx 8M_{\odot}$, a mass regime rarely investigated in planet formation theory. Here, we establish limits on where both major and minor planets must reside around $\approx 6M_{\odot}-8M_{\odot}$ stars in order to survive into the white dwarf phase. For this mass range, we find that intact terrestrial or giant planets need to leave the main sequence beyond approximate minimum star-planet separations of respectively about 3 and 6 au. In these systems, rubble pile minor planets of radii 10, 1.0, and 0.1 km would have been shorn apart by giant branch radiative YORP spin-up if they formed and remained within, respectively, tens, hundreds and thousands of au. These boundary values would help distinguish the nature of the progenitor of metal-pollution in white dwarf atmospheres. We find that planet formation around the highest mass white dwarf progenitors may be feasible, and hence encourage both dedicated planet formation investigations for these systems and spectroscopic analyses of the highest mass white dwarfs.

[8]  arXiv:2001.08758 [pdf, other]

Title: A review of quasi-periodic oscillations from black hole X-ray binaries: observation and theory

Authors: Adam Ingram, Sara Motta

Comments: Accepted for publication in New Astronomy Reviews; 67 pages, 22 figures

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

Black hole and neutron star X-ray binary systems routinely show quasi-periodic oscillations (QPOs) in their X-ray flux. Despite being strong, easily measurable signals, their physical origin has long remained elusive. However, recent observational and theoretical work has greatly improved our understanding. Here, we briefly review the basic phenomenology of the different varieties of QPO in both black hole and neutron star systems before focusing mainly on low frequency QPOs in black hole systems, for which much of the recent progress has been made. We describe the detailed statistical properties of these QPOs and review the physical models proposed in the literature, with particular attention to those based on Lense-Thirring precession. This is a relativistic effect whereby a spinning massive object twists up the surrounding spacetime, inducing nodal precession in inclined orbits. We review the theory describing how an accretion flow reacts to the Lense-Thirring effect, including analytic theory and recent numerical simulations. We then describe recent observational tests that provide very strong evidence that at least a certain type of low frequency QPOs are a geometric effect, and good evidence that they are the result of precession. We discuss the possibility of the spin axis of the compact object being misaligned with the binary rotation axis for a large fraction of X-ray binaries, as is required for QPOs to be driven specifically by Lense-Thirring precession, as well as some outstanding gaps in our understanding and future opportunities provided by X-ray polarimeters and/or high throughput X-ray detectors.

[9]  arXiv:2001.08760 [pdf, other]

Title: Voronoi volume function: A new probe of cosmology and galaxy evolution

Authors: Aseem Paranjape (IUCAA), Shadab Alam (ROE)

Comments: 19 pages, 14 figures; submitted to MNRAS

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

We study the Voronoi volume function (VVF) -- the distribution of cell volumes in the Voronoi tessellation of any set of cosmological tracers (galaxies/haloes). We show that the shape of the VVF of biased tracers responds sensitively to physical properties such as halo mass, large-scale environment, substructure and redshift-space effects, making this a hitherto unexplored probe of both primordial cosmology and galaxy evolution. Using convenient summary statistics -- the width, median and a low percentile of the VVF as functions of tracer number density -- we explore these effects using tessellations of tracers selected by various criteria in a suite of N-body simulations of a range of dark matter models. We find that our summary statistics are sensitive probes of primordial features such as small-scale oscillations in the initial matter power spectrum (as arise in models involving collisional effects in the dark sector), while being largely insensitive to a truncation of initial power (as in warm dark matter models). For vanilla cold dark matter (CDM) cosmologies, the summary statistics display strong redshift evolution and redshift-space effects, and are also sensitive to cosmological parameter values for realistic tracer samples. Comparing the VVF of galaxies in the GAMA survey with that of abundance matched CDM (sub)haloes tentatively reveals environmental effects in GAMA beyond halo mass (modulo unmodelled satellite properties). Our exploratory analysis thus paves the way for using the VVF as a new probe of galaxy evolution physics as well as the nature of dark matter and dark energy.

[10]  arXiv:2001.08761 [pdf, other]

Title: Simultaneous magnetic polar cap heating during a flaring episode from the magnetar 1RXS J170849.0-400910

Authors: George Younes (1), Matthew G. Baring (2), Chryssa Kouveliotou (1), Zorawar Wadiasingh (3), Daniela Huppenkothen (4), Alice K. Harding (3) ((1) The George Washington University, Washington, DC 20052, USA, (2) Rice University, MS-108, P.O. Box 1892, Houston, TX 77251, USA, (3) Astrophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771, (4) University of Washington, 3910 15th Avenue NE, Seattle, WA 98195, USA)

Comments: Accepted for publication in the Astrophysical Journal Letters

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

During a pointed 2018 NuSTAR observation, we detected a flare with a 2.2 hour duration from the magnetar 1RXS J170849.0$-$400910. The flare, which rose in $\sim25$ seconds to a maximum flux 6 times larger than the persistent emission, is highly pulsed with an rms pulsed fraction of $53\%$. The pulse profile shape consists of two peaks separated by half a rotational cycle, with a peak flux ratio of $\sim$2. The flare spectrum is thermal with an average temperature of 2.1 keV. Phase resolved spectroscopy show that the two peaks possess the same temperature, but differ in size. These observational results along with simple light curve modeling indicate that two identical antipodal spots, likely the magnetic poles, are heated simultaneously at the onset of the flare and for its full duration. Hence, the origin of the flare has to be connected to the global dipolar structure of the magnetar. This might best be achieved externally, via twists to closed magnetospheric dipolar field lines seeding bombardment of polar footpoint locales with energetic pairs. Approximately 1.86 hours following the onset of the flare, a short burst with its own 3-minute thermal tail occurred. The burst tail is also pulsating at the spin period of the source and phase-aligned with the flare profile, implying an intimate connection between the two phenomena. The burst may have been caused by a magnetic reconnection event in the same twisted dipolar field lines anchored to the surface hot spots, with subsequent return currents supplying extra heat to these polar caps.

[11]  arXiv:2001.08765 [pdf, other]

Title: Selection of highly-accreting quasars: Spectral properties of FeII emitters not belonging to extreme Population A

Authors: N. Bon, P. Marziani, E. Bon, C.A. Negrete, D. Dultzin, A. del Olmo, M. D'Onofrio, M.L. Martinez-Aldama

Comments: 28 pages, 16 figures, accepted for publication in A&A

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

The quasar class of extreme Population A (xA) (also known as super-Eddington accreting massive black holes, SEAMBHs) has been hailed as potential distance indicators for cosmology. The aim of this paper is to define tight criteria for their proper identification starting from the main selection criterion $R_{FeII} > 1 $, and to identify potential intruders not meeting the selection criteria, but nonetheless selected as xA because of the coarseness of automatic searches. Inclusion of the spurious xA sources may dramatically increase the dispersion in the Hubble diagram of quasars obtained from virial luminosity estimates. We studied a sample of 32 low-$z$ quasars originally selected from the SDSS DR7 as xA. All of them show moderate-to-strong FeII emission and the wide majority strong absorption features in their spectra are typical of fairly evolved stellar populations. We performed a simultaneous fit of a host galaxy spectrum, AGN continuum, FeII template and emission lines to spectra, using the fitting technique based on ULySS, full spectrum fitting package. For sources in our sample (of spectral types corresponding to relatively low Eddington ratio), we found an overall consistency between narrow components of H$\beta$ and [OIII]$\lambda\lambda$4959, 5007 line shifts and the mean stellar velocity obtained from the host galaxy fit (within $\lesssim |60|$ km/s). Only one source in our sample qualify as xA source. We found high fraction of host galaxy spectrum (in half of the sample even higher then 40\%). When absorption lines are prominent, and the fraction of the host galaxy is high, SSP is mimicking FeII, and that may result in a mistaken identification of FeII spectral features. We have identified several stellar absorption lines that, along with the continuum shape, may lead to an overestimate of $R_{FeII}$, and therefore to the misclassification of sources as xA sources.

[12]  arXiv:2001.08770 [pdf, ps, other]

Title: Wind-reprocessed Transients

Authors: Anthony L. Piro (Carnegie Observatories), Wenbin Lu (Caltech)

Comments: 13 pages, 7 figures, submitted for publication in ApJ

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

We consider the situation where the luminosity from a transient event is reprocessed by an optically thick wind. Potential applications are the tidal disruption of stars by black holes, engine-powered supernovae, and unique fast transients found by current and future wide-field surveys. We derive relations between the injected and observed luminosity for steady and time dependent winds, and discuss how the temperature is set for scattering-dominated radiative transport. We apply this framework to specific examples of tidal disruption events and the formation of a black hole by a massive star, as well as discuss other applications such as deriving observables from detailed hydrodynamic simulations. We conclude by exploring what is inferred about the mass loss rate and underlying engine powering AT2018cow if it is explained as a wind-reprocessed transient, demonstrating that its optical emission is consistent with reprocessing of the observed soft X-rays.

[13]  arXiv:2001.08772 [pdf, other]

Title: PKS 2250$-$351: A Giant Radio Galaxy in Abell 3936

Authors: N. Seymour (1), M. Huynh (2,3), S.S. Shabala (4), J. Rogers (4), L.J.M. Davies (3), R.J. Turner (4), A. O'Brien (5), C.H. Ishwara-Chandra (6), J.E. Thorne (3), T.J. Galvin (2), T. Jarrett (7), H. Andernach (8), C. Anderson (2), J. Bunton (5), K. Chow (5), J.D. Collier (9,10), S. Driver (3), M. Filipovic (9), G. Gürkan (2), A. Hopkins (11), A.D. Kapińska (12), D.A. Leahy (13), J. Marvil (12), P. Manojlovic (10,5), R.P. Norris (10,5), C. Phillips (5), A. Robotham (3), L. Rudnick (14), V.S. Singh (15), S.V. White (1,16) ((1) ICRAR/Curtin University, (2) CSIRO Astronomy and Space Science, (3) ICRAR/UWA, (4) University of Tasmania, (5) CSIRO Astronomy and Space Science, (6) National Centre for Radio Astrophysics, (7) University of Cape Town, (8) Universidad de Guanajuato, (9) The Inter-University Institute for Data Intensive Astronomy, (10) Western Sydney University, (11) AAO-Macquarie, (12) National Radio Astronomy Observatory, (13) University of Calgary, (14) University of Minnesota, (15) Physical Research Laboratory, (16) Rhodes University)

Comments: 16 pages and 8 figures, accepted for publication in PASA

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

We present a detailed analysis of the radio galaxy PKS 2250-351, a giant of 1.2 Mpc projected size, its host galaxy, and its environment. We use radio data from the Murchison Widefield Array, the upgraded Giant Metre-wavelength Radio Telescope, the Australian Square Kilometre Array Pathfinder, and the Australia Telescope Compact Array to model the jet power and age. Optical and infra-red data come from the Galaxy And Mass Assembly (GAMA) survey and provide information on the host galaxy and environment. GAMA spectroscopy confirms that PKS 2250-351 lies at z=0.2115 in the irregular, and likely unrelaxed, cluster Abell 3936. We find its host is a massive, `red and dead' elliptical galaxy with negligible star formation but with a highly obscured active galactic nucleus dominating the mid-infrared emission. Assuming it lies on the local M-sigma relation it has an Eddington accretion rate of lambda_EDD~0.014. We find that the lobe-derived jet power (a time-averaged measure) is an order of magnitude greater than the hotspot-derived jet power (an instantaneous measure). We propose that over the lifetime of the observed radio emission (~300 Myr) the accretion has switched from an inefficient advection dominated mode to a thin-disc efficient mode, consistent with the decrease in jet power. We also suggest that the asymmetric radio morphology is due to its environment, with the host of PKS 2250-351 lying to the west of the densest concentration of galaxies in Abell 3936.

