Astrophysics

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New submissions for Wed, 12 Feb 20

[1]  arXiv:2002.04035 [pdf, other]

Title: Combining Full-Shape and BAO Analyses of Galaxy Power Spectra: A 1.6% CMB-independent constraint on H0

Authors: Oliver H.E. Philcox, Mikhail M. Ivanov, Marko Simonović, Matias Zaldarriaga

Comments: 40 pages, 11 figures, submitted to JCAP

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

We present cosmological constraints from a joint analysis of the pre- and post-reconstruction galaxy power spectrum multipoles from the final data release of the Baryon Oscillation Spectroscopic Survey (BOSS). Geometric constraints are obtained from the positions of BAO peaks in reconstructed spectra, which are analyzed in combination with the unreconstructed spectra in a full-shape (FS) likelihood using a joint covariance matrix, giving stronger parameter constraints than BAO-only or FS-only analyses. We introduce a new method for obtaining constraints from reconstructed spectra based on a correlated theoretical error, which is shown to be simple, robust, and applicable to any flavor of density-field reconstruction. Assuming $\Lambda$CDM with massive neutrinos, we analyze clustering data from two redshift bins $z_\mathrm{eff}=0.38,0.61$ and obtain $1.6\%$ constraints on the Hubble constant $H_0$, using only a single prior on the current baryon density $\omega_b$ from Big Bang Nucleosynthesis and no knowledge of the power spectrum slope $n_s$. This gives $H_0 = 68.6\pm1.1\,\mathrm{km\,s}^{-1}\mathrm{Mpc}^{-1}$, with the inclusion of BAO data sharpening the measurement by $40\%$, representing one of the strongest current constraints on $H_0$ independent of cosmic microwave background data. Restricting to the best-fit slope $n_s$ from Planck (but without additional priors on the spectral shape), we obtain a $1\%$ $H_0$ measurement of $67.8\pm 0.7\,\mathrm{km\,s}^{-1}\mathrm{Mpc}^{-1}$. Finally, we find strong constraints on the cosmological parameters from a joint analysis of the FS, BAO, and Planck data. This sets new bounds on the sum of neutrino masses $\sum m_\nu < 0.14\,\mathrm{eV}$ (at $95\%$ confidence) and the effective number of relativistic degrees of freedom $N_\mathrm{eff} = 2.90^{+0.15}_{-0.16}$, though contours are not appreciably narrowed by the inclusion of BAO data.

[2]  arXiv:2002.04037 [pdf, other]

Title: Birth, life, and death of black hole binaries around supermassive black holes: dynamical evolution of gravitational wave sources

Authors: Manuel Arca Sedda

Comments: 29 pages, 24 figures, 4 Tables, and 1 Appendix. Accepted for publication in the Astrophysical Journal

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

In this paper, we explore the mechanisms that regulate the formation and evolution of stellar black hole binaries (BHBs) around supermassive black holes (SMBHs). We show that dynamical interactions can efficiently drive "in-situ" BHB formation if the SMBH is surrounded by a massive nuclear cluster (NC), while orbitally segregated star clusters can replenish the BHB reservoir in SMBH-dominated nuclei. We discuss how the combined action of stellar hardening and mass segregation sculpts the BHB orbital properties. We use direct N-body simulations including post-Newtonian corrections up to 2.5 order to study the BHB-SMBH interplay, showing that the Kozai-Lidov mechanism plays a crucial role in shortening binaries lifetime. We find that the merging probability weakly depends on the SMBH mass in the $10^6-10^9{\rm ~M}_\odot$ mass range, leading to a merger rate $\Gamma \simeq 3-8$ yr$^{-1}$ Gpc$^{-3}$ at redshift zero. Nearly $40\%$ of the mergers have masses in the "BH mass gap", $50-140{\rm ~M}_\odot$, thus indicating that galactic nuclei are ideal places to form BHs in this mass range. We argue that gravitational wave (GW) sources with components mass $m_1>40{\rm ~M}_\odot$ and $m_2<30{\rm ~M}_\odot$ would represent a strong indicator of a galactic nuclei origin. The majority of these mergers could be multiband GW sources in the local Universe: nearly $40\%$ might be seen by LISA as eccentric sources and, a few years later, as circular sources by LIGO and the Einstein Telescope, making decihertz observatories like DECIGO unique instruments to bridge the observations during the binary inspiral.

[3]  arXiv:2002.04039 [pdf, other]

Title: Spectro-Imaging Forward Model of Red and Blue Galaxies

Authors: Martina Fagioli, Luca Tortorelli, Jörg Herbel, Dominik Zürcher, Alexandre Refregier, Adam Amara

Comments: 24 pages, 9 figures, submitted to JCAP

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

For the next generation of spectroscopic galaxy surveys, it is important to forecast their performances and to accurately interpret their large data sets. For this purpose, it is necessary to consistently simulate different populations of galaxies, in particular Emission Line Galaxies (ELGs), less used in the past for cosmological purposes. In this work, we further the forward modeling approach presented in Fagioli et al. 2018, by extending the spectra simulator Uspec to model galaxies of different kinds with improved parameters from Tortorelli et al. 2020. Furthermore, we improve the modeling of the selection function by using the image simulator Ufig. We apply this to the Sloan Digital Sky Survey (SDSS), and simulate $\sim157,000$ multi-band images. We pre-process and analyse them to apply cuts for target selection, and finally simulate SDSS/BOSS DR14 galaxy spectra. We compute photometric, astrometric and spectroscopic properties for red and blue, real and simulated galaxies, finding very good agreement. We compare the statistical properties of the samples by decomposing them with Principal Component Analysis (PCA). We find very good agreement for red galaxies and a good, but less pronounced one, for blue galaxies, as expected given the known difficulty of simulating those. Finally, we derive stellar population properties, mass-to-light ratios, ages and metallicities, for all samples, finding again very good agreement. This shows how this method can be used not only to forecast cosmology surveys, but it is also able to provide insights into studies of galaxy formation and evolution.

[4]  arXiv:2002.04040 [pdf, other]

Title: ALMA reveals the molecular gas properties of 5 star-forming galaxies across the main sequence at 3 < z < 3.5

Authors: Paolo Cassata, Daizhong Liu, Brent Groves, Eva Schinnerer, Eduardo Ibar, Mark Sargent, Alexander Karim, Margherita Talia, Olivier Le Fevre, Lidia Tasca, Brian C. Lemaux, Bruno Ribeiro, Stefano Fiore, Michael Romano, Chiara Mancini, Laura Morselli, Giulia Rodighiero, Lucia Rodriguez-Munoz, Andrea Enia, Vernesa Smolcic

Comments: 17 pages, 8 figures; accepted for publication in The Astrophysical Journal

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

We present the detection of CO(5-4) with S/N> 7 - 13 and a lower CO transition with S/N > 3 (CO(4-3) for 4 galaxies, and CO(3-2) for one) with ALMA in band 3 and 4 in five main sequence star-forming galaxies with stellar masses 3-6x10^10 M/M_sun at 3 < z < 3.5. We find a good correlation between the total far-infrared luminosity LFIR and the luminosity of the CO(5-4) transition L'CO(5-4), where L'CO(5-4) increases with SFR, indicating that CO(5-4) is a good tracer of the obscured SFR in these galaxies. The two galaxies that lie closer to the star-forming main sequence have CO SLED slopes that are comparable to other star-forming populations, such as local SMGs and BzK star-forming galaxies; the three objects with higher specific star formation rates (sSFR) have far steeper CO SLEDs, which possibly indicates a more concentrated episode of star formation. By exploiting the CO SLED slopes to extrapolate the luminosity of the CO(1-0) transition, and using a classical conversion factor for main sequence galaxies of alpha_CO = 3.8 M_sun(K km s^-1 pc^-2)^-1, we find that these galaxies are very gas rich, with molecular gas fractions between 60 and 80%, and quite long depletion times, between 0.2 and 1 Gyr. Finally, we obtain dynamical masses that are comparable with the sum of stellar and gas mass (at least for four out of five galaxies), allowing us to put a first constraint on the alpha_CO parameter for main sequence galaxies at an unprecedented redshift.

[5]  arXiv:2002.04045 [pdf, other]

Title: The Obelisk simulation: galaxies contribute more than AGN to HI reionization of protoclusters

Authors: Maxime Trebitsch, Yohan Dubois, Marta Volonteri, Hugo Pfister, Corentin Cadiou, Harley Katz, Joakim Rosdahl, Taysun Kimm, Christophe Pichon, Ricarda S. Beckmann, Julien Devriendt, Adrianne Slyz

Comments: 21+4 pages, 18+1 figures, submitted to Astronomy & Astrophysics

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

We present the Obelisk project, a cosmological radiation-hydrodynamics simulation following the assembly and reionization of a protocluster progenitor during the first two billions of years from the big bang, down to $z = 3.5$. The simulation resolves haloes down to the atomic cooling limit, and tracks the contribution of different sources of ionization: stars, active galactic nuclei, and collisions. The Obelisk project is designed specifically to study the coevolution of high redshift galaxies and quasars in an environment favouring black hole growth. In this paper, we establish the relative contribution of these two sources of radiation to reionization and their respective role in establishing and maintaining the high redshift ionizing background. Our volume is typical of an overdense region of the Universe and displays star formation rate and black hole accretion rate densities similar to high redshift protoclusters. We find that hydrogen reionization happens inside-out and is completed by $z \sim 6$ in our overdensity, and is predominantly driven by galaxies, while accreting black holes only play a role at $z \sim 4$.

[6]  arXiv:2002.04046 [pdf, ps, other]

Title: Subaru Infrared Adaptive Optics-assisted High-spatial-resolution Imaging Search for Luminous Dual Active Galactic Nuclei in Nearby Ultraluminous Infrared Galaxies

Authors: Masatoshi Imanishi (1,2), Taiki Kawamuro (1), Satoshi Kikuta (1,2), Suzuka Nakano (1,2), Yuriko Saito (1,2) ((1) NAOJ, (2) GUAS/SOKENDAI)

Comments: 29 pages, 6 Figures (preprint style). Accepted for publication in ApJ. Resolutions of some figures are degraded

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

We present infrared K'- (2.1 micron) and L'-band (3.8 micron) high-spatial-resolution (<0.3") imaging observations of 17 nearby (z < 0.17) ultraluminous infrared galaxies (ULIRGs) assisted with the adaptive optics of the Subaru Telescope. We search for compact red K'-L' color emission as the indicator of luminous active galactic nuclei (AGNs) due to AGN-heated hot dust emission. Two luminous dual AGN candidates are revealed. Combining these results with those of our previous study, we can state that the detected fraction of luminous dual AGNs in nearby ULIRGs is much less than unity (<20%), even when infrared wavelengths >2 micron are used that should be sensitive to buried AGNs due to small dust extinction effects. For ULIRGs with resolved multiple nuclear K'-band emission, we estimate the activation of supermassive black holes (SMBHs) at individual galaxy nuclei in the form of AGN luminosity normalized by SMBH mass inferred from host galaxy stellar luminosity. We confirm a trend that more massive SMBHs in K'-band brighter primary galaxy nuclei are generally more active, with higher SMBH-mass-normalized AGN luminosity than less massive SMBHs in K'-band fainter secondary galaxy nuclei, as predicted by numerical simulations of gas-rich major galaxy mergers. In two sources, the presence of even infrared elusive extremely deeply buried AGNs is indicated by comparisons with available (sub)millimeter data. Non-synchronous SMBH activation (i.e., less activation of less massive SMBHs) and the possible presence of such infrared elusive AGNs may be responsible for the small fraction of infrared-detected luminous dual AGNs in nearby merging ULIRGs.