[14]  arXiv:2001.08782 [pdf, other]

Title: AT 2019abn: multi-wavelength observations of the first 200 days

Authors: S. C. Williams, D. Jones, P. Pessev, S. Geier, R. L. M. Corradi, I. M. Hook, M. J. Darnley, O. Pejcha, A. Núñez, S. Meingast, S. Moran

Comments: accepted for publication in A&A

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

AT 2019abn was discovered in the nearby M51 galaxy, by the Zwicky Transient Facility more than two magnitudes, and around 3 weeks, prior to its optical peak. We aimed to conduct a detailed photometric and spectroscopic follow-up campaign for AT 2019abn, with the early discovery allowing significant pre-maximum observations of an intermediate luminosity red transient (ILRT) for the first time. This work is based around the analysis of u'BVr'i'z'H photometry and low-resolution spectroscopy with the Liverpool Telescope, medium-resolution spectroscopy with Gran Telescopio Canarias (GTC) and near-infrared imaging with GTC and the Nordic Optical Telescope. We present the most detailed optical light curve of an ILRT to date, with multi-band photometry starting around three weeks before peak brightness. The transient peaked at an observed absolute magnitude of M_r=-13.1, although it is subject to significant reddening from dust in M51, implying an intrinsic M_r~-15.2. The initial light curve showed a linear, achromatic rise in magnitude, before becoming bluer at peak. After peak brightness the transient gradually cooled. This is reflected in our spectra which at later times show absorption from species such as Fe I, Ni I and Li I. A spectrum taken around peak brightness shows narrow, low-velocity absorption lines, which we interpret as likely originating from pre-existing circumstellar material. We conclude that, while there are some peculiarities, such as the radius evolution, AT 2019abn overall fits in well with the ILRT class of objects, and is the most luminous member of the class seen to date.

[15]  arXiv:2001.08784 [pdf, other]

Title: Baldwin Effect and Additional BLR Component in AGN with Superluminal Jets

Authors: V. M. Patiño-Ávarez, J. Torrealba, V. Chavushyan, I. Cruz-González, T. Arshakian, J. León-Tavares, L. Č. Popović

Comments: One column, 19 pages, 8 figures, 2 Tables, Published in Frontiers in Astronomy and Space Sciences

Journal-ref: Pati\~no-\'Alvarez et al. (2016), Front. Astron. Space Sci. (FrASS) 3:19

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

We study the Baldwin Effect (BE) in 96 core-jet blazars with optical and ultraviolet spectroscopic data from a radio-loud AGN sample obtained from the MOJAVE 2 cm survey. A statistical analysis is presented of the equivalent widths ($W_{\lambda}$) of emission lines H$\beta\,\lambda$4861, Mg II\,$\lambda$2798, C IV\,$\lambda$1549, and continuum luminosities at 5100\,\AA, 3000\,\AA, and 1350\,\AA. The BE is found statistically significant (with confidence level \textit{c.l.} $\geq\,$ 95\%) in H$\beta$ and C IV emission lines, while for Mg II the trend is slightly less significant (\textit{c.l.} = 94.5\%). The slopes of the BE in the studied samples for H$\beta$ and Mg II are found steeper and with statistically significant difference than those of a comparison radio-quiet sample. We present simulations of the expected BE slopes produced by the contribution to the total continuum of the non-thermal boosted emission from the relativistic jet, and by variability of the continuum components. We find that the slopes of the BE between radio-quiet and radio-loud AGN should not be different, under the assumption that the broad line is only being emitted by the canonical broad line region around the black hole. We discuss that the BE slope steepening in radio AGN is due to a jet associated broad-line region.

[16]  arXiv:2001.08786 [pdf, ps, other]

Title: The orbital clusters among the near Earth asteroids

Authors: Tadeusz J. Jopek

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

Fifteen orbital clusters (associations) were identified among 20000 near Earth asteroids (NEAs). All associations were found with a high statistical reliability, we used a single linkage cluster analysis algorithm and three orbital similarity functions. Identified groups are small fraction (4.74 percent) of the whole sample. However they could be hazardous to the Earth and its inhabitants. Every year similarly as it happens with meteoroid streams, the Earth comes very close to the orbits of each association. In two cases (2008TC3 and 2017FU102) the distance between the asteroid orbit and the Earth's orbit was smaller than the radius of our planet. Among members of the identified associations we found 331 objects larger than the Chelyabinsk asteroid and all these objects approach the Earth's orbit at a distance smaller than 0.05 au. Two of the identified groups (4179) Toutatis and (251430) Itokawa, proved to be in favor of a catastrophic origin of Toutatis and Itokawa asteroids. In this study we were not interested in the origin of the identified groups. However, regardless of their origin, in view of the serious thread to the Earth, tracing the NEA associations is very important issue. To facilitate their monitoring of we have calculated coordinates of the theoretical radiants and calendar date of their potential activity.

[17]  arXiv:2001.08787 [pdf, other]

Title: The Websky Extragalactic CMB Simulations

Authors: George Stein, Marcelo A. Alvarez, J. Richard Bond, Alexander van Engelen, Nicholas Battaglia

Comments: 38 pages, 11 figures, 2 tables. Submitted to JCAP

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

We present a new pipeline for the efficient generation of synthetic observations of the extragalactic microwave sky, tailored to large ground-based CMB experiments such as the Simons Observatory, Advanced ACTPol, SPT-3G, and CMB-S4. Such simulated observations are a key technical challenge in cosmology because of the dynamic range and accuracy required. The first part of the pipeline generates a random cosmological realization in the form of a dark matter halo catalog and matter displacement field, as seen from a given position. The halo catalog and displacement field are modeled with ellipsoidal collapse dynamics and Lagrangian perturbation theory, respectively. In the second part, the cosmological realization is converted into a set of intensity maps over the range 10 - 10^3 GHz using models based on existing observations and hydrodynamical simulations. These maps include infrared emission from dusty star forming galaxies (CIB), Comptonization of CMB photons by hot gas in groups and clusters through the thermal Sunyaev-Zel'dovich effect (tSZ), Doppler boosting by Thomson scattering of the CMB by bulk flows through the kinetic Sunyaev-Zel'dovich effect (kSZ), and weak gravitational lensing of primary CMB anisotropies by the large-scale distribution of matter in the universe. After describing the pipeline and its implementation, we present the Websky maps, created from a realization of the cosmic web on our past light cone in the redshift interval 0<z<4.6 over the full-sky and a volume of ~(600 Gpc/h)^3 resolved with ~10^12 resolution elements. The Websky maps and halo catalog are publicly available at mocks.cita.utoronto.ca/websky.

[18]  arXiv:2001.08790 [pdf, other]

Title: The MUSE-Faint survey: I. Spectroscopic evidence for a star cluster in Eridanus 2 and constraints on MACHOs as a constituent of dark matter

Authors: Sebastiaan L. Zoutendijk (1), Jarle Brinchmann (2 and 1), Leindert A. Boogaard (1), Madusha L. P. Gunawardhana (1), Tim-Oliver Husser (3), Sebastian Kamann (4), Andrés Felipe Ramos Padilla (1), Martin M. Roth (5), Roland Bacon (6), Mark den Brok (5), Stefan Dreizler (3), Davor Krajnović (5), The MUSE Collaboration ((1) Leiden Observatory, Leiden University, Leiden, The Netherlands, (2) Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto, CAUP, Porto, Portugal, (3) Institute for Astrophysics, Georg-August-University, Göttingen, Germany, (4) Astrophysics Research Institute, Liverpool John Moores University, Liverpool, United Kingdom, (5) Leibniz-Institut für Astrophysik Potsdam (AIP), Potsdam, Germany, (6) Univ. Lyon, Univ. Lyon1, ENS de Lyon, CNRS, Centre de Recherche Astrophysique de Lyon, Saint-Genis-Laval, France)

Comments: 17 pages, 12 figures, 3 tables. 1 electronic table included in source. Accepted for publication in A&A

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

We aim to provide spectroscopic evidence regarding the nature of the putative star cluster in Eridanus 2 and to place constraints on the mass and abundance of massive astrophysical compact halo objects (MACHOs) as a constituent of dark matter. Methods. We present spectroscopic observations of the central square arcminute of Eridanus 2 from MUSE-Faint, a survey of ultra-faint dwarf galaxies with the Multi Unit Spectroscopic Explorer on the Very Large Telescope. We derive line-of-sight velocities for possible member stars of the putative cluster and for stars in the centre of Eridanus 2. We discuss the existence of the cluster and determine new constraints for MACHOs using the Fokker-Planck diffusion approximation. Results. Out of 182 extracted spectra, we identify 26 member stars of Eridanus 2, seven of which are possible cluster members. We find intrinsic mean line-of-sight velocities of $79.7^{+3.1}_{-3.8}\,\mathrm{km}\,\mathrm{s}^{-1}$ and $76.0^{+3.2}_{-3.7}\,\mathrm{km}\,\mathrm{s}^{-1}$ for the cluster and the bulk of Eridanus 2, respectively, and intrinsic velocity dispersions of ${<}7.6\,\mathrm{km}\,\mathrm{s}^{-1}$ (68-$\%$ upper limit) and $10.3^{+3.9}_{-3.2}\,\mathrm{km}\,\mathrm{s}^{-1}$, respectively. This indicates the cluster most likely exists as a distinct dynamical population hosted by Eridanus 2, without surplus of dark matter over the background distribution. Among the member stars in the bulk of Eridanus 2, we find possible carbon stars, alluding to the existence of an intermediate-age population. We derive constraints on the fraction of dark matter that can consist of MACHOs with a given mass between $1$-$10^5\,M_\mathrm{sun}$. For dark matter consisting purely of MACHOs, the mass of the MACHOs must be less than ${\sim}7.6\,M_\mathrm{sun}$ and ${\sim}44\,M_\mathrm{sun}$ at a $68$- and $95$-$\%$ confidence level, respectively. (Abridged)

[19]  arXiv:2001.08792 [pdf, other]

Title: Characterizing $r$-Process Sites through Actinide Production

Authors: Erika M. Holmbeck, Rebecca Surman, Anna Frebel, G. C. McLaughlin, Matthew R. Mumpower, Trevor M. Sprouse, Toshihiko Kawano, Nicole Vassh, Timothy C. Beers

Comments: 12 pages, 5 figures, NPA-IX proceedings

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

Of the variations in the elemental abundance patterns of stars enhanced with $r$-process elements, the variation in the relative actinide-to-lanthanide ratio is among the most significant. We investigate the source of these actinide differences in order to determine whether these variations are due to natural differences in astrophysical sites, or due to the uncertain nuclear properties that are accessed in $r$-process sites. We find that variations between relative stellar actinide abundances is most likely astrophysical in nature, owing to how neutron-rich the ejecta from an $r$-process event may be. Furthermore, if an $r$-process site is capable of generating variations in the neutron-richness of its ejected material, then only one type of $r$-process site is needed to explain all levels of observed relative actinide enhancements.