[7]  arXiv:2002.04056 [pdf]

Title: The shock driving capability of a CME inferred from multiwavelength observations

Authors: Fithanegest Kassa Dagnew, Nat Gopalswamy, Solomon Belay Tessema, Ange Cynthia Umuhire, Seiji Yashiro, Pertti Mäkelä, Hong Xie

Comments: 15 pages, 6 figures, accepted for publication in Sun and Geosphere, a special issue devoted to ISWI-2019

Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Space Physics (physics.space-ph)

The radial speed of a coronal mass ejection (CME) determines the shock-driving capability of a CME as indicated by the presence of a type II radio burst. Here we report on the April 18, 2014 CME that was associated with a type II radio burst in the metric and interplanetary domains. We used the radio-burst data provided by the San Vito Solar Observatory of the Radio Solar Telescope Network and data from the Wind spacecraft. The CME is a full halo in the field of view of the coronagraphs on board the Solar and Heliospheric Observatory (SOHO). The CME was also observed by the coronagraphs on board the Solar Terrestrial Relations Observatory (STEREO). We computed the CME shock and flux rope speeds based on the multi-view observations by the different coronagraphs and by EUV instruments. We determined the shock speed from metric and interplanetary radio observations and found them to be consistent with white-light observations, provided the metric type II burst and its continuation into the decameter-hectometric domain are produced at the shock flanks, where the speed is still high enough to accelerate electrons that produce the type II bursts. Interestingly, there was an interplanetary type II burst segment consistent with an origin at the shock nose suggesting that the curved shock was crossing plasma levels separated by a few solar radii. We conclude that the CME speed is high enough to produce the interplanetary Type II burst and a solar energetic particle (SEP) event. However, the speed is not high enough to produce a ground level enhancement (GLE) event, which requires the shock to form at a height of ~1.5 Rs.

[8]  arXiv:2002.04073 [pdf, ps, other]

Title: Investigating Opacity Modifications and Reaction Rate Uncertainties to Resolve the Cepheid Mass Discrepancy

Authors: Joyce A. Guzik (1), Ebraheem Farag (2), Jakub Ostrowski (3), Nancy R. Evans (4), Hilding Neilson (5), Sofia Moschou (4), Jeremy J. Drake (4) ((1) Los Alamos National Laboratory, Los Alamos, NM, USA, (2) Arizona State U., Tempe, AZ, USA, (3) Pedagogical U. of Cracow, Krakow, Poland, (4) Harvard Smithsonian Center for Astrophysics, Cambridge, MA, USA, (5), U. Toronto, Toronto, ON, Canada)

Comments: 5 pages, 3 figures, submitted for Astronomical Society of the Pacific Conference Series "RRLyrae/Cepheid2019: Frontiers of Classical Pulsators: Theory and Observations", Cloudcroft, NM, USA October 13-18, 2019

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

Cepheid masses derived from pulsations or binary dynamics are generally lower than those derived from stellar evolution models. Recent efforts have been dedicated to investigating the effects of abundances, mass loss, rotation, convection and overshooting prescriptions for modifying the evolution tracks to reduce or remove this Cepheid mass discrepancy. While these approaches are promising, either alone or in combination, more work is required to distinguish between possible solutions. Here we investigate nuclear reaction rate and opacity modifications on Cepheid evolution using the MESA code. We discuss the effects of opacity increases at envelope temperatures of 200,000-400,000 K proposed to explain the pulsation properties of hybrid main-sequence beta Cep/Slowly Pulsating B (SPB) variables which will evolve into Cepheids. We make use of the RSP nonlinear radial pulsation modeling capability in MESA to calculate periods and radial velocity amplitudes of Galactic Cepheids V1334 Cyg, Polaris, and delta Cep.

[9]  arXiv:2002.04075 [pdf]

Title: Trans-Neptunian binaries (2018)

Authors: Keith S. Noll, William M. Grundy, David Nesvorny, Audrey Thirouin

Comments: 22 pages, 9 figures, 1 table

Journal-ref: The Trans-Neptunian Solar System, Edited by Dina Prialnik, Maria Antoinetta Barucci, Leslie Young. ISBN: 9780128164907. Elsevier, 2020., p.201-224

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

The discovery and characteristics of transneptunian binaries are reviewed. In the 20 years since their first discovery, a wealth of detail has emerged including the frequency of binaries in different populations, their relative sizes and separations, and colors. Taken globally, these properties give strong clues to the origin and evolution of the populations where these binaries are found. In the last ten years and increasing number of binary orbits have been determined which yields a new trove of information on their masses and densities as well as details of their orbits including inclination, eccentricity and the timing of mutual events. In 2018, the study of transneptunian binaries remains one of the most active areas of progress in understanding the Solar System beyond Neptune.

[10]  arXiv:2002.04080 [pdf, other]

Title: The Solar Probe ANalyzers -- Electrons on Parker Solar Probe

Authors: Phyllis L Whittlesey (1), Davin E Larson (1), Justin C Kasper (2) (3), Jasper Halekas (4), Mamuda Abatcha (1), Robert Abiad (1), M. Berthomier (5), A. W. Case (3), Jianxin Chen (6), David W Curtis (1), Gregory Dalton (1), Kristopher G Klein (7), Kelly E Korreck (3), Roberto Livi (1), Michael Ludlam (1), Mario Marckwordt (1), Ali Rahmati (1), Miles Robinson (1), Amanda Slagle (1), M L Stevens (3), Chris Tiu (8), J L Verniero (1) ((1) University of California, Berkeley, CA, USA, (2) University of Michigan, Ann Arbor, MI, USA, (3) Smithsonian Astrophysical Observatory, Cambridge, MA, USA, (4) Department of Physics and Astronomy, University of Iowa, Iowa City, Iowa, USA, (5) Laboratoire de Physique des Plasmas, CNRS, Sorbonne Universite, Ecole Polytechnique, Observatoire de Paris, Universite Paris-Saclay, Paris, France, (6) Baja Technology LLC, Tempe, AZ, USA, (7) Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ, USA, (8) Heliophysics Science Division, NASA, Goddard Space Flight Center, Greenbelt, MD, USA)

Comments: This draft has been Accepted in the Astrophysical Journal Special issue for Parker Solar Probe

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

Electrostatic analyzers of different designs have been used since the earliest days of the space age, beginning with the very earliest solar wind measurements made by Mariner 2 en route to Venus in 1962. The Parker Solar Probe (PSP) mission, NASA's first dedicated mission to study the innermost reaches of the heliosphere, makes its thermal plasma measurements using a suite of instruments called the Solar Wind Electrons, Alphas, and Protons (SWEAP) investigation. SWEAP's electron Parker Solar Probe Analyzer (SPAN-E) instruments are a pair of top-hat electrostatic analyzers on PSP that are capable of measuring the electron distribution function in the solar wind from 2 eV to 30 keV. For the first time, in-situ measurements of thermal electrons provided by SPAN-E will help reveal the heating and acceleration mechanisms driving the evolution of the solar wind at the points of acceleration and heating, closer than ever before to the Sun. This paper details the design of the SPAN-E sensors and their operation, data formats, and measurement caveats from Parker Solar Probe's first two close encounters with the Sun.

[11]  arXiv:2002.04097 [pdf, ps, other]

Title: Renyi entropy and the holographic dark energy in flat space time

Authors: Tayeb Golanbari, Khaled Saaidi, Parvin Karimi

Comments: 7 pages, 10 figures

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

Based on Renyi entropy, we study the entropy corrected version of the holographic dark energy (HDE) model in apparent horizon of spatially flat FLRW universe. Applying the generalized entropy leads to the modified version of the Friedmann evolution equations which besides pressure-less matter and HDE, there is an extra term that is purely geometric. This extra term are assumed as another part of dark energy. We assume the universe is filled by non-interacting components of ideal fluids such as dark matter and holographic dark energy. The total dark energy, which is a combination of generalized HDE and geometric part, has a density parameter that approaches one by decreasing the redshift. Considering the total equation of state parameter and deceleration parameter of the universe indicates that the universe could stays in positive accelerated expansion phase that shows an agreement with observational data, only for the specific values of the constant $\zeta$.

[12]  arXiv:2002.04107 [pdf, other]

Title: Lyman-$α$ Polarization Intensity Mapping

Authors: Lluís Mas-Ribas, Tzu-Ching Chang

Comments: Phys. Rev. D, submitted. Main plots: figs. 3, 8, 9

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

We present a formalism that incorporates hydrogen Lyman-alpha (Ly$\alpha$) polarization arising from the scattering of radiation in galaxy halos into the intensity mapping approach. Using the halo model, and emission profiles based on simulations and observations, we calculate auto and cross power spectra at redshifts $3\leq z \leq13$ for the Ly$\alpha$ total intensity, $I$, polarized intensity, $P$, degree of polarization, $\Pi=P/I$, and two new quantities, the astrophysical $E$ and $B$ modes of Ly$\alpha$ polarization. The one-halo terms of the $\Pi$ power spectra show a turnover that signals the average extent of the polarization signal, and thus the extent of the scattering medium. The position of this feature depends on redshift, and on the specific emission profile shape and extent, in our formalism. Therefore, the comparison of various Ly$\alpha$ polarization quantities and redshifts can break degeneracies between competing effects, and it can reveal the true shape of the emission profiles, and thus, the physical properties of the cool gas in halos. Furthermore, measurements of Ly$\alpha$ $E$ and $B$ modes may be used as probes of galaxy evolution, because they are related to the average degree of anisotropy in the emission and in the halo gas distribution across redshifts. The detection of the polarization signal at $z \sim 3-5$ requires improvements in the sensitivity of current ground-based experiments by a factor of $\sim 10$, and of $\sim 100$ for space-based instruments targeting the redshifts $z\sim 9-10$, the exact values depending on the specific redshift and experiment. Interloper contamination in polarization is expected to be small, because the interlopers need to also be polarized. Overall, Ly$\alpha$ polarization boosts the amount of physical information retrievable on galaxies and their surroundings, most of it not achievable with total emission alone. (abridged)

[13]  arXiv:2002.04113 [pdf, other]

Title: From SN2010da to NGC 300 ULX-1: Ten Years of Observations of an Unusual High Mass X-ray Binary in NGC 300

Authors: Breanna A. Binder, Stefania Carpano, Marianne Heida, Ryan Lau

Comments: Accepted to special edition of Galaxies: High-Mass X-ray Binaries and Ultraluminous X-ray Sources Hosting Neutron Stars

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

In 2010 May, an intermediate luminosity optical transient was discovered in the nearby galaxy NGC 300 by a South African amateur astronomer. In the decade since its discovery, multi-wavelength observations of the misnamed ``SN 2010da'' have continually re-shaped our understanding of this high mass X-ray binary system. In this review, we present an overview of the multi-wavelength observations and attempts to understand the 2010 transient event and, later, the re-classification of this system as NGC~300 ULX-1: a red supergiant + neutron star ultraluminous X-ray source.

[14]  arXiv:2002.04119 [pdf, other]

Title: A decade of multi-wavelength observations of the TeV blazar 1ES 1215+303: Extreme shift of the synchrotron peak frequency and long-term optical-gamma-ray flux increase

Authors: Janeth Valverde, Deirdre Horan, Denis Bernard, Stephen Fegan (Fermi-LAT collaboration), A. U. Abeysekara, A. Archer, W. Benbow, R. Bird, A. Brill, R. Brose, M. Buchovecky, J. H. Buckley, J. L. Christiansen, W. Cui, A. Falcone, Q. Feng, J. P. Finley, L. Fortson, A. Furniss, A. Gent, G. H. Gillanders, C. Giuri, O. Gueta, D. Hanna, T. Hassan, O. Hervet, J. Holder, G. Hughes, T. B. Humensky, P. Kaaret, N. Kelley-Hoskins, M. Kertzman, D. Kieda, M. Krause, F. Krennrich, M. J. Lang, G. Maier, P. Moriarty, R. Mukherjee, D. Nieto, M. Nievas-Rosillo, S. O'Brien, R. A. Ong, A. N. Otte, N. Park, A. Petrashyk, K. Pfrang, A. Pichel, M. Pohl, R. R. Prado, E. Pueschel, J. Quinn, K. Ragan, P. T. Reynolds, Ribeiro, G. T. Richards, E. Roache, I. Sadeh, M. Santander, S. S. Scott, G. H. Sembroski, K. Shahinyan, et al. (27 additional authors not shown)

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

Blazars are known for their variability on a wide range of timescales at all wavelengths. Most studies of TeV gamma-ray blazars focus on short timescales, especially during flares. With a decade of observations from the Fermi-LAT and VERITAS, we present an extensive study of the long-term multi-wavelength radio-to-gamma-ray flux-density variability, with the addition of a couple of short-time radio-structure and optical polarization observations of the blazar 1ES 1215+303 (z=0.130), with a focus on its gamma-ray emission from 100 MeV to 30 TeV. Multiple strong GeV gamma-ray flares, a long-term increase in the gamma-ray and optical flux baseline and a linear correlation between these two bands are observed over the ten-year period. Typical HBL behaviors are identified in the radio morphology and broadband spectrum of the source. Three stationary features in the innermost jet are resolved by VLBA at 43.1, 22.2, and 15.3 GHz. We employ a two-component synchrotron self-Compton model to describe different flux states of the source, including the epoch during which an extreme shift in energy of the synchrotron peak frequency from infrared to soft X-rays is observed.

[15]  arXiv:2002.04132 [pdf, other]

Title: Europa's surface water ice crystallinity: Discrepancy between observations and thermophysical and particle flux modeling

Authors: Jodi R. Berdis, Murthy S. Gudipati, James R. Murphy, Nancy J. Chanover

Comments: 27 pages, 6 figures, accepted for publication in Icarus

Journal-ref: Icarus, Volume 341, May 2020, 113660. https://doi.org/10.1016/j.icarus.2020.113660

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

Physical processing of Europan surface water ice by thermal relaxation, charged particle bombardment, and possible cryovolcanic activity can alter the percentage of the crystalline form of water ice compared to that of the amorphous form of water ice (the ''crystallinity'') on Europa's surface. The timescales over which amorphous water ice is thermally transformed to crystalline water ice at Europan surface temperatures suggests that the water ice there should be primarily in the crystalline form, however, surface bombardment by charged particles induced by Jupiter's magnetic field, and vapor deposition of water ice from Europan plumes, can produce amorphous water ice surface deposits on short timescales. The purpose of this investigation is to determine whether the Europan surface water ice crystallinity derived from ground-based spectroscopic measurements is in agreement with the crystallinity expected based on temperature and radiation modeling. Using a 1D thermophysical model of Europa's surface, we calculate a full-disk crystallinity of Europa's leading hemisphere by incorporating the thermal relaxation of amorphous to crystalline water ice and the degradation of crystalline to amorphous water ice by irradiation. Concurrently, we derive the full-disk crystallinity of Europa's leading hemisphere using a comparison of near-infrared ground-based spectral observations from Grundy et al. (1999), Busarev et al. (2018), and the Apache Point Observatory with laboratory spectra from Mastrapa et al. (2018) and the Ice Spectroscopy Lab at the Jet Propulsion Laboratory. We calculate a modeled crystallinity significantly higher than crystallinities derived from ground-based observations and laboratory spectra. This discrepancy may be a result of geophysical processes, such as by vapor-deposited plume material, or it may arise from assumptions and uncertainties in the crystallinity calculations.

[16]  arXiv:2002.04163 [pdf, other]

Title: Cosmic-ray Antinuclei as Messengers of New Physics: Status and Outlook for the New Decade

Authors: P. von Doetinchem, K. Perez, T. Aramaki, S. Baker, S. Barwick, R. Bird, M. Boezio, S.E. Boggs, M. Cui, A. Datta, F. Donato, C. Evoli, L. Fabris, L. Fabbietti, E. Ferronato Bueno, N. Fornengo, H. Fuke, C. Gerrity, D. Gomez Coral, C. Hailey, D. Hooper, M. Kachelriess, M. Korsmeier, M. Kozai, R. Lea, N. Li, A. Lowell, M. Manghisoni, I.V. Moskalenko, R. Munini, M. Naskret, T. Nelson, K.C.Y. Ng, F. Nozzoli, A. Oliva, R.A. Ong, G. Osteria, T. Pierog, V. Poulin, S. Profumo, T. Poeschl, S. Quinn, V.Re, F. Rogers, J. Ryan, N. Saffold, K. Sakai, P. Salati, S. Schael, L. Serksnyte, A. Shukla, A. Stoessl, J. Tjemsland, E. Vannuccini, M. Vecchi, M.W. Winkler, D. Wright, M. Xiao, W. Xu, T. Yoshida, G. Zampa, P. Zuccon

Comments: 42 pages, 14 figures

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

The precise measurement of cosmic-ray antinuclei serves as an important means for identifying the nature of dark matter and other new astrophysical phenomena, and could be used with other cosmic-ray species to understand cosmic-ray production and propagation in the Galaxy. For instance, low-energy antideuterons would provide a "smoking gun" signature of dark matter annihilation or decay, essentially free of astrophysical background. Studies in recent years have emphasized that models for cosmic-ray antideuterons must be considered together with the abundant cosmic antiprotons and any potential observation of antihelium. Therefore, a second dedicated Antideuteron Workshop was organized at UCLA in March 2019, bringing together a community of theorists and experimentalists to review the status of current observations of cosmic-ray antinuclei, the theoretical work towards understanding these signatures, and the potential of upcoming measurements to illuminate ongoing controversies. This review aims to synthesize this recent work and present implications for the upcoming decade of antinuclei observations and searches. This includes discussion of a possible dark matter signature in the AMS-02 antiproton spectrum, the most recent limits from BESS Polar-II on the cosmic antideuteron flux, and reports of candidate antihelium events by AMS-02; recent collider and cosmic-ray measurements relevant for antinuclei production models; the state of cosmic-ray transport models in light of AMS-02 and Voyager data; and the prospects for upcoming experiments, such as GAPS. This provides a roadmap for progress on cosmic antinuclei signatures of dark matter in the coming years.

[17]  arXiv:2002.04182 [pdf, other]

Title: Kinematic decomposition of IllustrisTNG disk galaxies: morphology and relation with morphological structures

Authors: Min Du, Luis C. Ho, Victor P. Debattista, Annalisa Pillepich, Dylan Nelson, Dongyao Zhao, Lars Hernquist

Comments: 19 pages, 13 figures. Submitted to ApJ, comments welcome. The mass fraction catalogue and images of the kinematically derived galactic structures are publicly available (this https URL)

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

We recently developed an automated method, auto-GMM, to kinematically decompose simulated galaxies. It extracts the kinematic structures in an accurate, efficient, and unsupervised way. Here we use auto-GMM to study the stellar kinematic structures of disk galaxies from the TNG100 run of the cosmological suite IllustrisTNG. We identify four to five kinematic structures that are commonly present among the diverse galaxy population. Structures having strong to moderate rotation are defined as cold and warm disks, respectively. Spheroidal structures dominated by random motions are classified as bulges or stellar halos, depending on how tightly bound they are. Disky bulges are defined as structures that have moderate rotation but compact morphology. TNG100 returns multiple structures that have reasonable properties, qualitatively consistent with our general expectations. Across all disky galaxies and accounting for the stellar mass within 3 half-mass radii, the kinematic spheroidal structures, obtained by summing up stars of bulges and halos, contribute $\sim 45\%$ of the total stellar mass, while the disky structures constitute $\sim 55\%$. This study also provides important insights about the relationship between kinematically and morphologically derived galactic structures. Comparing the morphology of kinematic structures with that of traditional bulge+disk decomposition, we conclude: (1) the morphologically decomposed bulges are composite structures comprised of a slowly rotating bulge, an inner halo, and a disky bulge; (2) kinematically disky bulges, akin to what are commonly called pseudo bulges in observations, are compact disk-like components that have rotation similar to warm disks; (3) halos contribute almost $30\%$ of the surface density of the outer part of morphological disks when viewed face-on; and (4) both cold and warm disks are often truncated in central regions.

[18]  arXiv:2002.04194 [pdf, other]

Title: Astrophysical Tests of Screened Modified Gravity

Authors: Jeremy Sakstein

Comments: Published as part of the IJMPD special issue "Modified Gravity: Progresses and Outlook of Theories, Numerical Techniques and Observational Tests" edited by Baojiu Li and Kazuya Koyama

Journal-ref: Int.J.Mod.Phys. D27 (2018) no.15, 1848008

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

Screened modified gravity theories evade the solar system tests that have proved prohibitive for classical alternative gravity theories. In many cases, they do not fit into the PPN formalism. The environmental dependence of the screening has motivated a concerted effort to find new and novel probes of gravity using objects that are well-studied but have hitherto not been used to test gravity. Astrophysical objects---stars, galaxies, clusters---have proved competitive tools for this purpose since they occupy the partially-screened regime between solar system and the Hubble flow. In this article we review the current astrophysical tests of screened modified gravity theories.

[19]  arXiv:2002.04199 [pdf, ps, other]

Title: Inference on Accretion Flow Properties of XTE J1752-223 During Its 2009-10 Outburst

Authors: Kaushik Chatterjee, Dipak Debnath, Debjit Chatterjee, Arghajit Jana, S. K. Chakrabarti

Comments: 12 pages, 7 Figures, 3 Tables (Accepted for publication in MNRAS)

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

We carry out a detailed study of the spectral and the timing properties of the stellar-mass black hole candidate XTE J1752-223 during its 2009-10 outburst using RXTE PCA data in the $2.5-25$ keV energy range. Low frequency quasi-periodic oscillations (LFQPOs) are seen in the power density spectrum (PDS). The spectral analysis is done using two types of models: one is the combined disk black body plus power-law model and the other is Transonic flow solution based Two Component Advective Flow (TCAF) model. RXTE PCA was non-operational during 2009 Nov. 16 to 2010 Jan. 18 and thus we study light curve profiles and evolution of hardness ratios using MAXI GSC and Swift BAT data. Based on the evolution of the temporal and the spectral properties of the source during its 2009-10 outburst, we find that the object evolved through the following spectral states: hard, hard-intermediate and soft-intermediate/soft. From the TCAF model fitted spectral analysis, we also estimate the probable mass of the black hole to be in the range of $8.1-11.9$ $M_\odot$, and more precisely, the mass appears to be is $10\pm{1.9}~M_\odot$.

[20]  arXiv:2002.04200 [pdf, ps, other]

Title: FOXSI-2 Solar Microflares I : Multi-instrument Differential Emission Measure Analysis and Thermal Energies

Authors: P.S. Athiray, Juliana Vievering, Lindsay Glesener, Shin-nosuke Ishikawa, Noriyuki Narukage, Juan Camilo Buitrago-Casas, Sophie Musset, Andrew Inglis, Steven Christe, Sam Krucker, Daniel Ryan

Comments: Accepted for Publication in the Astrophysical Journal

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

In this paper we present the differential emission measures (DEMs) of two sub-A class microflares observed in hard X-rays (HXRs) by the FOXSI-2 sounding rocket experiment, on 2014 December 11. The second FOXSI (Focusing Optics X-ray Solar Imager) flight was coordinated with instruments Hinode/XRT and SDO/AIA, which provided observations in soft X-rays (SXR) and Extreme Ultraviolet (EUV). This unique dataset offers an unprecedented temperature coverage useful for characterizing the plasma temperature distribution of microflares. By combining data from FOXSI-2, XRT, and AIA, we determined a well-constrained DEM for the microflares. The resulting DEMs peak around 3MK and extend beyond 10MK. The emission measures determined from FOXSI-2 were lower than 10 26cm-5 for temperatures higher than 5MK; faint emission in this range is best measured in HXRs. The coordinated FOXSI-2 observations produce one of the few definitive measurements of the distribution and the amount of plasma above 5MK in microflares. We utilize the multi-thermal DEMs to calculate the amount of thermal energy released during both the microflares as ~ 5.0 x 10 28 ergs for Microflare 1 and ~ 1.6 x 10 28 ergs for Microflare 2. We also show the multi-thermal DEMs provide a more comprehensive thermal energy estimates than isothermal approximation, which systematically underestimates the amount of thermal energy released.