[20]  arXiv:2001.08798 [pdf, ps, other]

Title: The quadruple system HIP 45734

Authors: Andrei Tokovinin

Comments: Accepted by Astronomical Journal; 9 pages, 8 figures, 8 tables

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

HIP 45734 is a quadruple system of 2+2 architecture located at 68 pc from the Sun. The outer 9" system A,B has a period of ~10^4 yr. The pair Aa,Ab is a visual binary with a period of 20.1 years and an eccentricity of 0.78. Its periastron in 2019.1 was observed spectroscopically, yielding masses (1.10+-0.04 and 0.98+-0.03 M_sun) and orbital parallax, 14.90+-0.37 mas. The masses, luminosities, and colors approximately agree with evolutionary models of main sequence stars. The component Aa has a detectable lithium line, whereas in Ab it is absent. The pair Ba,Bb is a single-lined spectroscopic binary with a period of 0.55552 day and an orbital inclination of ~45 deg derived by modeling the rotationally broadened line profile with ``flat bottom''. The mass of Bb is ~0.4 M_sun. The star B is chromospherically active (an x-ray source); its flux is modulated with the orbital period by starspots, in addition to occasional flares. The system is probably older than ~600 Myr; it does not belong to any known moving group.

[21]  arXiv:2001.08811 [pdf, other]

Title: The energy spectrum of ultra-high energy cosmic rays measured at the Pierre Auger Observatory and at the Telescope Array

Authors: O. Deligny (for the Pierre Auger and Telescope Array Collaborations)

Comments: Proceedings of 36th International Cosmic Ray Conference

Journal-ref: PoS(ICRC2019)234

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

The energy spectrum of ultra-high energy cosmic rays (UHECRs) provides essential information on the most energetic phenomena in the Universe. Beyond EeV energies, the Telescope Array and Pierre Auger Observatory have the largest exposures to UHECRs ever accumulated in the Northern and Southern hemispheres, respectively. The results show independently a steepening of the energy spectrum above a few tens of EeV. However, the comparison of the spectra shows differences that are not explainable in terms of an overall uncertainty on the energy scale used to reconstruct the extensive air showers. The differences are also observed in the region of the sky covered by both instruments, where the spectra should be in agreement within uncertainties when directional-exposure effects are accounted for. For this contribution, a working group from both collaborations examined these differences considering the energy-dependent systematic uncertainties. A special focus is given to the characterization of the spectral features, which provide an accurate tool to enhance our understanding of the comparisons.

[22]  arXiv:2001.08814 [pdf, other]

Title: Predictions for the 21cm-galaxy cross-power spectrum observable with SKA and future galaxy surveys

Authors: Dijana Vrbanec (Max Planck Institute for Astrophysics), Benedetta Ciardi (Max Planck Institute for Astrophysics), Vibor Jelic (Ruder Boskovic Institute), Hannes Jensen (Stockholm University), Ilian T. Iliev (University of Sussex), Garrelt Mellema (Stockholm University), Saleem Zaroubi (University of Groningen, Open University of Israel, The Technion)

Comments: 8 pages, 8 figures, accepted for publication in MNRAS

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

In this paper we use radiative transfer + N-body simulations to explore the feasibility of measurements of cross-correlations between the 21cm field observed by the Square Kilometer Array (SKA) and high-z Lyman Alpha Emitters (LAEs) detected in galaxy surveys with the Subaru Hyper Supreme Cam (HSC), Subaru Prime Focus Spectrograph (PFS) and Wide Field Infrared Survey Telescope (WFIRST). 21cm-LAE cross-correlations are in fact a powerful probe of the epoch of reionization as they are expected to provide precious information on the progress of reionization and the typical scale of ionized regions at different redshifts. The next generation observations with SKA will have a noise level much lower than those with its precursor radio facilities, introducing a significant improvement in the measurement of the cross-correlations. We find that an SKA-HSC/PFS observation will allow to investigate scales below ~10 Mpc/h and ~60 Mpc/h at z=7.3 and 6.6, respectively. WFIRST will allow to access also higher redshifts, as it is expected to observe spectroscopically ~900 LAEs per square degree and unit redshift in the range 7.5<z<8.5. Because of the reduction of the shot noise compared to HSC and PFS, observations with WFIRST will result in more precise cross-correlations and increased observable scales.

[23]  arXiv:2001.08834 [pdf, other]

Title: Mass determinations of the three mini-Neptunes transiting TOI-125

Authors: L.D. Nielsen, D. Gandolfi, D.J. Armstrong, J.S. Jenkins, M. Fridlund, N.C. Santos, F. Dai, V. Adibekyan, R. Luque, J.H. Steffen, M. Esposito, F. Meru, S. Sabotta, E. Bolmont, D. Kossakowski, J.F. Otegi, F. Murgas, M. Stalport, F.~Rodler, M.R. Díaz, N.T.~Kurtovic, G. Ricker, R. Vanderspek, D.W. Latham, S. Seager, J.N. Winn, J.M. Jenkins, R. Allart J.M.~Almenara D. Barrado, S.C.C. Barros, D. Bayliss, Z.M. Berdiñas, I. Boisse, F. Bouchy, P. Boyd, D.J.A. Brown, E.M. Bryant, C. Burke, W.D. Cochran, B.F. Cooke, O.D.S. Demangeon, R.F. Díaz, J. Dittman, C. Dorn, X. Dumusque, R. A. García, L. González-Cuesta, S. Grziwa, I. Georgieva, N. Guerrero, A.P. Hatzes, R. Helled, C.E. Henze, S. Hojjatpanah, J. Korth, K.W.F.~Lam, J.~Lillo-Box, T.A. Lopez, J. Livingston, S. Mathur, O. Mousis, et al. (20 additional authors not shown)

Comments: Accepted for publication in MNRAS

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

The Transiting Exoplanet Survey Satellite, TESS, is currently carrying out an all-sky search for small planets transiting bright stars. In the first year of the TESS survey, steady progress was made in achieving the mission's primary science goal of establishing bulk densities for 50 planets smaller than Neptune. During that year, TESS's observations were focused on the southern ecliptic hemisphere, resulting in the discovery of three mini-Neptunes orbiting the star TOI-125, a V=11.0 K0 dwarf. We present intensive HARPS radial velocity observations, yielding precise mass measurements for TOI-125b, TOI-125c and TOI-125d. TOI-125b has an orbital period of 4.65 days, a radius of $2.726 \pm 0.075 ~\mathrm{R_{\rm E}}$, a mass of $ 9.50 \pm 0.88 ~\mathrm{M_{\rm E}}$ and is near the 2:1 mean motion resonance with TOI-125c at 9.15 days. TOI-125c has a similar radius of $2.759 \pm 0.10 ~\mathrm{R_{\rm E}}$ and a mass of $ 6.63 \pm 0.99 ~\mathrm{M_{\rm E}}$, being the puffiest of the three planets. TOI-125d, has an orbital period of 19.98 days and a radius of $2.93 \pm 0.17~\mathrm{R_{\rm E}}$ and mass $13.6 \pm 1.2 ~\mathrm{M_{\rm E}}$. For TOI-125b and TOI-125d we find unusual high eccentricities of $0.19\pm 0.04$ and $0.17^{+0.08}_{-0.06}$, respectively. Our analysis also provides upper mass limits for the two low-SNR planet candidates in the system; for TOI-125.04 ($R_P=1.36 ~\mathrm{R_{\rm E}}$, $P=$0.53 days) we find a $2\sigma$ upper mass limit of $1.6~\mathrm{M_{\rm E}}$, whereas TOI-125.05 ( $R_P=4.2^{+2.4}_{-1.4} ~\mathrm{R_{\rm E}}$, $P=$ 13.28 days) is unlikely a viable planet candidate with upper mass limit $2.7~\mathrm{M_{\rm E}}$. We discuss the internal structure of the three confirmed planets, as well as dynamical stability and system architecture for this intriguing exoplanet system.

[24]  arXiv:2001.08843 [pdf, other]

Title: Gamma-ray spectrometry in the cutoff region as a key for the understanding of radiation processes in 3C 279

Authors: Davit Zargaryan, Carlo Romoli, Felix Aharonian

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

We present results of spectrometric studies based on the observations of very strong 3C 279 flares in high and very-high-energy bands and discuss their implications regarding the origin of radiation mechanisms. The FSRQ 3C 279 (z=0.536) is one of the most luminous gamma-ray emitting AGN. It shows variability on time scales down to minutes during strong flares detected by the Fermi-LAT. We have analyzed LAT and Swift-XRT data for the flaring periods in June 2015 and January 2018, when the flux above 100 MeV during hourly time intervals could exceed $3 \times 10^{-5}$ ph cm$^{-2}$ s$^{-1}$. The X-ray flux derived from Swift X-ray observations described by a very hard spectrum with photon index ~1.5 is typically explained by Inverse Compton scattering of low energy electrons and protons. Here we consider an alternative interpretation which describes the entire band from X-ray to very high energy as a results of synchrotron emission by ultra relativistic electrons or protons.

[25]  arXiv:2001.08863 [pdf, ps, other]

Title: A tight correlation between the enclosed gravitational mass and hot gas mass in galaxy clusters at intermediate radii

Authors: Man Ho Chan

Comments: Accepted in Physics of the Dark Universe

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

Many studies point out that there exists some tight correlations between dark matter and baryonic matter at different radii in galaxies. However, similar tight correlations can only be found in galaxy clusters for large radii. Here we report extremely tight correlations between the gravitational mass $M_{\rm grav}$ and hot gas mass $M_{\rm gas}$ in galaxy clusters at the hot gas core radius $r_c$ and at $2r_c$ (i.e. $M_{\rm grav}(r_c)$ vs $M_{\rm gas}(r_c)$ and $M_{\rm grav}(2r_c)$ vs $M_{\rm gas}(2r_c)$). By using the X-ray data of 64 large galaxy clusters with different sizes and masses, we find that the correlations can be described by a single relation $\log(M_{\rm grav}/M_{\odot})=(0.74 \pm 0.02) \log(M_{\rm gas}/M_{\odot})+(4.47 \pm 0.23)$ for a wide range of hot gas mass ($10^{11}M_{\odot}-10^{14}M_{\odot}$). The corresponding correlation coefficient and scatter are 0.97 and 0.10 dex respectively. This would be the first tight correlation with very small scatter between the enclosed gravitational mass and hot gas mass for galaxy clusters within intermediate radii ($\sim 100-1000$ kpc) and it provides a new kind of observational evidence to support the universality of correlation between dark matter and baryons.

[26]  arXiv:2001.08870 [pdf, other]

Title: Chandra Observations of Candidate Sub-Parsec Binary Supermassive Black Holes

Authors: M. Lynne Saade, Daniel Stern, Murray Brightman, Zoltán Haiman, S.G. Djorgovski, Daniel D'Orazio, K.E.S. Ford, Matthew J. Graham, Hyunsung D. Jun, Ralph P. Kraft, Barry McKernan, Alexei Vikhlinin, Dominic J. Walton

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

We present analysis of Chandra X-ray observations of seven quasars that were identified as candidate sub-parsec binary supermassive black hole (SMBH) systems in the Catalina Real-Time Transient Survey (CRTS) based on apparent periodicity in their optical light curves. Simulations predict close-separation accreting SMBH binaries will have different X-ray spectra than single accreting SMBHs, including harder or softer X-ray spectra, ripple-like profiles in the Fe K-$\alpha$ line, and distinct peaks in the spectrum due to the separation of the accretion disk into a circumbinary disk and mini-disks around each SMBH. We obtained Chandra observations to test these models and assess whether these quasars could contain binary SMBHs. We instead find that the quasar spectra are all well fit by simple absorbed power law models, with the rest frame 2-10 keV photon indices, $\Gamma$, and the X-ray-to-optical power slopes, $\alpha_{\rm OX}$, indistinguishable from the larger quasar population. This may indicate that these seven quasars are not truly sub-parsec binary SMBH systems, or it may simply reflect that our sample size was too small to robustly detect any differences. Alternatively, the X-ray spectral changes might only be evident at higher energies than probed by Chandra. Given the available models and current data, no firm conclusions are drawn. These observations will help motivate and direct further work on theoretical models of binary SMBH systems, such as modeling systems with thinner accretion disks and larger binary separations.

[27]  arXiv:2001.08890 [pdf, ps, other]

Title: Sporadic and intense accretion in a 1 Myr-old brown dwarf candidate

Authors: D. Nguyen-Thanh, N. Phan-Bao, S. J. Murphy, M. S. Bessell

Comments: 17 pages, 11 figures, accepted for publication in Astronomy and Astrophysics

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

Studying the accretion process in very low-mass objects has important implications for understanding their formation mechanism. Many nearby late-M dwarfs that have previously been identified in the field are in fact young brown dwarf members of nearby young associations. Some of them are still accreting. They are therefore excellent targets for further studies of the accretion process in the very low-mass regime at different stages.
We aim to search for accreting young brown dwarf candidates in a sample of 85 nearby late-M dwarfs.
Using photometric data from DENIS, 2MASS, and WISE, we constructed the spectral energy distribution of the late-M dwarfs based on BT-Settl models to detect infrared excesses. We then searched for lithium and H$\alpha$ emission in candidates that exhibit infrared excesses to confirm their youth and the presence of accretion.
Among the 85 late-M dwarfs, only DENIS-P J1538317$-$103850 (M5.5) shows strong infrared excesses in WISE bands. The detection of lithium absorption in the M5.5 dwarf and its Gaia trigonometric parallax indicate an age of $\sim$1 Myr and a mass of 47 $M_{\rm J}$. The H$\alpha$ emission line in the brown dwarf shows significant variability that indicates sporadic accretion. This 1 Myr-old brown dwarf also exhibits intense accretion bursts with accretion rates of up to $10^{-7.9}$$M_{\odot}$ yr$^{-1}$.
Our detection of sporadic accretion in one of the youngest brown dwarfs might imply that sporadic accretion at early stages could play an important role in the formation of brown dwarfs. Very low-mass cores would not be able to accrete enough material to become stars, and thus they end up as brown dwarfs.

[28]  arXiv:2001.08892 [pdf, ps, other]

Title: Variable stars in the Sh 2-170 HII region

Authors: Tirthendu Sinha, Saurabh Sharma, A. K. Pandey, R. K. Yadav, K. Ogura, N. Matsunaga, N. Kobayashi, P. S. Bisht, R. Pandey, A. Ghosh

Comments: Accepted for publication in MNRAS, 22 pages, 23 figures, 5 tables

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

We present multi-epoch deep ($\sim$20 mag) $I_{c}$~band photometric monitoring of the Sh 2-170 star-forming region to understand the variability properties of pre-main-sequence (PMS) stars. We report identification of 47 periodic and 24 non-periodic variable stars with periods and amplitudes ranging from $\sim$4 hrs to 18 days and from $\sim$0.1 to 2.0 mag, respectively. We have further classified 49 variables as PMS stars (17 Class\,{\sc ii} and 32 Class\,{\sc iii}) and 17 as main-sequence (MS)/field star variables. A larger fraction of MS/field variables (88\%) show periodic variability as compared to the PMS variables (59\%). The ages and masses of the PMS variable stars are found to be comparable with those of T-Tauri stars. Their variability amplitudes show an increasing trend with the near-IR/mid-IR excess. The period distribution of the PMS variables shows two peaks, one near $\sim$1.5 days and the other near $\sim$4.5 days. It is found that the younger stars with thicker discs and envelopes seem to rotate slower than their older counterparts. These properties of the PMS variables support the disc-locking mechanism. Both the period and amplitude of PMS stars show decrease with increasing mass probably due to the effective dispersal of circumstellar discs in massive stars. Our results favour the notion that cool spots on weak line T-Tauri stars are responsible for most of their variations, while hot spots on classical T-Tauri stars resulting from variable mass accretion from an inner disc contribute to their larger amplitudes and irregular behaviours.

[29]  arXiv:2001.08897 [pdf, ps, other]

Title: On the Injection of Relativistic Electrons in the Jet of 3C 279

Authors: Wen Hu, Dahai Yan, Benzhong Dai, Wei Zeng, Qianglin Hu

Comments: 18 pages, 12 figures, 3 tables, accepted for publication in MNRAS

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

The acceleration of electrons in 3C 279 is investigated through analyzing the injected electron energy distribution (EED) in a time-dependent synchrotron self-Compton + external Compton emission model. In this model, it is assumed that relativistic electrons are continuously injected into the emission region, and the injected EED [$Q_e^\prime(\gamma^\prime)$] follows a single power-law form with low- and high-energy cutoffs $\rm \gamma_{min}'$ and $\rm \gamma_{max}'$, respectively, and the spectral index $n$, i.e, $Q_e^\prime(\gamma^\prime)\propto\gamma^{\prime-n}$. This model is applied to 14 quasi-simultaneous spectral energy distributions (SEDs) of 3C 279. The Markov Chain Monte Carlo fitting technique is performed to obtain the best-fitting parameters and the uncertainties on the parameters. The results show that the injected EED is well constrained in each state. The value of $n$ is in the range of 2.5 to 3.8, which is larger than that expected by the classic non-relativistic shock acceleration. However, the large value of $n$ can be explained by the relativistic oblique shock acceleration. The flaring activity seems to be related to an increased acceleration efficiency, reflected in an increased $\gamma'_{\rm min}$ and electron injection power.

[30]  arXiv:2001.08900 [pdf, ps, other]

Title: The relationship between X-ray and optical absorbers in active galactic nuclei

Authors: Gunnar W. Jaffarian, C. Martin Gaskell

Comments: 11 pages, 4 figures. Accepted for publication in Monthly Notices of the Royal Astronomical Society

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

We present a large compilation of reddening estimates from broad-line Balmer decrements for active galactic nuclei (AGNs) with measured X-ray column densities. The median reddening is E(B-V) ~ 0.77 +/- 0.10 for type-1 to type-1.9 AGNs with reported column densities. This is notably higher than the median reddening of AGNs from the SDSS. We attribute this to the selection bias of the SDSS towards blue AGNs. For other AGNs we find evidence of a publication bias against reporting low column densities. We find a significant correlation between N_H and E(B-V) but with a large scatter of +/- 1 dex (without accounting for uncertainties in measurements). On average the X-ray columns are consistent with those predicted from E(B-V) for a solar neighbourhood dust-to-gas ratio. We argue that the large scatter of column densities and reddenings can be explained by X-ray column-density variability. For AGNs with detectable broad-line regions (BLRs) that have undergone significant changes of Seyfert type (changing-look AGNs) we do not find any statistically significant differences in N_H or E(B-V) compared to standard type-1 to type-1.9 AGNs. There is no evidence for any type-1 AGNs being Compton-thick. We also analyze type-2 AGNs and find no significant correlation between N_H and narrow-line region reddening. The median column density of LINERs is 22.68 +/- 0.75 compared to a column density of 22.90 +/- 0.28 for type-2s. We find the majority of low column density type-2s are LINERs, but N_H is probably underestimated because of scattered X-ray light diluting the photoelectric edge.

[31]  arXiv:2001.08920 [pdf, other]

Title: G279.0+1.1: a new extended source of high-energy gamma rays

Authors: Miguel Araya

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

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

G279.0+1.1 is a supernova remnant (SNR) with poorly known parameters, first detected as a dim radio source and classified as an evolved system. An analysis of data from the Fermi-LAT revealing for the first time an extended source of gamma rays in the region is presented. The diameter of the GeV region found is ~2.8$^{\circ}$, larger than the latest estimate of the SNR size from radio data. The gamma-ray emission covers most of the known shell and extends further to the north and east of the bulk of the radio emission. The photon spectrum in the 0.5--500 GeV range can be described by a simple power law, $\frac{dN}{dE} \propto E^{-\Gamma}$, with a spectral index of $\Gamma = 1.86\pm 0.03_{stat} \pm 0.06_{sys}$. In the leptonic scenario, a steep particle spectrum is required and a distance lower than the previously estimated value of 3 kpc is favored. The possibility that the high-energy emission results from electrons that already escaped the SNR is also investigated. A hadronic scenario for the gamma rays yields a particle spectral index of $\sim2.0$ and no significant constraints on the distance. The production of gamma rays in old SNRs is discussed. More observations of this source are encouraged to probe the true extent of the shell and its age.