[21]  arXiv:2002.04201 [pdf, other]

Title: SN 2010kd: Photometric and Spectroscopic Analysis of a Slow-Decaying Superluminous Supernova

Authors: Amit Kumar, Shashi Bhushan Pandey, Reka Konyves-Toth, Ryan Staten, Jozsef Vinko, J. Craig Wheeler, Weikang Zheng, Alexei V. Filippenko, Robert Kehoe, Robert Quimby, Yuan Fang, Carl Akerlof, Tim A. Mckay, Emmanouil Chatzopoulos, Benjamin P. Thomas, Govinda Dhungana, Amar Aryan, Raya Dastidar, Anjasha Gangopadhyay, Rahul Gupta, Kuntal Misra, Brajesh Kumar, Nameeta Brahme, David Buckley

Comments: 26 pages, 16 figures, accepted for publication in ApJ

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

This paper presents data and analysis of SN 2010kd, a low-redshift ($z = 0.101$) H-deficient superluminous supernova (SLSN), based on ultraviolet/optical photometry and optical spectroscopy spanning between $-$28 and +194 days relative to $\mathit{B}$ band maximum light. The $\mathit{B}$ band light curve comparison of SN 2010kd with a subset of well-studied SLSNe I at comparable redshifts indicates that it is a slow-decaying PTF12dam like SLSN. Analytical light-curve modeling using the $\mathtt{Minim}$ code suggests that the bolometric light curve of SN 2010kd favors circumstellar matter interaction for the powering mechanism. $\mathtt{SYNAPPS}$ modeling of the early-phase spectra does not identify broad H or He lines, whereas the photospheric-phase spectra are dominated by O I, O II, C II, C IV and Si II, particularly, presence of both low and high-velocity components of O II and Si II lines. The nebular-phase spectra of SN 2010kd are dominated by O I and Ca II emission lines similar to those seen in other SLSNe I. The line velocities in SN 2010kd exhibit flatter evolution curves similar to SN 2015bn but with comparatively higher values. SN 2010kd shows a higher single-zone local thermodynamic equilibrium temperature in comparison to PTF12dam and SN 2015bn, and it has an upper O I ejected mass limit of $\sim 10~M_\odot$. The host of SN 2010kd is a dwarf galaxy with a high star-formation rate ($\sim 0.18 \pm 0.04~M_\odot$ yr$^{-1}$) and extreme emission lines.

[22]  arXiv:2002.04224 [pdf, ps, other]

Title: Star formation in cloud cores -- simulations and observations of dense molecular cores and the formation of solar mass stars

Authors: Christoph Federrath

Comments: 8 pages, 6 figures, invited review for IAU Symposium S345 (Origins: From the Protosun to the First Steps of Life)

Journal-ref: AU Symposium S345 (Origins: From the Protosun to the First Steps of Life), Volume 14, pp. 43-50 (2020)

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

Star formation is inefficient. Recent advances in numerical simulations and theoretical models of molecular clouds show that the combined effects of interstellar turbulence, magnetic fields and stellar feedback can explain the low efficiency of star formation. The star formation rate is highly sensitive to the driving mode of the turbulence. Solenoidal driving may be more important in the Central Molecular Zone, compared to more compressive driving agents in spiral-am clouds. Both theoretical and observational efforts are underway to determine the dominant driving mode of turbulence in different Galactic environments. New observations with ALMA, combined with other instruments such as CARMA, JCMT and the SMA begin to reveal the magnetic field structure of dense cores and protostellar disks, showing highly complex field geometries with ordered and turbulent field components. Such complex magnetic fields can give rise to a range of stellar masses and jet/outflow efficiencies in dense cores and protostellar accretion disks.

[23]  arXiv:2002.04229 [pdf, other]

Title: Shaping planetary nebulae with jets and the grazing envelope evolution

Authors: Noam Soker (Technion, Israel)

Comments: Will be submitted in 2 days to allow comments by readers

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

I argue that the high percentage of PNe that are shaped by jets show that main sequence stars in binary systems can accrete mass at a high rate from an accretion disk and launch jets. Not only this allows jets to shape PNe, but this also points to the importance of jets in other types of binary systems and in other processes. These processes include the grazing envelope evolution (GEE), the common envelope evolution (CEE), and the efficient conversion of kinetic energy to radiation in outflows. As well, the jets point to the possibility that many systems launch jets as they enter the CEE, possibly through a GEE phase. The other binary systems where jets might play significant roles include intermediate-luminosity optical transients (ILOTs), supernova impostors (including pre-explosion outbursts), post-CEE binary systems, post-GEE binary systems, and progenitors of neutron star binary systems and black hole binary systems. One of the immediate consequences is that the outflow of these systems is highly-non-spherical, including bipolar lobes, jets, and rings.

[24]  arXiv:2002.04266 [pdf]

Title: QZ Carinae Orbit of the Two Binary Pairs

Authors: Mark Blackford, Stan Walker, Edwin Budding, Greg Bolt, Dave Blane, Terry Bohlsen, Anthony Moffat, Herbert Pablo, Andrzej Pigulski, Adam Popowicz, Gregg Wade, Konstanze Zwintz

Comments: Accepted for publication in JAAVSO, 7 pages, 1 Table, 9 figures

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

We present an updated O-C diagram of the light-time variations of the eclipsing binary (component B) in the system QZ Carinae as it moves in the long-period orbit around the non-eclipsing pair (component A). This includes new Variable Stars South members' measures from 2017 to 2019, BRITE satellite observations in 2017 and 2018, and 100 previously unpublished measures made at Auckland Observatory from 1974 to 1978. We conclude that QZ Carinae has not yet completed one orbit of the two pairs since discovery in 1971. The duration of totality of primary eclipses was measured to be 0.295 +/- 0.02 day (7.08 +/-0.48 hours), rather longer than earlier values from light curve models. Other observational findings include the shape of primary and secondary eclipses and small-scale short-term brightness changes.

[25]  arXiv:2002.04270 [pdf, other]

Title: Comparison of automatic methods to detect sunspots in the Coimbra Observatory spectroheliograms

Authors: S. Carvalho, S. Gomes, T. Barata, A. Lourenco, N. Peixinho

Comments: submitted to Astronomy and Computing

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

The Astronomical Observatory of the University of Coimbra has a huge collection of solar images, acquired daily since 1926. From the beginning, only spectroheliograms in the CaiiK line has been recorded, and since 1989 in the H_alpha line also. Such dataset requires efficient tools to detect and analyze solar activity features. The objective of this work is to create a tool that allows to automatic detect sunspots, umbra, and penumbra, that can be applied to the entire dataset. To achieve this, two different approaches have been developed, one based on mathematical morphology and another based on the intensities of the digital levels of the pixels. Both approaches were applied to a subset of images with features identified visually by an experimented solar observer. The performance of both methods was compared through the metrics Precision, Recall and F-score. Another evaluation was made based on the catalogs from Heliophysics Features Catalog and the SILSO catalogue.

[26]  arXiv:2002.04277 [pdf, other]

Title: Atmospheric Temperature Effect in secondary cosmic rays observed with a two square meter ground-based detector

Authors: Irma Riádigos, Damián García-Castro, Diego González-Díaz, Vicente Pérez-Muñuzuri

Comments: 18 pages, 10 figures, Submitted to Earth and Space Science

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

A high resolution 2 m$^2$ tracking detector, based on timing Resistive Plate Chamber (tRPC) cells, has been installed at the Faculty of Physics of the University of Santiago de Compostela (Spain) in order to improve our understanding of the cosmic rays arriving at the Earth's surface. Following a short commisioning of the detector, a study of the atmospheric temperature effect of the secondary cosmic ray component was carried out. A method based on Principal Component Analysis (PCA) has been implemented in order to obtain the distribution of temperature coefficients, $W_T(h)$, using as input the measured rate of nearly vertical cosmic ray tracks, showing good agreement with the theoretical expectation. The method succesfully removes the correlation present between the different atmospheric layers, that would be dominant otherwise. We briefly describe the initial calibration and pressure correction procedures, essential to isolate the temperature effect. Overall, the measured cosmic ray rate displays the expected anticorrelation with the effective atmospheric temperature, through the coefficient $\alpha_T= -0.279 \pm 0.051 $ \%/K. Rates follow the seasonal variations, and unusual short-term events are clearly identified too.

[27]  arXiv:2002.04300 [pdf, other]

Title: Shapes of stellar activity cycles

Authors: T. Willamo, T. Hackman, J. J. Lehtinen, M. J. Käpylä, N. Olspert, M. Viviani, J. Warnecke

Comments: 12 pages, 12 figures

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

Magnetic activity cycles are an important phenomenon in both the Sun and other stars. The shape of the solar cycle is commonly characterised by a fast rise and a slower decline, but not much attention has been paid to the shape of cycles in other stars. Our aim is to study whether the asymmetric shape of the solar cycle is common in other stars as well, and compare the cycle asymmetry to other stellar parameters. We also study the differences in the shape of the solar cycle, depending on what activity indicator is used. The observations are also compared to simulated activity cycles. We use the chromospheric Ca II H&K data from the Mount Wilson Observatory HK Project. From this data set we identify 47 individual cycles from 18 stars. We use the statistical skewness of a cycle as a measure of its asymmetry, and compare this to other stellar parameters. A similar analysis has been done to magnetic cycles extracted from direct numerical magnetohydrodynamic simulations of solar-type convection zones. The shape of the solar cycle (fast rise and slower decline) is common in other stars as well, although the Sun has particularly asymmetric cycles. Cycle-to-cycle variations are large, but the average shape of a cycle is still fairly well represented by a sinusoid. We find only slight correlations between the cycle asymmetry and other stellar parameters. There are large differences in the shape of the solar cycle, depending on what activity indicator is used. In the simulated cycles, there is a difference in the symmetry of global simulations covering the full longitudinal range, hence capable of exciting non-axisymmetric dynamo modes, versus wedge simulations covering a partial extent in longitude, where only axisymmetric modes are possible. The former produce preferentially positive skewness, while the latter a negative one.

[28]  arXiv:2002.04310 [pdf, other]

Title: The effect of non-linear mutual friction on pulsar glitch sizes and rise times

Authors: Thomas Celora, Vadym Khomenko, Marco Antonelli, Brynmor Haskell

Comments: 12 pages, 12 figures

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

Observations of pulsar glitches have the potential to provide constraints on the dynamics of the high density interior of neutron stars. However, to do so, realistic glitch models must be constructed and compared to the data. We take a step towards this goal by testing non-linear models for the mutual friction force, which is responsible for the exchange of angular momentum between the neutron superfluid and the observable normal component in a glitch. In particular, we consider a non-linear dependence of the drag force on the relative velocity between superfluid vortices and the normal component, in which the contributions of both kelvon and phonon excitations are included. This non-linear model produces qualitatively new features, and is able to reproduce the observed bimodal distribution of glitch sizes in the pulsar population. The model also suggests that the differences in size distributions in individual pulsars may be due to the glitches being triggered in regions with different pinning strengths, as stronger pinning leads to higher vortex velocities and a qualitatively different mutual friction coupling with respect to the weak pinning case. Glitches in pulsars that appear to glitch quasi-periodically with similar sizes may thus be due to the same mechanisms as smaller events in pulsars that have no preferred glitch size, but simply originate in stronger pinning regions, possibly in the core of the star.

[29]  arXiv:2002.04329 [pdf, other]

Title: VVV WIN 1733$-$3349: a low extinction window to probe the far side of the Milky Way bulge

Authors: Roberto K. Saito, Dante Minniti, Robert A. Benjamin, Maria Gabriela Navarro, Javier Alonso-García, Oscar A. Gonzalez, Roberto Kammers, Francisco Surot

Comments: 5 pages, 4 figures. Accepted for publication in MNRAS Letters

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

Windows of low extinction in the Milky Way (MW) have been used along the past decades for the study of the Galactic structure and the stellar population across the inner bulge and disk. Here we report the analysis of another low extinction near-IR window discovered by the VISTA Variables in the V\'ia L\'actea Survey. VVV WIN 1733$-$3349 is about half a degree in size and is conveniently located right in the MW plane, at Galactic coordinates $(l, b) = (-5.2, -0.3)$. The mean extinction of VVV WIN 1733$-$3349 is $A_{Ks} = 0.61\pm0.08$ mag, which is much smaller than the extinction in the surrounding area. The excess in the star counts is consistent with the reduced extinction, and complemented by studying the distribution of red clump (RC) stars. Thanks to the strategic low-latitude location of VVV WIN 1733$-$3349, we are able to interpret their RC density fluctuations with the expected overdensities due to the presence of the spiral arms beyond the bulge. In addition, we find a clear excess in the number of microlensing events within the window, which corroborates our interpretation that VVV WIN 1733$-$3349 is revealing the far side of the MW bulge.