[32]  arXiv:2001.08946 [pdf, other]

Title: Effect of vegetation on the temperatures of Trappist-1 planets

Authors: Antonio Vecchio, Leonardo Primavera, Fabio Lepreti, Tommaso Alberti, Vincenzo Carbone

Comments: 11 pages, 6 figures, 2 tables, accepted for publication in ApJ

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

TRAPPIST-1 is an ultra-cool dwarf hosting a system consisting of seven planets. While orbital properties, radii and masses of the planets are nowadays well constrained, one of the open fascinating issues is the possibility that an environment hospitable to life could develop on some of these planets. Here we use a simple formulation of an energy balance model that includes the vegetation coverage to investigate the possibility of life affecting the climate of the planets in the TRAPPIST-1 system. Results confirm that planet T-e has the best chance for a habitable world and indicate that vegetation coverage significantly affects the resulting temperatures and habitability properties. The influence of vegetation has been evaluated in different scenarios characterized by different vegetation types, land-sea distributions and levels of greenhouse effect. While changes in vegetation type produce small changes, about $0.1\%$, in the habitable surface fraction, different land-sea distributions, by also affecting the vegetation growth, produce different temperature distributions. Finally at latitudes where vegetation grows, the lowering of local albedo still represents a relevant contribution in settling the planetary temperature profiles even when levels of greenhouse effect higher than the Earth-like case are considered.

[33]  arXiv:2001.08951 [pdf, other]

Title: A universal formula for the relativistic correction to the mutual friction coupling time-scale in neutron stars

Authors: Lorenzo Gavassino, Marco Antonelli, Pierre Pizzochero, Brynmor Haskell

Comments: Submitted to MNRAS

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

Vortex mediated mutual friction governs the coupling between the superfluid and normal components in neutron star interiors. By, for example, comparing precise timing observations of pulsar glitches with theoretical predictions it is possible to constrain the physics in the interior of the star, but to do so an accurate model of the mutual friction coupling in General Relativity is needed. We derive such a model directly from Carter's multi-fluid formalism, and study the vortex structure and coupling timescale between the components in a relativistic star. We calculate how General Relativity modifies the shape and the density of the quantised vortices and show that, in the quasi-Schwarzschild coordinates, they can be approximated as straight lines for realistic neutron star configurations. Finally, we present a simple universal formula (given as a function of the stellar compactness alone) for the relativistic correction to the glitch rise-time, which is valid under the assumption that the superfluid reservoir is in a thin shell in the crust or in the outer core. This universal relation can be easily employed to correct, a posteriori, any Newtonian estimate for the coupling time scale, without any additional computational expense.

[34]  arXiv:2001.08964 [pdf, other]

Title: Force on a neutron quantised vortex pinned to proton fluxoids in the superfluid core of cold neutron stars

Authors: Aurélien Sourie, Nicolas Chamel

Comments: 8 pages, 2 figures. Accepted for publication in MNRAS

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

The superfluid and superconducting core of a cold rotating neutron star is expected to be threaded by a tremendous number of neutron quantised vortices and proton fluxoids. Their interactions are unavoidable and may have important astrophysical implications. In this paper, the various contributions to the force acting on a single vortex to which fluxoids are pinned are clarified. The general expression of the force is derived by applying the variational multifluid formalism developed by Carter and collaborators. Pinning to fluxoids leads to an additional Magnus type force due to proton circulation around the vortex. Pinning in the core of a neutron star may thus have a dramatic impact on the vortex dynamics, and therefore on the magneto-rotational evolution of the star.

[35]  arXiv:2001.08969 [pdf, other]

Title: Physical properties of Taurid meteoroids of various sizes

Authors: Jiri Borovicka, Pavel Spurny

Comments: Accepted to Planetary and Space Science. 22 pages, 16 figures, 1 table. License CC-BY-NC-ND (required by the journal)

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

The origin of the Taurid complex is still debated. In addition to comet 2P/Encke, various asteroids were proposed to be members of the complex and thus possible parent bodies of Taurid meteoroids. Studies of physical properties of Taurid meteoroids can provide constrains on their source. We used a well defined orbital sample of 16 Taurid fireballs with detailed radiometric light curves. The sample represented meteoroids of initial masses from 8 grams to 650 kg (diameters 1 - 70 cm). The semi-empirical fragmentation model was used to study their atmospheric fragmentation and derive strength distribution within the meteoroids. It was found that small meteoroids are stronger than large ones. When considering Taurid material as a whole, the majority has a very low strength of less than 0.01 MPa and a density less than 1000 kg/m3. The low strength material exists mostly as large bodies (>10 cm). If encountered in smaller bodies, it forms only a minor part. Stronger materials up to 0.3 MPa exist in Taurids as well, but the stronger material the rarer it is. Strong material forms small inclusions in large bodies or exists as small (cm-sized) separate bodies. These properties strongly suggest cometary origin of Taurids.

[36]  arXiv:2001.09057 [pdf, other]

Title: Search for correlations of high-energy neutrinos and ultra-high energy cosmic rays

Authors: A. Barbano (for the IceCube Collaboration, the Pierre Auger Collaboration, the Telescope Array Collaboration, the ANTARES Collaboration)

Comments: Presented at the 36th International Cosmic Ray Conference (ICRC 2019), 8 pages, 2 figures

Journal-ref: PoS(ICRC2019)842

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

The sources of ultra-high energy cosmic rays (UHECRs) are still one of the main open questions in high-energy astrophysics. If UHECRs are accelerated in astrophysical sources, they are expected to produce high-energy photons and neutrinos due to the interaction with the surrounding astrophysical medium or ambient radiation. In particular, neutrinos are powerful probes for the investigation of the region of production and acceleration of UHECRs since they are not sensitive to magnetic deflections nor to interactions with the interstellar medium. The results of three different analyses that correlate the very high-energy neutrino candidates detected by IceCube and ANTARES and the highest-energy cosmic rays measured by the Pierre Auger Observatory and the Telescope Array will be discussed. The first two analyses use a sample of high-energy neutrinos from IceCube and ANTARES selected to have a significant probability to be of astrophysical origin. The first analysis cross-correlates the arrival directions of these selected neutrino events and UHECRs. The second one is a stacked likelihood analysis assuming as stacked sources the high-energy neutrino directions and looking for excesses in the UHECR data set around the directions of the neutrino candidates. The third analysis instead uses a larger sample of neutrinos selected to look for neutrino point-like sources. It consists of a likelihood method that looks for excesses in the neutrino point-source data set around the directions of the highest-energy UHECRs.

[37]  arXiv:2001.09058 [pdf, other]

Title: Into the Lyα jungle: exploring the circumgalactic medium of galaxies at z ~ 4-5 with MUSE

Authors: Richard M. Bielby (CEA/IDAC, Durham), Michele Fumagalli (CEA/ICC, Durham), Matteo Fossati (CEA, Durham), Marc Rafelski, Benjamin Oppenheimer, Sebastiano Cantalupo, Lise Christensen, J. P. U. Fynbo, Sebastian Lopez, Simon L. Morris (CEA/CfAI, Durham), Valentina D'Odorico, Celine Peroux

Comments: 19 pages (+2 pages appendices), 19 figures (+4 in appendices). Submitted to MNRAS

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

We present a study of the galaxy environment of 9 strong HI+CIV absorption line systems ($16.2<{\rm log}(N({\rm HI}))<21.2$) spanning a wide range in metallicity at $z\sim4-5$, using MUSE integral field and X-Shooter spectroscopic data collected in a $z\approx 5.26$ quasar field. We identify galaxies within a 250 kpc and $\pm1000$ km s$^{-1}$ window for 6 out of the 9 absorption systems, with 2 of the absorption line systems showing multiple associated galaxies within the MUSE field of view. The space density of Ly$\alpha$ emitting galaxies (LAEs) around the HI and CIV systems is $\approx10-20$ times the average sky density of LAEs given the flux limit of our survey, showing a clear correlation between the absorption and galaxy populations. Further, we find that the strongest CIV systems in our sample are those that are most closely aligned with galaxies in velocity space, i.e. within velocities of $\pm500$ km s$^{-1}$. The two most metal poor systems lie in the most dense galaxy environments, implying we are potentially tracing gas that is infalling for the first time into star-forming groups at high redshift. Finally, we detect an extended Ly$\alpha$ nebula around the $z\approx 5.26$ quasar, which extends up to $\approx50$ kpc at the surface brightness limit of $3.8 \times 10^{-18}$ erg s$^{-1}$ cm$^{-2}$ arcsec$^{-2}$. After scaling for surface brightness dimming, we find that this nebula is centrally brighter, having a steeper radial profile than the average for nebulae studied at $z\sim3$ and is consistent with the mild redshift evolution seen from $z\approx 2$.

[38]  arXiv:2001.09073 [pdf, ps, other]

Title: The cosmic atomic hydrogen mass density as a function of mass and galaxy hierarchy from spectral stacking

Authors: Wenkai Hu, Barbara Catinella, Luca Cortese, Lister Staveley-Smith, Claudia del P. Lagos, Garima Chauhan, Tom Oosterloo, Xuelei Chen

Comments: 9 gages, 6 figures, Accepted for publication in MNRAS

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

We use spectral stacking to measure the contribution of galaxies of different masses and in different hierarchies to the cosmic atomic hydrogen (HI) mass density in the local Universe. Our sample includes 1793 galaxies at $z < 0.11$ observed with the Westerbork Synthesis Radio Telescope, for which Sloan Digital Sky Survey spectroscopy and hierarchy information are also available. We find a cosmic HI mass density of $\Omega_{\rm HI} = (3.99 \pm 0.54)\times 10^{-4} h_{70}^{-1}$ at $\langle z\rangle = 0.065$. For the central and satellite galaxies, we obtain $\Omega_{\rm HI}$ of $(3.51 \pm 0.49)\times 10^{-4} h_{70}^{-1}$ and $(0.90 \pm 0.16)\times 10^{-4} h_{70}^{-1}$, respectively. We show that galaxies above and below stellar masses of $\sim$10$^{9.3}$ M$_{\odot}$ contribute in roughly equal measure to the global value of $\Omega_{\rm HI}$. While consistent with estimates based on targeted HI surveys, our results are in tension with previous theoretical work. We show that these differences are, at least partly, due to the empirical recipe used to set the partition between atomic and molecular hydrogen in semi-analytical models. Moreover, comparing our measurements with the cosmological semi-analytic models of galaxy formation {\sc Shark} and GALFORM reveals gradual stripping of gas via ram pressure works better to fully reproduce the properties of satellite galaxies in our sample, than strangulation. Our findings highlight the power of this approach in constraining theoretical models, and confirm the non-negligible contribution of massive galaxies to the HI mass budget of the local Universe.

[39]  arXiv:2001.09083 [pdf, ps, other]

Title: Orbital Dynamics of 2020 AV2: the First Vatira Asteroid

Authors: Sarah Greenstreet

Comments: Submitted to MNRAS

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

Vatira-class near-Earth objects (NEOs) have orbits entirely interior to the orbit of Venus with aphelia $0.307<Q<0.718$ AU. Recently discovered asteroid 2020 AV2 by the Zwicky Transient Facility on 4 January 2020 is the first known object on a Vatira orbit. Numerical integrations of 2020 AV2's nominal orbit show it remaining in the Vatira region for the next few hundred kyr before coupling to Venus and evolving onto an Atira orbit (NEOs entirely interior to Earth's orbit with $0.718<Q<0.983$ AU) and eventually scattering out to Earth-crossing. The numerical integration of 9900 clones within the orbital uncertainty region of 2020 AV2 show examples of possible Vatira orbits trapped in the 3:2 mean-motion resonance with Venus at semimajor axis $a\approx0.552$ AU that can survive on the order of a few Myr. Possible 2020 AV2 orbits also include those on Vatira orbits between Mercury and Venus that only rarely cross that of a planet. Together the 3:2 resonance and these rarely-planet-crossing orbits provide a meta-stable region of phase space that are stable on timescales of several Myr. If 2020 AV2 is currently in this meta-stable region (or was in the past), that may explain its discovery as the first Vatira.

[40]  arXiv:2001.09089 [pdf, ps, other]

Title: Suppressed-gap millimetre wave kinetic inductance detectors using DC-bias current

Authors: Songyuan Zhao, Stafford Withington, David J. Goldie, Chris N. Thomas

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

In this study, we evaluate the suitability of using DC-biased aluminium resonators as low-frequency kinetic inductance detectors capable of operating in the frequency range of 50 - 120 GHz. Our analysis routine for supercurrent-biased resonators is based on the Usadel equations and gives outputs including density of states, complex conductivities, transmission line properties, and quasiparticle lifetimes. Results from our analysis confirm previous experimental observations on resonant frequency tuneability and retention of high quality factor. Crucially, our analysis suggests that DC-biased resonators demonstrate significantly suppressed superconducting density of states gap. Consequently these resonators have lower frequency detection threshold and are suitable materials for low-frequency kinetic inductance detectors.

[41]  arXiv:2001.09095 [pdf, other]

Title: Peculiar velocity cosmology with type Ia supernovae

Authors: R. Graziani, M. Rigault, N. Regnault, Ph. Gris, A. Möller, P. Antilogus, P. Astier, M. Betoule, S. Bongard, M. Briday, J. Cohen-Tanugi, Y. Copin, H. M. Courtois, D. Fouchez, E.Gangler, D. Guinet, A. J. Hawken, Y.-L. Kim, P.-F. Léget, J. Neveu, P. Ntelis, Ph. Rosnet, E. Nuss

Comments: White paper CNRS/IN2P3 Prospectives 2020

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

Type Ia Supernovae have yet again the opportunity to revolutionize the field of cosmology as the new generation of surveys are acquiring thousands of nearby SNeIa opening a new era in cosmology: the direct measurement of the growth of structure parametrized by $fD$. This method is based on the SNeIa peculiar velocities derived from the residual to the Hubble law as direct tracers of the full gravitational potential caused by large scale structure. With this technique, we could probe not only the properties of dark energy, but also the laws of gravity. In this paper we present the analytical framework and forecasts. We show that ZTF and LSST will be able to reach 5\% precision on $fD$ by 2027. Our analysis is not significantly sensitive to photo-typing, but known selection functions and spectroscopic redshifts are mandatory. We finally introduce an idea of a dedicated spectrograph that would get all the required information in addition to boost the efficiency to each SNeIa so that we could reach the 5\% precision within the first two years of LSST operation and the few percent level by the end of the survey.

[42]  arXiv:2001.09101 [pdf, ps, other]

Title: Validating the Universe in a Box

Authors: Chris Smeenk, Sarah C. Gallagher

Comments: 13 pages. Accepted for publication in Philosophy of Science for the PSA2018 symposium proceedings issue

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

Computer simulations of the formation and evolution of large scale structure in the universe are integral to the enterprise of modern cosmology. Establishing the reliability of these simulations has been extremely challenging, primarily because of epistemic opacity. In this setting, robustness analysis defined by requiring converging outputs from a diverse ensemble of simulations is insufficient to determine simulation validity. Instead, we propose an alternative path of structured code validation that applies eliminative reasoning to isolate and reduce possible sources of error, a potential path that is already being explored by some cosmologists.

[43]  arXiv:2001.09110 [pdf, ps, other]

Title: A multi-wavelength study of spiral structure in galaxies. I. General characteristics in the optical

Authors: Sergey Savchenko, Alexander Marchuk, Aleksandr Mosenkov, Konstantin Grishunin

Comments: 20 pages, 23 figures. Accepted for publication in MNRAS

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

Different spiral generation mechanisms are expected to produce different morphological and kinematic features. In this first paper in a series we carefully study the parameters of spiral structure in 155 face-on spiral galaxies, selected from the Sloan Digital Sky Survey, in the three $gri$ bands. We use a method for deriving a set of parameters of spiral structure, such as the width of the spiral arms, their fraction to the total galaxy luminosity and their colour, which have not been properly studied before. Our method is based on an analysis of a set of photometric cuts perpendicular to the direction of a spiral arm. Based on the results of our study, we compare the main three classes of spirals: grand design, multi-armed and flocculent. We conclude that: i) for the vast majority of galaxies (86\%) we observe an increase of their arm width with galactocentric distance; ii) more luminous spirals in grand design galaxies exhibit smaller variations of the pitch angle with radius than less luminous grand design spirals; iii) grand design galaxies show less difference between the pitch angles of individual arms than multi-armed galaxies. Apart from these distinctive features, all three spiral classes do not differ significantly by their pitch angle, arm width, width asymmetry, and environment. Wavelength dependence is found only for the arm fraction. Therefore, observationally we find no strong difference (except for the view and number of arms) between grand design, multi-armed and flocculent spirals in the sample galaxies.

[44]  arXiv:2001.09129 [pdf, other]

Title: Distinguishing freezing and thawing dark energy models through measurements of the fine-structure constant

Authors: J. M. A. Vilas Boas, D. M. N. Magano, C. J. A. P. Martins, A. Barbecho, C. Serrano

Comments: 12 pages, 9 figures, 4 tables; A & A (in press)

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

Mapping the behaviour of dark energy is a pressing task for observational cosmology. Phenomenological classification divides dynamical dark energy models into freezing and thawing, depending on whether the dark energy equation of state is approaching or moving away from $w=p/\rho=-1$. Moreover, in realistic dynamical dark energy models the dynamical degree of freedom is expected to couple to the electromagnetic sector, leading to variations of the fine-structure constant $\alpha$. We discuss the feasibility of distinguishing between the freezing and thawing classes of models with current and forthcoming observational facilities and using a parametrisation of the dark energy equation of state, which can have either behaviour, introduced by Mukhanov as fiducial paradigm. We illustrate how freezing and thawing models lead to different redshift dependencies of $\alpha$, and use a combination of current astrophysical observations and local experiments to constrain this class of models, improving the constraints on the key coupling parameter by more than a factor of two, despite considering a more extended parameter space than the one used in previous studies. We also briefly discuss the improvements expected from future facilities and comment on the practical limitations of this class of parametrisations. In particular, we show that sufficiently sensitive data can distinguish between freezing and thawing models, at least if one assumes that the relevant parameter space does not include phantom dark energy models.

[45]  arXiv:2001.09142 [pdf, ps, other]

Title: Reflex motion in the Milky Way stellar halo resulting from the Large Magellanic Cloud infall

Authors: Michael S. Petersen, Jorge Peñarrubia

Comments: Submitted to MNRAS, comments welcome

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

We present the results of N-body models of the Milky Way and Large Magellanic Cloud system and study the kinematic reflex motion in the stellar halo owing to the barycentre displacement of the disc. In agreement with previous studies, we find that the Milky Way disc may be moving at 40 km/s relative to the barycentre prior to the Large Magellanic Cloud infall. The resulting reflex motion is visible in tangential velocities of the stellar halo as a simple dipole. The signal is strongest for stars with long dynamical times, identifiable in position-velocity data as stars with large apocentres, whose dynamical memory is still well-represented by the unperturbed Milky Way potential. The signal varies across the sky depending on the stellar tracer and may be up to the same magnitude as the velocity of the disc centre-of-mass, making reflex motion a source of bias for Milky Way potential determinations based on the modeling of stellar streams and/or smooth halo tracers such as blue horizontal branch or RR Lyrae stars.

[46]  arXiv:2001.09150 [pdf]

Title: The Orbit of Planet Nine Derived from Engineering Physics

Authors: Robert Finch, Mattia A. Galiazzo

Comments: 15 pages, 2 figures

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

Several papers have recently suggested the possible presence of a ninth planet (Planet X) that might explain the gravitational perturbations of a number of detached Trans-Neptunian objects. To analyze the possibility further, we have applied celestial mechanics, engineering physics and statistical analysis to develop improved estimates of the planet's primary orbital elements and mass from first engineering principles, using the orbital characteristics of both the original group of 6 objects analyzed and also a second group comprising the original 6 together with 6 additional long-period asteroids selected by the authors. We show that the driving force behind the observed clustering is gravitational torque that arranges the orbits of asteroids in a systematic, orderly manner, and we develop the associated equations of motion. As evidence we show that the expected effects are fully apparent in the orbital characteristics of the correlated bodies involved, including most strikingly regarding their orbital planes, azimuth orientations and specific relative angular momenta, which we show generates a highly unexpected form of resonance in their relative angular momenta. We further show that the coordinates of Planet 9's orbit are close to the original values proposed recently by other authors, although we prove that its period has to be dramatically smaller than that proposed in recent literature by Batygin and Brown, 2019, at about 3500 yrs, the eccentricity is near 0.65, and its mass approximately 8.4 times the Earth's mass. Given the predicted orbit we show that the planet has apparently created numerous mean motion resonances, of which seven are noted specifically. As for a possible observation, Planet X, would range between V=18.9 and 26.1, probably with a magnitude of about 24.8.