[30]  arXiv:2002.04340 [pdf, other]

Title: Streams, substructures and the early history of the Milky Way

Authors: Amina Helmi

Comments: 56 pages, 17 figures. High-resolution version available from this http URL Invited review to appear in Annual Reviews of Astronomy and Astrophysics

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

The advent of Gaia's 2nd data release in combination with large spectroscopic surveys are revolutionizing our understanding of the Galaxy. Thanks to these and the knowledge accumulated thus far, a more mature picture of the evolution of the early Milky Way is emerging:
* Two of the traditional Galactic components, i.e. the stellar halo and the thick disk, appear to be intimately linked: stars with halo-like kinematics originate in similar proportions, from a "heated" (thick) disk and from debris from a system named Gaia-Enceladus. Gaia-Enceladus was the last big merger event experienced by the Milky Way and probably completed around 10 Gyr ago. The puffed-up stars now present in the halo as a consequence of the merger have thus exposed the existence of a disk component at z ~ 1.8.
* The Helmi streams, Sequoia, and Thamnos are amongst the newly uncovered or better characterized merger events. Knowledge of their progenitor's properties, star formation and chemical histories is still incomplete.
* Debris' from different objects often overlap in phase-space. A task for the next years will be to use spectroscopic surveys for chemical labelling and to disentangle events from one another using dimensions other than only phase-space, metallicity or [alpha/Fe].
* These surveys will also provide line-of-sight velocities missing for faint stars and more accurate distance determinations for distant objects. The resulting samples of stars will cover a much wider volume of the Galaxy allowing, for example, linking kinematic substructures in the inner halo to spatial overdensities in the outer halo.
* All the results obtained so far are in-line with expectations of current cosmological models. Yet, tailored hydrodynamical simulations as well as "constrained" cosmological simulations are needed to push our knowledge of the assembly of the Milky Way back to the earliest times. [abridged]

[31]  arXiv:2002.04342 [pdf, other]

Title: Envelope-to-disk mass transport in the FUor-type young eruptive star V346 Normae

Authors: Á. Kóspál, P. Ábrahám, O. Fehér, F. Cruz-Saenz de Miera, M. Takami

Comments: 2 pages, 1 figure, published in "Origins: From the Protosun to the First Steps of Life. Proceedings of the International Astronomical Union, Volume 345"

Journal-ref: Origins: From the Protosun to the First Steps of Life. Proceedings of the International Astronomical Union, Volume 345, pp. 320-321 (2020)

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

Having disk-to-star accretion rates on the order of 10$^{-4}\,M_{\odot}$/yr, FU Orionis-type stars (FUors) are thought to be the visible examples for episodic accretion. FUors are often surrounded by massive envelopes, which replenish the disk material and enable the disk to produce accretion outbursts. We observed the FUor-type star V346 Nor with ALMA at 1.3~mm continuum and in different CO rotational lines. We mapped the density and velocity structure of its envelope and analyzed the results using channel maps, position-velocity diagrams, and spectro-astrometric methods. We discovered a pseudo-disk and a Keplerian disk around a 0.1 $M_{\odot}$ central star. We determined an infall rate from the envelope onto the disk of 6$\times$10$^{-6}\,M_{\odot}$/yr, a factor of few higher than the quiescent accretion rate from the disk onto the star. This hints for a mismatch between the infall and accretion rates as the cause of the eruption.

[32]  arXiv:2002.04352 [pdf, other]

Title: Quantum sensor networks as exotic field telescopes for multi-messenger astronomy

Authors: Conner Dailey, Colin Bradley, Derek F. Jackson Kimball, Ibrahim Sulai, Szymon Pustelny, Arne Wickenbrock, Andrei Derevianko

Comments: 19 pages, 5 figures

Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Experiment (hep-ex); Quantum Physics (quant-ph)

Multi-messenger astronomy, the coordinated observation of different classes of signals originating from the same astrophysical event, provides a wealth of information about astrophysical processes with far-reaching implications. So far, the focus of multi-messenger astronomy has been the search for conventional signals from known fundamental forces and standard model particles, like gravitational waves (GW). In addition to these known effects, quantum sensor networks could be used to search for astrophysical signals predicted by beyond-standard-model (BSM) theories. Exotic bosonic fields are ubiquitous features of BSM theories and appear while seeking to understand the nature of dark matter and dark energy and solve the hierarchy and strong CP problems. We consider the case where high-energy astrophysical events could produce intense bursts of exotic low-mass fields (ELFs). We propose to expand the toolbox of multi-messenger astronomy to include networks of precision quantum sensors that by design are shielded from or insensitive to conventional standard-model physics signals. We estimate ELF signal amplitudes, delays, rates, and distances of GW sources to which global networks of atomic magnetometers and atomic clocks could be sensitive. We find that, indeed, such precision quantum sensor networks can function as ELF telescopes to detect signals from sources generating ELF bursts of sufficient intensity. Thus ELFs, if they exist, could act as additional messengers for astrophysical events.

[33]  arXiv:2002.04377 [pdf, other]

Title: The Sixth Data Release of the Radial Velocity Experiment (RAVE) -- I: Survey Description, Spectra and Radial Velocities

Authors: Matthias Steinmetz, Gal Matijevic, Harry Enke, Tomaz Zwitter, Guillaume Guiglion, Paul J. McMillan, Georges Kordopatis, Marica Valentini, Cristina Chiappini, Luca Casagrande, Jennifer Wojno, Borja Anguiano, Olivier Bienayme, Albert Bijaoui, James Binney, Donna Burton, Paul Cass, Patrick de Laverny, Kristin Fiegert, Kenneth Freeman, Jon P. Fulbright, Brad K. Gibson, Gerard Gilmore, Eva K. Grebel, Amina Helmi, Andrea Kunder, Ulisse Munari, Julio F. Navarro, Quentin Parker, Gregory R. Ruchti, Alejandra Recio-Blanco, Warren Reid, George M. Seabroke, Alessandro Siviero, Arnaud Siebert, Milorad Stupar, Fred Watson, Mary E.K. Williams, Rosemary F.G. Wyse, Friedrich Anders, Teresa Antoja, Danijela Birko, Joss Bland-Hawthorn, Diego Bossini, Rafael A. Garcia, Ismael Carrillo, William J. Chaplin, Yvonne Elsworth, et al. (14 additional authors not shown)

Comments: 30 pages, 11 figures, submitted to AJ

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

We present part 1 of the 6th and final Data Release (DR6 or FDR) of the Radial Velocity Experiment (RAVE), a magnitude-limited (9<I<12) spectroscopic survey of Galactic stars randomly selected in the southern hemisphere. The RAVE medium-resolution spectra (R~7500) cover the Ca-triplet region (8410-8795A) and span the complete time frame from the start of RAVE observations on 12 April 2003 to their completion on 4 April 2013. Wavelength-calibrated and flux-normalized spectra for 518,387 observations of 451,783 unique stars are presented. The final data release presented in this publication consists of spectra, error spectra, spectral classification, derived radial velocities, and cross matches with other relevant catalogs. The data can be accessed via the RAVE Web site (this http URL) or the Vizier database.

[34]  arXiv:2002.04430 [pdf, other]

Title: A census of Coronal Mass Ejections on solar-like stars

Authors: M. Leitzinger, P. Odert, R. Greimel, K. Vida, L. Kriskovics, E.W. Guenther, H. Korhonen, F. Koller, A. Hanslmeier, Zs. Kővári, H. Lammer

Comments: MNRAS accepted

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

Coronal Mass Ejections (CMEs) may have major importance for planetary and stellar evolution. Stellar CME parameters, such as mass and velocity, have yet not been determined statistically. So far only a handful of stellar CMEs has been detected mainly on dMe stars using spectroscopic observations. We therefore aim for a statistical determination of CMEs of solar-like stars by using spectroscopic data from the ESO phase 3 and Polarbase archives. To identify stellar CMEs we use the Doppler signal in optical spectral lines being a signature of erupting filaments which are closely correlated to CMEs. We investigate more than 3700 hours of on-source time of in total 425 dF-dK stars. We find no signatures of CMEs and only few flares. To explain this low level of activity we derive upper limits for the non detections of CMEs and compare those with empirically modelled CME rates. To explain the low number of detected flares we adapt a flare power law derived from EUV data to the H{\alpha} regime, yielding more realistic results for H{\alpha} observations. In addition we examine the detectability of flares from the stars by extracting Sun-as-a-star H{\alpha} light curves. The extrapolated maximum numbers of observable CMEs are below the observationally determined upper limits, which indicates that the on-source times were mostly too short to detect stellar CMEs in H{\alpha}. We conclude that these non detections are related to observational biases in conjunction with a low level of activity of the investigated dF-dK stars.

[35]  arXiv:2002.04435 [pdf, other]

Title: A photometric mapping of the night sky brightness of the Maltese islands

Authors: Joseph Caruana, Ryan Vella, Daniel Spiteri, Michael Nolle, Sara Fenech, Noel J. Aquilina

Comments: 29 pages, 6 figures, 11 supplementary figures, accepted for publication in Journal of Environmental Management

Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Atmospheric and Oceanic Physics (physics.ao-ph)

Over the years, the Maltese Islands have seen a marked rise in the prevalence of artificial lighting at night. The most evident type of light pollution arising from this evolution in anthropogenic night-time lighting is artificial skyglow via partial back-scattering in the atmosphere, leading to an increase in the Night Sky Brightness (NSB). The importance of understanding and quantifying the geographical distribution of the NSB is underscored by the adverse impact of light pollution on various spheres, from astronomical observation to ecology and human health. For the first time, we present a detailed map of the NSB over the Maltese archipelago carried out with Unihedron Sky Quality Meters. We show that the vast majority of the area of the Maltese Islands is heavily light polluted, with 87% of the area registering a NSB $<$ 20.39~mag$_{\rm SQM}$/arcsec$^2$ (Bortle Class 5 or higher) and 37.3% $<$ 19.09~mag$_{\rm SQM}$/arcsec$^2$ (Bortle Class 6 or higher), with the Milky Way being visible for only 12.8% of the area (adopting a visibility threshold $>$ 20.4 - 21.29~mag$_{\rm SQM}$/arcsec$^2$; Bortle Class 4). Coastal Dark Sky Heritage Areas on the island of Gozo retain generally darker skies than the rest of the islands, but light pollution originating further inland is encroaching upon and adversely affecting these sites. The methodology presented in this study can be adopted for continued future studies in Malta as well as for other regions.

[36]  arXiv:2002.04454 [pdf, other]

Title: Joint XMM-Newton and NuSTAR observations of the reflection spectrum of III Zw 2

Authors: Wara Chamani, Karri Koljonen, Tuomas Savolainen

Comments: 12 pages, 8 figures, 6 tables, accepted for publication with A&A

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

Detecting and modelling the reprocessed hard X-ray emission component in the accretion flow, so-called reflection spectrum is a main tool to estimate black hole spins in a wide range of astrophysical black holes regardless of their mass or distance. In this work, we studied the X-ray spectra of the Seyfert I galaxy III Zw 2 using multi-epoch XMM-Newton, NuSTAR and Suzaku observations. The X-ray spectra exhibit a soft-excess below 1 keV and a prominent excess at the location of the broad Fe K{\alpha} line at 6.4 keV. To account for these spectral features, we have fitted the spectra with multiple models including an ionized partially covering absorber and an accretion disk reflection model. To fully resolve the reflection component, we analyzed jointly the XMM-Newton and NuSTAR observations taken in 2017 and archival XMM-Newton data from 2000. Assuming the reflection scenario, the resulting model fits support a rapidly spinning black hole (a > 0.98) in this radio-intermediate source. The X-ray spectra in 2000 and 2017 are remarkably similar with the only difference in the reflection fraction, possibly due to a change in the geometry of the accretion flow. However, the Suzaku observation is markedly different, and we suggest this could be an effect of a jet contribution in the X-ray band, which is supported by the elevated radio flux during this observation.

[37]  arXiv:2002.04468 [pdf, other]

Title: Consistent perturbative modeling of pseudo-Newtonian core-collapse supernova simulations

Authors: John Ryan Westernacher-Schneider

Comments: 11 pages, 9 figures, 2 tables. Journal submission will be delayed to allow for comments

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

We write down and apply the linearized fluid and gravitational equations consistent with pseudo-Newtonian simulations, whereby Newtonian hydrodynamics is used with a pseudo-Newtonian monopole and standard Newtonian gravity for higher multipoles. We thereby eliminate the need to use mode function matching to identify the active non-radial modes in pseudo-Newtonian core-collapse supernova simulations, in favor of the less complex and less costly mode frequency matching method. In doing so, we are able to measure appropriate boundary conditions for a mode calculation.