Cross-lists for Mon, 27 Jan 20

[47]  arXiv:2001.08750 (cross-list from gr-qc) [pdf, other]

Title: Universal Polarimetric Signatures of the Black Hole Photon Ring

Authors: Elizabeth Himwich, Michael D. Johnson, Alexandru Lupsasca, Andrew Strominger

Comments: 13 pages, 4 figures

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

Black hole images present an annular region of enhanced brightness. In the absence of propagation effects, this "photon ring" has universal features that are completely governed by general relativity and independent of the details of the emission. Here, we show that the polarimetric image of a black hole also displays universal properties. In particular, the photon ring exhibits a self-similar pattern of polarization that encodes the black hole spin. We explore the corresponding universal polarimetric signatures of the photon ring on long interferometric baselines, and propose a method for measuring the black hole spin using a sparse interferometric array. These signatures could enable spin measurements of the supermassive black hole in M87, as well as precision tests of general relativity in the strong field regime, via a future extension of the Event Horizon Telescope to space.

[48]  arXiv:2001.08833 (cross-list from gr-qc) [pdf, other]

Title: Black Hole evaporation: A Perspective from Loop Quantum Gravity

Authors: Abhay Ashtekar

Comments: 25 pages, 8 Figures. Invited article for a special issue "Probing New Physics with Black Holes", edited by Aurelien Barrau

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

A personal perspective on the black hole evaporation process is presented using as guidelines inputs from: (i) loop quantum gravity, (ii) simplified models where concrete results have been obtained, and, (iii) semi-classical quantum general relativity. On the one hand, the final picture is conservative in that there are concrete results that support each stage of the argument, and there are no large departures from general relativity or semi-classical gravity in tame regions outside macroscopic black holes. On the other hand it argues against certain views that are commonly held in many quarters, such as: persistence of a piece of singularity that constitutes a part of the final boundary of space-time; presence of an \emph{event} horizon serving as an absolute barrier between the interior and the exterior; and the (often implicit) requirement that purification must be completed by the time the `last rays' representing the extension of this event horizon reach $\mathcal{I}^{+}$.

[49]  arXiv:2001.08910 (cross-list from hep-ph) [pdf, other]

Title: Projected sensitivity to sub-GeV dark matter of next-generation semiconductor detectors

Authors: Erik Andersson, Alex Bökmark, Riccardo Catena, Timon Emken, Henrik Klein Moberg, Emil Åstrand

Comments: 17 pages, 4 figures

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

We compute the projected sensitivity to dark matter (DM) particles in the sub-GeV mass range of future direct detection experiments using germanium and silicon semiconductor targets. We perform this calculation within the dark photon model for DM-electron interactions using the likelihood ratio as a test statistic, Monte Carlo simulations, and background models that we extract from recent experimental data. We present our results in terms of DM-electron scattering cross section values required to reject the background only hypothesis in favour of the background plus DM signal hypothesis with a statistical significance, $\mathcal{Z}$, corresponding to 3 or 5 standard deviations. We also test the stability of our conclusions under changes in the astrophysical parameters governing the local space and velocity distribution of DM in the Milky Way. In the best-case scenario, when a high-voltage germanium detector with an exposure of $50$ kg-year and a CCD silicon detector with an exposure of $1$ kg-year and a dark current rate of $1\times10^{-7}$ counts/pixel/day have simultaneously reported a DM signal, we find that the smallest cross section value compatible with $\mathcal{Z}=3$ ($\mathcal{Z}=5$) is about $8\times10^{-42}$ cm$^2$ ($1\times10^{-41}$ cm$^2$) for contact interactions, and $4\times10^{-41}$ cm$^2$ ($7\times10^{-41}$ cm$^2$) for long-range interactions. Our sensitivity study extends and refine previous works in terms of background models, statistical methods, and treatment of the underlying astrophysical uncertainties.

[50]  arXiv:2001.08947 (cross-list from physics.ins-det) [pdf, other]

Title: First Characterization of a Superconducting Filter-bank Spectrometer for Hyper-spectral Microwave Atmospheric Sounding with Transition Edge Sensors

Authors: D. J. Goldie, C. N. Thomas, S. Withington, A. Orlando, R. Sudiwala, P. Hargrave, P. K. Dongre

Comments: 13 pages, 12 figures

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

We describe the design, fabrication, integration and characterization of a prototype superconducting filter bank with transition edge sensor readout designed to explore millimetre-wave detection at frequencies in the range 40 to 65 GHz. Results indicate highly uniform filter channel placement in frequency and high overall detection efficiency. The route to a full atmospheric sounding instrument in this frequency range is discussed.

[51]  arXiv:2001.09088 (cross-list from hep-th) [pdf, other]

Title: Standard Model Meets Gravity: Electroweak Symmetry Breaking and Inflation

Authors: Mikhail Shaposhnikov, Andrey Shkerin, Sebastian Zell

Comments: 6 pages, 1 figure

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

We propose a model for combining the Standard Model (SM) with gravity. It relies on a non-minimal coupling of the Higgs field to the Ricci scalar and on the Palatini formulation of gravity. Without introducing any new degrees of freedom in addition to those of the SM and the graviton, this scenario achieves two goals. First, it generates the electroweak symmetry breaking by a non-perturbative gravitational effect. In this way, it does not only address the hierarchy problem but opens up the possibility to calculate the Higgs mass. Second, the model incorporates inflation at energies below the onset of strong-coupling of the theory. Provided that corrections due to new physics above the scale of inflation are not unnaturally large, we can relate inflationary parameters to data from collider experiments.

[52]  arXiv:2001.09117 (cross-list from gr-qc) [pdf, ps, other]

Title: Ultra long lived quasinormal modes of neutron stars in $R^2$ gravity

Authors: Jose Luis Blázquez-Salcedo, Fech Scen Khoo, Jutta Kunz

Comments: 6 pages, 3 figures

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

The spectrum of frequencies and characteristic times that compose the ringdown phase of gravitational waves emitted by neutron stars carry information about the matter content (the equation of state) and the underlying theory of gravity. Typically, modified theories of gravity introduce additional degrees of freedom/fields, such as scalars, which result in new families of modes composing the ringdown spectrum. One simple but physically promising candidate is $R^2$ gravity, which effectively introduces an additional massive scalar field that couples non-minimally to gravity, resulting in scalarized neutron stars. Here we show that the ringdown spectrum of $R^2$ neutron stars is much richer and fundamentally different from the spectrum in GR, possessing for instance ultra long lived modes that can propagate away from the star in the form of scalar gravitational radiation.

[53]  arXiv:2001.09140 (cross-list from hep-ph) [pdf, other]

Title: Heating neutron stars with GeV dark matter

Authors: Wai-Yee Keung, Danny Marfatia, Po-Yan Tseng

Comments: 24 pages, 12 figures

Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR); High Energy Physics - Experiment (hep-ex)

An old neutron star (NS) may capture halo dark matter (DM) and get heated up by the deposited kinetic energy, thus behaving like a thermal DM detector with sensitivity to a wide range of DM masses and a variety of DM-quark interactions. Near future infrared telescopes will measure NS temperatures down to a few thousand Kelvin and probe NS heating by DM capture. We focus on GeV-mass Dirac fermion DM (which is beyond the reach of current DM direct detection experiments) in scenarios in which the DM capture rate can saturate the geometric limit. For concreteness, we study (1) a model that invokes dark decays of the neutron to explain the neutron lifetime anomaly, and (2) a framework of DM coupled to quarks through a vector current portal. In the neutron dark decay model a NS can have a substantial DM population, so that the DM capture rate can reach the geometric limit through DM self-interactions even if the DM-neutron scattering cross section is tiny. We find NS heating to have greater sensitivity than multi-pion signatures in large underground detectors for the neutron dark decay model, and sub-GeV gamma-ray signatures for the quark vector portal model.

[54]  arXiv:2001.09149 (cross-list from hep-th) [pdf, other]

Title: Signals of a Quantum Universe

Authors: Daniel Green, Rafael A. Porto

Comments: 17 pages. 2 figures

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

Structure in the Universe is widely believed to have originated from quantum fluctuations during an early epoch of accelerated expansion. Yet, the patterns we observe today do not distinguish between quantum or classical primordial fluctuations; current cosmological data is consistent with either possibility. We argue here that a detection of primordial non-Gaussianity can resolve the present situation, and provide a litmus-test for the quantum origin of cosmic structure. Unlike in quantum mechanics, vacuum fluctuations cannot arise in classical theories and therefore long-range classical correlations must result from (real) particles in the initial state. Similarly to flat-space scattering processes, we show how basic principles require these particles to manifest themselves as poles in the $n$-point functions, in the so-called folded configurations. Following this observation, and assuming fluctuations are (i) correlated over large scales, and (ii) generated by local evolution during an inflationary phase, we demonstrate that: the absence of a pole in the folded limit of non-Gaussian correlators uniquely identifies the quantum vacuum as the initial state. In the same spirit as Bell's inequalities, we discuss how this can be circumvented if locality is abandoned. We also briefly discuss the implications for simulations of a non-Gaussian universe.

Replacements for Mon, 27 Jan 20

[55]  arXiv:1701.00603 (replaced) [pdf, other]

Title: Gravitational Instabilities of the Cosmic Neutrino Background with Non-zero Lepton Number

Authors: Neil D. Barrie, Archil Kobakhidze

Comments: 12 pages, 1 figure, updated to match PLB

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

[56]  arXiv:1701.08422 (replaced) [pdf]

Title: Post-Detection SETI Protocols & METI: The Time Has Come To Regulate Them Both

Authors: John Gertz

Comments: 20 pages, 0 figures, Published in JBIS Vol. 69 No. 8 August 2016

Journal-ref: JBIS Vol. 69 No. 8 August 2016

Subjects: Popular Physics (physics.pop-ph); Earth and Planetary Astrophysics (astro-ph.EP)

[57]  arXiv:1801.07778 (replaced) [pdf, other]

Title: Challenges in Scientific Data Communication from Low-Mass Interstellar Probe

Authors: David Messerschmitt, Philip Lubin, Ian Morrison

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

[58]  arXiv:1805.01421 (replaced) [pdf]

Title: Concerns about Modelling of the EDGES Data

Authors: Richard Hills, Girish Kulkarni, P. Daniel Meerburg, Ewald Puchwein

Comments: 6 pages, 2 figures; Accepted version of article published December 19, 2018. Full edited version (incl. supplementary information) available through Springer Nature at this https URL

Journal-ref: Nature 564, E32-E34 (2018)

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

[59]  arXiv:1811.09630 (replaced) [pdf, other]

Title: FLaREON : a fast computation of Ly$α$ escape fractions and line profiles

Authors: Siddhartha Gurung-Lopez, Alvaro A. Orsi, Silvia Bonoli

Comments: 7 pages, 5 figures

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

[60]  arXiv:1901.07040 (replaced) [pdf, other]

Title: Statistical Characterization of Hot Jupiter Atmospheres using Spitzer's Secondary Eclipses

Authors: Emily Garhart, Drake Deming, Avi Mandell, Heather A. Knutson, Nicole Wallack, Adam Burrows, Jonathan J. Fortney, Callie Hood, Christopher Seay, David K. Sing, Bjorn Benneke, Jonathan D. Fraine, Tiffany Kataria, Nikole Lewis, Nikku Madhusudhan, Peter McCullough, Kevin B. Stevenson, Hannah Wakeford