[38]  arXiv:2002.04489 [pdf, ps, other]

Title: AstroSat/LAXPC view of GX 17+2: Spectral Evolution along the Z-track

Authors: V. K. Agrawal, Anuj Nandi, M.C. Ramadevi

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

In this paper, we present the first results obtained using $\sim$ 50 ks observations of the bright low-mass X-ray binary (LMXB) GX 17+2 with Large Area X-ray Proportional Counter (LAXPC) onboard {\it AstroSat}. The source traced out a complete Z-track in the hardness intensity diagram (HID). The spectra at different sections of the Z-diagram are well described by either a combination of a thermal Comptonization component, a power-law and a relativistic iron line or a model consisting of a thermal disk component, a single temperature blackbody, a power-law and a relativistic iron line. Fitting the spectra with both phenomenological models suggests that the power-law component is strong in the horizontal branch (HB), becomes weaker as the source moves down the normal branch (NB) and then again becomes stronger as the sources moves up the flaring branch (FB). However, we find that the strength of the power-law component is model dependent, although the trend in the variation of the power-law strength along the Z-track is similar. A simple model composed by a Comptonized emission and power-law component, convolved with the ionized reflection, also describes the spectra very well.
A normal branch oscillation (NBO) with a centroid frequency 7.42$\pm$0.23 Hz, quality factor (Q) $\sim$ 4.88, rms 1.41$\pm$0.29\% and significance 5.1$\sigma$ is detected at the middle of the NB. The parameters of the Comptonized emission show a systematic evolution along the Z-diagram. The optical depth of the corona increases as the source moves up along the FB, suggesting possible trigger of an outflow or dumping of the disc material in to the corona by radiation pressure.

[39]  arXiv:2002.04490 [pdf, ps, other]

Title: Maser Flares Driven by Variations in Pumping and Background Radiation

Authors: M. D. Gray, S. Etoka, A.Travis, B. Pimpanuwat

Comments: 19 pages, 15 figures, accepted for publication in MNRAS

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

We simulate maser flares by varying either the pump rate or the background level of radiation in a 3D model of a maser cloud. We investigate the effect of different cloud shapes, saturation levels and viewpoints. Results are considered for clouds with both uniform and internally variable unsaturated inversion. Pumping and background variations are represented by several different driving functions, some of which are light curves drawn from observations. We summarise the pumping variability results in terms of three observable parameters, the maximum flux density achieved, a variability index and duty cycle. We demonstrate typical ranges of the flux density that may result from viewing an aspherical object from random viewpoints. The best object for a flare is a prolate cloud, viewed close to its long axis and driven from unsaturated conditions to at least modest saturation. Results for variation of the background level are qualitatively different from the variable pumping results in that they tend to produce short intervals of low flux density under conditions of moderate saturation and sufficient variability to be consistent with strong flaring. Variable background models typically have a significantly higher duty cycle than those with variable pumping.

[40]  arXiv:2002.04503 [pdf, ps, other]

Title: Chromospheric plasma ejection above a pore

Authors: L. Bharti, B. Shobha, C. Quintero Noda, C. Joshi, U. Pandya

Comments: 10 pages, 5 figures, accepted for publication in MNRAS

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

We present high spatial resolution observations of short lived transients, ribbon and jets like events above a pore in Ca II H images where fine structure like umbral dots, lightbridge and penumbral micro filaments are present in the underlying photosphere. We found that current layers are formed at the edges of convective fine structure due to the shear between their horizontal field and the ambient vertical field. High vertical electric current density patches are observed in the photosphere around these events which indicates the formation of a current sheet at the reconnection site. In the framework of past studies, low altitude reconnection could be the mechanism that produces such events. The reconnection is caused by an opposite polarity field produced by the bending of field lines by convective downflows at the edge of the pore fine structures.

[41]  arXiv:2002.04512 [pdf, other]

Title: The Sixth Data Release of the Radial Velocity Experiment (RAVE) -- II: Stellar Atmospheric Parameters, Chemical Abundances and Distances

Authors: Matthias Steinmetz, Guillaume Guiglion, Paul J. McMillan, Gal Matijevic, Harry Enke, Georges Kordopatis, Tomaz Zwitter, Marica Valentini, Cristina Chiappini, Luca Casagrande, Jennifer Wojno, Borja Anguiano, Olivier Bienayme, Albert Bijaoui, James Binney, Donna Burton, Paul Cass, Patrick de Laverny, Kristin Fiegert, Kenneth Freeman, Jon P. Fulbright, Brad K. Gibson, Gerard Gilmore, Eva K. Grebel, Amina Helmi, Andrea Kunder, Ulisse Munari, Julio F. Navarro, Quentin Parker, Gregory R. Ruchti, Alejandra Recio-Blanco, Warren Reid, George M. Seabroke, Alessandro Siviero, Arnaud Siebert, Milorad Stupar, Fred Watson, Mary E.K. Williams, Rosemary F.G. Wyse, Friedrich Anders, Teresa Antoja, Joss Bland-Hawthorn, Diego Bossini, Rafael A. Garcia, Ismael Carrillo, William J. Chaplin, Yvonne Elsworth, Benoit Famaey, et al. (13 additional authors not shown)

Comments: 63 pages, 33 figures, submitted to AJ

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

We present part 2 of the 6th and final Data Release (DR6 or FDR) of the Radial Velocity Experiment (RAVE), a magnitude-limited (9<I<12) spectroscopic survey of Galactic stars randomly selected in the southern hemisphere. The RAVE medium-resolution spectra (R~7500) cover the Ca-triplet region (8410-8795A) and span the complete time frame from the start of RAVE observations on 12 April 2003 to their completion on 4 April 2013. In the second of two publications, we present the data products derived from 518,387 observations of 451,783 unique stars using a suite of advanced reduction pipelines focussing on stellar atmospheric parameters, in particular purely spectroscopically derived stellar atmospheric parameters (Teff, logg, and the overall metallicity), enhanced stellar parameters inferred via a Bayesian pipeline using Gaia DR2 astrometric priors, and asteroseismically calibrated stellar parameters for giant stars based on asteroseismic observations for 699 K2 stars. In addition, we provide abundances of the elements Fe, Al, and Ni, as well as an overall [alpha/Fe] ratio obtained using a new pipeline based on the GAUGUIN optimization method that is able to deal with variable signal-to-noise ratios. The RAVE DR6 catalogs are cross matched with relevant astrometric and photometric catalogs, and are complemented by orbital parameters and effective temperatures based on the infrared flux method. The data can be accessed via the RAVE Web site (this http URL) or the Vizier database.

[42]  arXiv:2002.04542 [pdf, other]

Title: Full-Array Noise Performance of Deployment-Grade SuperSpec mm-wave On-Chip Spectrometers

Authors: K. S. Karkare, P. S. Barry, C. M. Bradford, S. Chapman, S. Doyle, J. Glenn, S. Gordon, S. Hailey-Dunsheath, R. M. J. Janssen, A. Kovacs, H. G. LeDuc, P. Mauskopf, R. McGeehan, J. Redford, E. Shirokoff, C. Tucker, J. Wheeler, J. Zmuidzinas

Comments: 8 pages, 5 figures. Accepted by the Journal of Low Temperature Physics (Proceedings of the 18th International Workshop on Low Temperature Detectors)

Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Astrophysics of Galaxies (astro-ph.GA)

SuperSpec is an on-chip filter-bank spectrometer designed for wideband moderate-resolution spectroscopy at millimeter wavelengths, employing TiN kinetic inductance detectors. SuperSpec technology will enable large-format spectroscopic integral field units suitable for high-redshift line intensity mapping and multi-object spectrographs. In previous results we have demonstrated noise performance in individual detectors suitable for photon noise limited ground-based observations at excellent mm-wave sites. In these proceedings we present the noise performance of a full $R\sim 275$ spectrometer measured using deployment-ready RF hardware and software. We report typical noise equivalent powers through the full device of $\sim 3 \times 10^{-16} \ \mathrm{W}/\sqrt{\mathrm{Hz}}$ at expected sky loadings, which are photon noise dominated. Based on these results, we plan to deploy a six-spectrometer demonstration instrument to the Large Millimeter Telescope in early 2020.

[43]  arXiv:2002.04545 [pdf, ps, other]

Title: No close companions to a sample of bright sdB stars

Authors: Roberto Silvotti, Roy H. Ostensen, John H. Telting

Comments: Proceedings of the 9th Meeting on Hot Subdwarfs and Related Objects (Hendaye, June 23-28, 2019)

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

In this article we present preliminary results on the upper limits to the mass of a companion for 8 apparently single subdwarf B stars, derived from high-precision radial velocity measurements obtained from Harps-N spectra. These limits, corresponding to a few Jupiter masses, show that these stars do not have close companions and keep open the unresolved question of the mechanism that caused the almost complete loss of the envelope for the giant precursors of these stars. For 4 stars with a larger data coverage, it was also possible to set upper limits to the mass of a more massive companion in a wider orbit.

[44]  arXiv:2002.04546 [pdf, other]

Title: Modelling the response of potassium vapour in resonance scattering spectroscopy

Authors: S J Hale, W J Chaplin, G R Davies, Y P Elsworth

Comments: 18 pages, 11 figures. Accepted by Journal of Physics B: 2020 February 11

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

Resonance scattering techniques are often used to study the properties of atoms and molecules. The Birmingham Solar Oscillations Network (BiSON) makes use of Resonance Scattering Spectroscopy by applying the known properties of potassium vapour to achieve ultra-precise Doppler velocity observations of oscillations of the Sun. We present a model of the resonance scattering properties of potassium vapour which can be used to determine the ideal operating vapour temperature and detector parameters within a spectrophotometer. The model is validated against a typical BiSON vapour cell using a tunable diode laser, where the model is fitted to observed absorption profiles at a range of temperatures. Finally we demonstrate using the model to determine the effects of varying scattering detector aperture size, and vapour temperature, and again validate against observed scattering profiles. Such information is essential when designing the next generation of BiSON spectrophotometers (BiSON:NG), where the aim is to make use of off-the-shelf components to simplify and miniaturise the instrumentation as much as practical.

[45]  arXiv:2002.04548 [pdf, ps, other]

Title: Synthetic spectroscopic indices for identifying multiple stellar populations in globular clusters

Authors: Emanuele Bertone, Miguel Chávez, J. César Mendoza

Comments: Accepted for publication in MNRAS main journal; 13 pages, 10 figures. The material presented in the paper is available through a dedicated web page: this https URL

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

We present an investigation of synthetic spectroscopic indices that can plausibly help in identifying the presence of multiple stellar populations in globular clusters. The study is based on a new grid of stellar model atmospheres and high-resolution (R=500,000) synthetic spectra, that consider chemical partitions that have been singled out in Galactic globular clusters. The database is composed of 3472 model atmospheres and theoretical spectra calculated with the collection of Fortran codes DFSYNTHE, ATLAS9 and SYNTHE, developed by Robert L. Kurucz. They cover a range of effective temperature from 4300 to 7000 K, surface gravity from 2.0 to 5.0 dex and four different chemical compositions. A set of 19 spectroscopic indices were calculated from a degraded version (R=2500) of the theoretical spectra dataset. The set includes five indices previously used in the context of globular clusters analyses and 14 indices that we have newly defined by maximizing the capability of differentiating the chemical compositions. We explored the effects of atmospheric parameters on the index values and identified the optimal spectral diagnostics that allow to trace the signatures of objects of different stellar populations, located in the main sequence, the red giant branch and the horizontal branch. We found a suitable set of indices, that mostly involve molecular bands (in particular NH, but also CH and CN), that are very promising for spectroscopically identifying multiple stellar populations in globular clusters.

[46]  arXiv:2002.04560 [pdf, ps, other]

Title: Temporal Evolution of the Inverse Evershed Flow

Authors: C. Beck, D.P. Choudhary

Comments: Accepted for publication in the Astrophysical Journal

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

The inverse Evershed flow (IEF) is an inflow of material into the penumbra of sunspots in the solar chromosphere that occurs along dark, elongated superpenumbral fibrils extending from about the outer edge of the moat cell to the sunspot. The IEF channels exhibit brightenings in the penumbra, where the supersonic IEF descends to the photosphere causing shock fronts with localized heating. We used an 1-hr time-series of spectroscopic observations of the chromospheric spectral lines of CaIIIR at 854nm and H$\alpha$ at 656nm taken with IBIS at the DST to investigate the temporal evolution of IEF channels. Complementary information on the photospheric magnetic field was obtained from observations with FIRS at 1083\nm and HMI. We find that individual IEF channels are long-lived (10-60min) and only show minor changes in position and flow speed during their life time. Initiation and termination of IEF channels takes several minutes. The IEF channels with line-of-sight velocities of about 10km/s show no lasting impact from transient or oscillatory phenomena with maximal velocity amplitudes of only about 1km/s that run along them. We could not detect any clear correlation of the location and evolution of IEF channels to local magnetic field properties in the photosphere in the penumbra or moving magnetic features in the sunspot moat. Our results support a picture of the IEF as a field-aligned siphon flow along arched loops. From our data we cannot determine if their evolution is controlled by events at the outer end in the moat or at the inner end in the penumbra.

[47]  arXiv:2002.04574 [pdf, other]

Title: Time-domain study of the young massive cluster Westerlund 2 with the Hubble Space Telescope. I

Authors: E. Sabbi, M. Gennaro, J. Anderson, V. Bajaj, N. Bastian, J.S. Gallagher, III, M. Gieles, D.J. Lennon, A. Nota, K.C. Sahu, P. Zeidler

Comments: 19 pages, 15 figures, accepted for publication on ApJ

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

Time-domain studies of pre-main sequence stars have long been used to investigate star properties during their early evolutionary phases and to trace the evolution of circumstellar environments. Historically these studies have been confined to the nearest, low-density, star forming regions. We used the Wide Field Camera 3 on board of the Hubble Space Telescope to extend, for the first time, the study of pre-main sequence variability to one of the few young massive clusters in the Milky Way, Westerlund 2. Our analysis reveals that at least 1/3 of the intermediate and low-mass pre-main sequence stars in Westerlund 2 are variable. Based on the characteristics of their light curves, we classified ~11% of the variable stars as weak-line T-Tauri candidates, ~ 52% as classical T-Tauri candidates, ~ 5% as dippers and ~26% as bursters. In addition, we found that 2% of the stars below 6Mo (~6% of the variables) are eclipsing binaries, with orbital periods shorter than 80 days. The spatial distribution of the different populations of variable pre-main sequence stars suggests that stellar feedback and UV-radiation from massive stars play an important role on the evolution of circumstellar and planetary disks.

[48]  arXiv:2002.04591 [pdf, other]

Title: Improving the background of gravitational-wave searches for core collapse supernovae: A machine learning approach

Authors: Marco Cavaglia, Sergio Gaudio, Travis Hansen, Kai Staats, Marek Szczepanczyk, Michele Zanolin

Comments: This is the version of the article before peer review or editing, as submitted by an author to Machine Learning: Science and Technology. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at this https URL

Journal-ref: M Cavaglia et al 2020 Mach. Learn.: Sci. Technol. 1 015005

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

Based on the prior O1-O2 observing runs, about 30% of the data collected by Advanced LIGO and Virgo in the next observing runs are expected to be single-interferometer data, i.e., they will be collected at times when only one detector in the network is operating in observing mode. Searches for gravitational wave signals from supernova events do not rely on matched filtering techniques because of the stochastic nature of the signals. If a Galactic supernova occurs during single-interferometer times, separation of its unmodelled gravitational-wave signal from noise will be even more difficult due to lack of coherence between detectors. We present a novel machine learning method to perform single-interferometer supernova searches based on the standard LIGO-Virgo coherentWave-Burst pipeline. We show that the method may be used to discriminate Galactic gravitational-wave supernova signals from noise transients, decrease the false alarm rate of the search, and improve the supernova detection reach of the detectors.

[49]  arXiv:2002.04595 [pdf, other]

Title: Precessing flaring magnetar as a source of repeating FRB 180916.J0158+65

Authors: Yuri Levin, Andrei M. Beloborodov, Ashley Bransgrove

Comments: 5 pages, submitted to ApJ Letters

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

Recently, CHIME detected periodicity in the bursting rate of the repeating FRB 180916.J0158+65. In a popular class of models, the fast radio bursts (FRBs) are created by giant magnetic flares of a hyper-active magnetar driven by fast ambipolar diffusion in the core. We point out that in this scenario the magnetar is expected to precess freely with a period of hours to weeks. The internal magnetic field $B\sim 10^{16}$G deforms the star, and magnetic flares induce sudden changes in magnetic stresses. The resulting torques and displacements of the principal axes of inertia are capable of pumping a significant amplitude of precession. The anisotropy of the flaring FRB activity, combined with precession, implies a strong periodic modulation of the visible bursting rate. The ultra-strong field invoked in the magnetar model provides: (1) energy for the frequent giant flares, (2) the high rate of ambipolar diffusion, releasing the magnetic energy on the timescale $\sim 10^9$s, (3) the core temperature $T\approx 10^9$K, likely above the critical temperature for neutron superfluidity, (4) strong magnetospheric torques, which efficiently spin down the star, and (5) deformation with ellipticity $\epsilon> 10^{-6}$, much greater than the rotational deformation. These conditions result in a precession with negligible viscous damping, and can explain the observed 16 day period in FRB 180916.J0158+65.

[50]  arXiv:2002.04601 [pdf, other]

Title: Simulating the Cosmic Neutrino Background using Collisionless Hydrodynamics

Authors: Derek Inman, Hao-ran Yu

Comments: 11 pages, 6 figures

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

The cosmic neutrino background is an important component of the Universe that is difficult to include in cosmological simulations due to the extremely large velocity dispersion of neutrino particles. We develop a new approach to simulate cosmic neutrinos that decomposes the Fermi-Dirac phase space into shells of constant speed and then evolves those shells using hydrodynamic equations. These collisionless hydrodynamic equations are chosen to match linear theory, free particle evolution and allow for superposition. We implement this method into the information-optimized cosmological $N$-body code CUBE and demonstrate that neutrino perturbations can be accurately resolved to at least $k\sim1\ h/$Mpc. This technique allows for neutrino memory requirements to be decreased by up to $\sim 10^3$ compared to traditional $N$-body methods.

[51]  arXiv:2002.04606 [pdf, other]

Title: SHADOWS: a spectro-gonio radiometer for bidirectional reflectance studies of dark meteorites and terrestrial analogs: design, calibrations, and performances on challenging surfaces

Authors: S. Potin, O. Brissaud, P. Beck, B. Schmitt, Y. Magnard, J.-J. Correia, P. Rabou, L. Jocou

Journal-ref: Applied Optics, vol. 57, pp 8279-8296 (2018)

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

We have developed a new spectro-gonio radiometer, SHADOWS, to study in the laboratory the bidirectional reflectance distribution function of dark and precious samples. The instrument operates over a wide spectral range from the visible to the near-infrared and is installed in a cold room. This paper presents the scientific and technical constraints of the spectro-gonio radiometer, its design and additional capabilities, as well as the performances and limitations of the instrument.

Cross-lists for Wed, 12 Feb 20

[52]  arXiv:2002.04038 (cross-list from hep-ph) [pdf, other]

Title: Co-SIMP Miracle

Authors: Juri Smirnov, John F. Beacom

Comments: 5 pages plus Supplemental Material, comments are welcome

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

We present a new mechanism for thermally produced dark matter, based on a semi-annihilation-like process, $\chi+ \chi +\text{SM} \rightarrow \chi + \text{SM}$, with intriguing consequences for the properties of dark matter. First, its mass is low, $\lesssim 1$ GeV (but $\gtrsim 5$ keV to avoid structure-formation constraints). Second, it is strongly interacting, leading to kinetic equilibrium between the dark and visible sectors, avoiding the structure-formation problems of $\chi+ \chi + \chi \rightarrow \chi + \chi$ models. Third, in the $3 \rightarrow 2$ process, one dark matter particle is consumed, giving the standard-model particle a monoenergetic recoil. We show that this new scenario is presently allowed, which is surprising (perhaps a ``minor miracle"). However, it can be systematically tested by novel analyses in present and near-term experiments.

[53]  arXiv:2002.04055 (cross-list from gr-qc) [pdf, other]

Title: Black hole superradiant instability from ultralight spin-2 fields

Authors: Richard Brito, Sara Grillo, Paolo Pani

Comments: 13 pages, 4 Figures

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

Ultralight bosonic fields are compelling dark-matter candidates and arise in a variety of beyond-Standard-Model scenarios. These fields can tap energy and angular momentum from spinning black holes through superradiant instabilities, during which a macroscopic bosonic condensate develops around the black hole. Striking features of this phenomenon include gaps in the spin-mass distribution of astrophysical black holes and a continuous gravitational-wave~(GW) signal emitted by the condensate. So far these processes have been studied in great detail for scalar fields and, more recently, for vector fields. Here we take an important step forward in the black-hole superradiance program by computing, analytically, the instability time scale, the direct GW emission, and the stochastic background, in the case of massive tensor (i.e., spin-$2$) fields. Our analysis is valid for any black hole spin and for small boson masses. The instability of massive spin-$2$ fields shares some properties with the scalar and vector cases, but its phenomenology is much richer, for example there exist multiple modes with comparable instability time scales, and the dominant GW signal is hexadecapolar rather than quadrupolar. Electromagnetic and GW observations of spinning black holes in the mass range $M\in(1,10^{10})M_\odot$ can be turned into a bound $10^{-10}\,{\rm eV/c^2}\lesssim m_b\lesssim 10^{-22}\,{\rm eV/c^2}$ on the mass of a putative spin-$2$ field. For $10^{-17}\,{\rm eV/c^2}\lesssim m_b\lesssim 10^{-15}\,{\rm eV/c^2}$, the space mission LISA could detect the continuous GW signal for sources at redshift $z=20$, or even larger.

[54]  arXiv:2002.04123 (cross-list from stat.CO) [pdf]

Title: Geometric nested sampling: sampling from distributions defined on non-trivial geometries

Authors: Kamran Javid

Comments: Peer reviewed and published in JOSS. arXiv admin note: substantial text overlap with arXiv:1905.09110

Journal-ref: JOSS 5(46), 1809, 2020

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

Metropolis Hastings nested sampling evolves a Markov chain, accepting new points along the chain according to a version of the Metropolis Hastings acceptance ratio, which has been modified to satisfy the nested sampling likelihood constraint. The geometric nested sampling algorithm I present here is based on the Metropolis Hastings method, but treats parameters as though they represent points on certain geometric objects, namely circles, tori and spheres. For parameters which represent points on a circle or torus, the trial distribution is "wrapped" around the domain of the posterior distribution such that samples cannot be rejected automatically when evaluating the Metropolis ratio due to being outside the sampling domain. Furthermore, this enhances the mobility of the sampler. For parameters which represent coordinates on the surface of a sphere, the algorithm transforms the parameters into a Cartesian coordinate system before sampling which again makes sure no samples are automatically rejected, and provides a physically intuitive way of the sampling the parameter space.

[55]  arXiv:2002.04287 (cross-list from physics.comp-ph) [pdf, other]

Title: Moving and Reactive Boundary Conditions in Moving-Mesh Hydrodynamics

Authors: Logan J. Prust

Comments: 12 pages, 8 figures, submitted to MNRAS

Subjects: Computational Physics (physics.comp-ph); Solar and Stellar Astrophysics (astro-ph.SR)

We outline the methodology of implementing moving boundary conditions into the moving-mesh code MANGA. The motion of our boundaries is reactive to hydrodynamic and gravitational forces. We discuss the hydrodynamics of a moving boundary as well as the modifications to our hydrodynamic and gravity solvers. Appropriate initial conditions to accurately produce a boundary of arbitrary shape are also discussed. Our code is applied to several test cases, including a Sod shock tube, a Sedov-Taylor blast wave and a supersonic wind on a sphere. We show the convergence of conserved quantities in our simulations. We demonstrate the use of moving boundaries in astrophysical settings by simulating a common envelope phase in a binary system, in which the companion object is modeled by a spherical boundary. We conclude that our methodology is suitable to simulate astrophysical systems using moving and reactive boundary conditions.

[56]  arXiv:2002.04294 (cross-list from hep-th) [pdf, ps, other]

Title: Cosmology from Quantum Information

Authors: Cesar Gomez, Raul Jimenez

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

We describe inflation in terms of a time dependent quantum density matrix with time playing the role of a stochastic variable. Using a quasi-de Sitter model we compute the corresponding quantum Fisher information function as the second derivative of the relative entanglement entropy for the density matrix at two different times. Employing standard quantum estimation theory we evaluate the minimal variance of quantum scalar fluctuations that reproduces the power spectrum and the corresponding tilt in the slow roll limit. The Jeffreys prior associated with such Fisher information can be used to define the probabilities on the set of initial conditions defined by the slow roll parameter $\epsilon$ and the initial Shannon information.