Comments: accepted for publication in AJ

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

[61]  arXiv:1904.04274 (replaced) [pdf, other]

Title: Lyman-alpha emitters in a cosmological volume II: the impact of the intergalactic medium

Authors: S. Gurung-Lopez, Alvaro A. Orsi, Silvia Bonoli, Nelson Padilla, Cedric G. Lacey, Carlton M. Baugh

Comments: 25 pages, 18 figures , a lot of love

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

[62]  arXiv:1906.01846 (replaced) [pdf, other]

Title: Brighter-fatter effect in near-infrared detectors -- I. Theory of flat auto-correlations

Authors: Christopher M. Hirata, Ami Choi

Comments: 45 pages, 4 figures, 1 table, version accepted by PASP, abstract abridged

Journal-ref: Publications of the Astronomical Society of the Pacific, Volume 132, Issue 1007, pp. 014501 (2020)

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

[63]  arXiv:1906.01847 (replaced) [pdf, other]

Title: Brighter-fatter effect in near-infrared detectors -- II. Auto-correlation analysis of H4RG-10 flats

Authors: Ami Choi, Christopher M. Hirata

Comments: 28 pages, 8 figures, 3 tables, version accepted by PASP

Journal-ref: Publications of the Astronomical Society of the Pacific, Volume 132, Issue 1007, pp. 014502 (2020)

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

[64]  arXiv:1906.08000 (replaced) [pdf, other]

Title: Search for intermediate mass black hole binaries in the first and second observing runs of the Advanced LIGO and Virgo network

Authors: The LIGO Scientific Collaboration, the Virgo Collaboration: B. P. Abbott, R. Abbott, T. D. Abbott, S. Abraham, F. Acernese, K. Ackley, A. Adams, C. Adams, R. X. Adhikari, V. B. Adya, C. Affeldt, M. Agathos, K. Agatsuma, N. Aggarwal, O. D. Aguiar, L. Aiello, A. Ain, P. Ajith, G. Allen, A. Allocca, M. A. Aloy, P. A. Altin, A. Amato, S. Anand, A. Ananyeva, S. B. Anderson, W. G. Anderson, S. V. Angelova, S. Antier, S. Appert, K. Arai, M. C. Araya, J. S. Areeda, M. Arène, N. Arnaud, S. M. Aronson, K. G. Arun, S. Ascenzi, G. Ashton, S. M. Aston, P. Astone, F. Aubin, P. Aufmuth, K. AultONeal, C. Austin, V. Avendano, A. Avila-Alvarez, S. Babak, P. Bacon, F. Badaracco, M. K. M. Bader, S. Bae, A. M. Baer, J. Baird, P. T. Baker, F. Baldaccini, G. Ballardin, S. W. Ballmer, A. Bals, S. Banagiri, et al. (1137 additional authors not shown)

Comments: main paper: 14 pages, 2 figures and 1 table : total with appendices 19 pages, 2 figures and 2 tables

Journal-ref: Phys. Rev. D 100, 064064 (2019)

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

[65]  arXiv:1906.12257 (replaced) [pdf, other]

Title: The origin of spin in binary black holes: Predicting the distributions of the main observables of Advanced LIGO

Authors: Simone S. Bavera, Tassos Fragos, Ying Qin, Emmanouil Zapartas, Coenraad J. Neijssel, Ilya Mandel, Aldo Batta, Sebastian M. Gaebel, Chase Kimball, Simon Stevenson

Comments: Accepted for publication in A&A on January 21th 2020, 19 pages, 9 figures

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

[66]  arXiv:1908.02779 (replaced) [pdf, other]

Title: Zee-Burst: A New Probe of Neutrino Non-Standard Interactions at IceCube

Authors: K. S. Babu, P. S. Bhupal Dev, Sudip Jana, Yicong Sui

Comments: 7 pages, 2 figures; minor changes and added references, version to appear in Phys. Rev. Lett

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

[67]  arXiv:1909.04155 (replaced) [pdf, ps, other]

Title: Magneto-electro-statics of axionically active systems: Induced field restructuring in magnetic stars

Authors: Alexander B. Balakin, Dmitry E. Groshev

Comments: 13 pages, 4 figures; replaced with the revised version published in Phys.Rev.D

Journal-ref: Phys. Rev. D 101, 023009 (2020)

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

[68]  arXiv:1909.08014 (replaced) [pdf, other]

Title: What is the amplitude of the Gravitational Waves background expected in the Starobinsky model ?

Authors: Fabrizio Renzi, Mehdi Shokri, Alessandro Melchiorri

Comments: Edited to match PDU published version

Journal-ref: Phys.Dark Univ. 27 (2020) 100450

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

[69]  arXiv:1909.09475 (replaced) [pdf, other]

Title: Axion Quark Nuggets and how a Global Network can discover them

Authors: Dmitry Budker, Victor V. Flambaum, Xunyu Liang, Ariel Zhitnitsky

Comments: Matches the published version in Phys. Rev. D

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

[70]  arXiv:1909.10605 (replaced) [pdf, other]

Title: Fermi and Swift Observations of GRB 190114C: Tracing the Evolution of High-Energy Emission from Prompt to Afterglow

Authors: M. Ajello, M. Arimoto, M. Axelsson, L. Baldini, G. Barbiellini, D. Bastieri, R. Bellazzini, A. Berretta, E. Bissaldi, R. D. Blandford, R. Bonino, E. Bottacini, J. Bregeon, P. Bruel, R. Buehler, E. Burns, S. Buson, R. A. Cameron, R. Caputo, P. A. Caraveo, E. Cavazzuti, S. Chen, G. Chiaro, S. Ciprini, J. Cohen-Tanugi, D. Costantin, S. Cutini, F. D'Ammando, M. DeKlotz, P. de la Torre Luque, F. de Palma, A. Desai, N. Di Lalla, L. Di Venere, F. Fana Dirirsa, S. J. Fegan, A. Franckowiak, Y. Fukazawa, S. Funk, P. Fusco, F. Gargano, D. Gasparrini, N. Giglietto, R. Gill, F. Giordano, M. Giroletti, J. Granot, D. Green, I. A. Grenier, M. H. Grondin, S. Guiriec, E. Hays, D. Horan, G. Jóhannesson, D. Kocevski, M. Kovac'evic', M. Kuss, S. Larsson, L. Latronico, M. Lemoine-Goumard, J. Li, et al. (89 additional authors not shown)

Comments: 24 pages, 9 figures, Accepted to ApJ

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

[71]  arXiv:1910.01127 (replaced) [pdf, other]

Title: On the Impact of Neutrino Decays on the Supernova Neutronization-Burst Flux

Authors: André de Gouvêa, Ivan Martinez-Soler, Manibrata Sen

Comments: 20 pages, 9 figures

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

[72]  arXiv:1910.01657 (replaced) [pdf, other]

Title: Gravitational Absorption Lines

Authors: Andrea Palessandro, Martin S. Sloth

Comments: 33 pages, 2 figures. Added one reference and an additional section in the appendix. Version accepted for publication in PRD

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

[73]  arXiv:1911.11831 (replaced) [pdf, other]

Title: Efficient Gravitational-wave Glitch Identification from Environmental Data Through Machine Learning

Authors: Robert E. Colgan, K. Rainer Corley, Yenson Lau, Imre Bartos, John N. Wright, Zsuzsa Marka, Szabolcs Marka

Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); General Relativity and Quantum Cosmology (gr-qc)

[74]  arXiv:1912.02862 (replaced) [pdf, other]

Title: On the Habitable Lifetime of Terrestrial Worlds with High Radionuclide Abundances

Authors: Manasvi Lingam, Abraham Loeb

Comments: 7 pages; 4 figures

Journal-ref: The Astrophysical Journal Letters, Vol. 889, L20 (2020)

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

[75]  arXiv:1912.03068 (replaced) [pdf, other]

Title: The final SDSS-IV/SPIDERS X-ray point source spectroscopic catalogue

Authors: J. Comparat, A. Merloni, T. Dwelly, M. Salvato, A. Schwope, D. Coffey, J. Wolf, R. Arcodia, T. Liu, J. Buchner, K. Nandra, A. Georgakakis, N. Clerc, M. Brusa, J. R. Brownstein, D. P. Schneider, K. Pan, D. Bizyaev

Comments: accepted in A&A Please visit our project page : this http URL The catalogs are here : this https URL and this https URL

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

[76]  arXiv:1912.07615 (replaced) [pdf, other]

Title: A systematic study of proto-neutron star convection in three-dimensional core-collapse supernova simulations

Authors: Hiroki Nagakura, Adam Burrows, David Radice, David Vartanyan

Comments: Accepted to MNRAS

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

[77]  arXiv:1912.12554 (replaced) [pdf, other]

Title: Spontaneous formation of geysers at only one pole on Enceladus' ice shell

Authors: Wanying Kang, Glenn Flierl

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

[78]  arXiv:2001.00673 (replaced) [pdf]

Title: There's No Place Like Home (in Our Own Solar System): Searching for ET Near White Dwarfs

Authors: John Gertz

Comments: Published in JBIS Vol. 72 No. 11 November 2019

Journal-ref: JBIS Vol. 72 No. 11 November 2019

Subjects: Popular Physics (physics.pop-ph); Earth and Planetary Astrophysics (astro-ph.EP)

[79]  arXiv:2001.07605 (replaced) [pdf, other]

Title: First search for r-mode gravitational waves from J0537-6910

Authors: Liudmila Fesik, Maria Alessandra Papa

Comments: 14 pages,12 figures

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

[80]  arXiv:2001.08206 (replaced) [pdf, other]

Title: Decay properties of $^{22}\mathrm{Ne} + α$ resonances and their impact on $s$-process nucleosynthesis

Authors: S. Ota, G. Christian, G. Lotay, W. N. Catford, E. A. Bennett, S. Dede, D. T. Doherty, S. Hallam, J. Hooker, C. Hunt, H. Jayatissa, A. Matta, M. Moukaddam, G. V. Rogachev, A. Saastamoinen, J. A. Tostevin, S. Upadhyayula, R. Wilkinson

Comments: 17 pages, 4 figures, accepted for publication in Phys. Lett. B

Subjects: Nuclear Experiment (nucl-ex); Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Theory (nucl-th)

[81]  arXiv:2001.08608 (replaced) [pdf, ps, other]

Title: Robustness of the pairwise kinematic Sunyaev-Zeldovich power spectrum shape as a cosmological gravity probe

Authors: Yi Zheng

Comments: 5 pages, 2 figures, we appreciate Baojiu Li and Wojciech Hellwing for providing the simulation and catalog data

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

• New submissions
• Cross-lists
• Replacements