[57]  arXiv:2002.04409 (cross-list from physics.plasm-ph) [pdf, other]

Title: Changed paradigm of fast magnetic reconnection

Authors: Allen H Boozer

Comments: arXiv admin note: text overlap with arXiv:1407.6069

Subjects: Plasma Physics (physics.plasm-ph); Solar and Stellar Astrophysics (astro-ph.SR)

Although magnetic reconnection takes place in three-dimensional space, reconnection theory has focused on two-dimensional models for more than sixty years. Well-posed three-dimensional mathematics associated with the theory of fluid mixing provides a predictive and compelling explanation for why fast magnetic reconnection is prevalent---exponentially large variations in the separations between magnetic field lines. The proofs have been simplified to remove any rational reason to maintain a focus on two dimensional models, which fail to represent the mathematical properties of three-dimensional space.

[58]  arXiv:2002.04480 (cross-list from gr-qc) [pdf, ps, other]

Title: Tidal heating of Quantum Black Holes and their imprints on gravitational waves

Authors: Sayak Datta

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

The characteristic difference between a black hole and other exotic compact objects (ECOs) is the presence of the horizon. The horizon of a classical black hole acts as a one-way membrane. Due to this nature, any perturbation on the black hole must satisfy ingoing boundary conditions at the horizon. For an ECO either the horizon is replaced or modified with a surface with non zero reflectivity. This results in a modification of the boundary condition of the perturbation around such systems. In this work, we study how tidal heating of an ECO gets modified due to the presence of a reflective surface and what implication it brings for the gravitational wave observations.

Replacements for Wed, 12 Feb 20

[59]  arXiv:1502.06867 (replaced) [pdf, other]

Title: Rotational spectroscopy as a tool to investigate interactions between vibrational polyads in symmetric top molecules: low-lying states $v_8 \le 2$ of methyl cyanide, CH$_3$CN

Authors: Holger S. P. Müller, Linda R. Brown, Brian J. Drouin, John C. Pearson, Isabelle Kleiner, Robert L. Sams, Keeyoon Sung, Matthias H. Ordu, Frank Lewen

Comments: 20 pages, astract abbreviated; appeared in Journal of Molecular Spectroscopy; CDMS links updated; dipole values in Table 10 corrected (were correct in text)

Journal-ref: J. Mol. Spectrosc. 312 (2015) 22-37

Subjects: Astrophysics of Galaxies (astro-ph.GA); Earth and Planetary Astrophysics (astro-ph.EP); Atomic and Molecular Clusters (physics.atm-clus); Chemical Physics (physics.chem-ph)

[60]  arXiv:1809.07834 (replaced) [pdf, other]

Title: The role of mass, equation of state and superfluid reservoir in large pulsar glitches

Authors: Alessandro Montoli, Marco Antonelli, Pierre Pizzochero

Comments: 11 pages, 6 figures

Journal-ref: Monthly Notices of the Royal Astronomical Society, Volume 492, Issue 4, March 2020, Pages 4837-4846

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

[61]  arXiv:1809.08078 (replaced) [pdf, other]

Title: The Harvard Science Research Mentoring Program

Authors: Or Graur

Comments: Revised version, after several rounds of refereeing

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

[62]  arXiv:1903.03118 (replaced) [pdf, other]

Title: New substellar discoveries from Kepler and K2: Is there a brown dwarf desert?

Authors: Theron Carmichael, David Latham, Andrew Vanderburg

Comments: 15 pages, 6 figures, 11 tables, accepted to AJ

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

[63]  arXiv:1904.00199 (replaced) [pdf, other]

Title: Fuzzy Euclidean wormholes in the inflationary universe

Authors: Pisin Chen, Daeho Ro, Dong-han Yeom

Comments: 14 pages, 8 figures

Journal-ref: Phys.Dark Univ. 28 (2020) 100492

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

[64]  arXiv:1905.09836 (replaced) [pdf, other]

Title: Misalignment & Co.: (Pseudo-)scalar and vector dark matter with curvature couplings

Authors: Gonzalo Alonso Álvarez, Joerg Jaeckel, Thomas Hugle

Comments: 25 pages, 8 figures. References updated and discussion of vector longitudinal modes expanded

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

[65]  arXiv:1906.05772 (replaced) [pdf, other]

Title: A Tip for Landscape Riders: Multi-Field Inflation Can Fulfill the Swampland Distance Conjecture

Authors: Rafael Bravo, Gonzalo A. Palma, Simon Riquelme

Comments: JCAP version. We added a new section discussing non-Gaussianities, along with a new figure. Several minor drafting changes were also made

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

[66]  arXiv:1906.06352 (replaced) [pdf, other]

Title: Oscillons and Dark Matter

Authors: Jan Olle, Oriol Pujolas, Fabrizio Rompineve

Comments: 42 pages, 12 figures. v2: references added, further minor additions in the text

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

[67]  arXiv:1907.00207 (replaced) [pdf, other]

Title: hammurabi X: Simulating Galactic Synchrotron Emission with Random Magnetic Fields

Authors: Jiaxin Wang (1), Tess R. Jaffe (2), Torsten A. Enßlin (3), Piero Ullio (1), Shamik Ghosh (4), Larissa Santos (5) ((1) SISSA, (2) UMD, (3) MPA, (4) USTC, (5) Yangzhou U.)

Comments: 25 pages, 18 figures, Accepted by ApJS with joint JOSS publication at this https URL, the numerical package can be found at this https URL or this https URL

Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Astrophysics of Galaxies (astro-ph.GA)

[68]  arXiv:1907.08298 (replaced) [pdf, other]

Title: MaxiMask and MaxiTrack: two new tools for identifying contaminants in astronomical images using convolutional neural networks

Authors: Maxime Paillassa, Emmanuel Bertin, Hervé Bouy

Comments: 25 pages, 14 figures, accepted in A&A journal, this https URL

Journal-ref: A&A 634, A48 (2020)

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

[69]  arXiv:1907.10112 (replaced) [pdf, other]

Title: Einstein-scalar-Gauss-Bonnet black holes: Analytical approximation for the metric and applications to calculations of shadows

Authors: Roman A. Konoplya, Thomas Pappas, Alexander Zhidenko

Comments: 20 pages, 7 figures, 1 ancillary Mathematica(R) notebook, version accepted for publication in Phys. Rev. D

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

[70]  arXiv:1908.10355 (replaced) [pdf, other]

Title: Probing up-down quark matter via gravitational waves

Authors: Chen Zhang

Comments: Published version. Typo fixed

Journal-ref: Phys.Rev.D 101, 043003 (2020)

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

[71]  arXiv:1908.11170 (replaced) [pdf, other]

Title: A guide to LIGO-Virgo detector noise and extraction of transient gravitational-wave signals

Authors: The LIGO Scientific Collaboration, the Virgo Collaboration: B. P. Abbott, R. Abbott, T. D. Abbott, S. Abraham, F. Acernese, K. Ackley, C. Adams, V. B. Adya, C. Affeldt, M. Agathos, K. Agatsuma, N. Aggarwal, O. D. Aguiar, L. Aiello, A. Ain, P. Ajith, T. Alford, G. Allen, A. Allocca, M. A. Aloy, P. A. Altin, A. Amato, A. Ananyeva, S. B. Anderson, W. G. Anderson, S. V. Angelova, S. Antier, S. Appert, K. Arai, M. C. Araya, J. S. Areeda, M. Arène, N. Arnaud, 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, P. T. Baker, F. Baldaccini, G. Ballardin, S. W. Ballmer, S. Banagiri, J. C. Barayoga, S. E. Barclay, B. C. Barish, D. Barker, K. Barkett, S. Barnum, et al. (1076 additional authors not shown)

Journal-ref: B P Abbott et al 2020 Class. Quantum Grav. 37 055002

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

[72]  arXiv:1909.01400 (replaced) [pdf, other]

Title: Quasar X-ray and UV flux, baryon acoustic oscillation, and Hubble parameter measurement constraints on cosmological model parameters

Authors: Narayan Khadka, Bharat Ratra

Comments: 14 pages, 12 figures

Journal-ref: Mon.Not.Roy.Astron.Soc. 492 (2020) no.3, 4456

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

[73]  arXiv:1909.07402 (replaced) [pdf, other]

Title: The maximum accretion rate of hot gas in dark matter halos

Authors: Jonathan Stern, Drummond Fielding, Claude-André Faucher-Giguère, Eliot Quataert

Comments: 19 pages, 12 figures, accepted to MNRAS

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

[74]  arXiv:1909.11470 (replaced) [pdf, other]

Title: Stability of Axion Dark Matter-Photon Conversion

Authors: Emi Masaki, Arata Aoki, Jiro Soda

Comments: 29 pages, 5 figures, published version

Journal-ref: Phys. Rev. D 101, 043505 (2020)

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

[75]  arXiv:1910.01088 (replaced) [pdf, other]

Title: Dark energy and inflation invoked in CCGG by locally contorted space-time

Authors: David Vasak, Johannes Kirsch, Juergen Struckmeier

Comments: Update based on an improved numerical analysis and differentiation of results. 23 pages + 3 appendices, 38 figures, 2 tables

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

[76]  arXiv:1910.09099 (replaced) [pdf, other]

Title: Log-dependent slope of scalar induced gravitational waves in the infrared regions

Authors: Chen Yuan, Zu-Cheng Chen, Qing-Guo Huang

Comments: 7 pages, 2 figures; typo corrected and more discussion added

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

[77]  arXiv:1911.03717 (replaced) [pdf, other]

Title: Geometric properties of galactic discs with clumpy episodes

Authors: Leandro Beraldo e Silva, Victor P. Debattista, Tigran Khachaturyants, David Nidever

Comments: 11 pages, 12 figures; Updated to published (MNRAS) version - inclusion of extra references and minor changes suggested by the referee

Journal-ref: MNRAS, 2020, 492, 4716

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

[78]  arXiv:1911.09991 (replaced) [pdf, other]

Title: Planetary Nebulae seen by TESS: Results and discovery of new binary central star candidates from Cycle 1

Authors: A. Aller, J. Lillo-Box, D. Jones, L. F. Miranda, S. Barceló Forteza

Comments: Accepted for publication in A&A, 16 pages, 7 figures, 4 tables + 1 Appendix

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

[79]  arXiv:1911.11142 (replaced) [pdf, other]

Title: GW170817A as a Hierarchical Black Hole Merger

Authors: V. Gayathri, I. Bartos, Z. Haiman, S. Klimenko, B. Kocsis, S. Marka, Y. Yang

Comments: 6 pages, 3 figures

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

[80]  arXiv:1911.11526 (replaced) [pdf, other]

Title: Accelerated orbital decay of supermassive black hole binaries in merging nuclear star clusters

Authors: Go Ogiya, Oliver Hahn, Chiara M. F. Mingarelli, Marta Volonteri

Comments: 13 pages, 8 figures, 3 tables and appendices, accepted for publication in MNRAS

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

[81]  arXiv:1911.11959 (replaced) [pdf, other]

Title: Characterising the Structure of Halo Merger Trees Using a Single Parameter: The Tree Entropy

Authors: Danail Obreschkow, Pascal J. Elahi, Claudia del P. Lagos, Rhys J. J. Poulton, Aaron D. Ludlow

Comments: 20 pages, 18 figures

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

[82]  arXiv:1912.10125 (replaced) [pdf, other]

Title: Unlocking Galactic Wolf-Rayet stars with $\textit{Gaia}$ DR2 I: Distances and absolute magnitudes

Authors: Gemma Rate, Paul A. Crowther

Comments: Amended section 3.3, table 4, table 5 and table 6 based on corrected Av to AK conversion. Minor updates to figures, WR/O ratio and WR stars with reliable results. 19 pages, 15 figures. Additional appendices updated (57 pages, 5 figures). To be published in MNRAS

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

[83]  arXiv:1912.11453 (replaced) [pdf, other]

Title: Dark matter with excitable levels

Authors: Andrew J. Wren

Comments: 25 pages, 11 figures, 2 tables. V2 has minor improvements. Mathematica and Python code available at this https URL

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

[84]  arXiv:2001.02681 (replaced) [pdf, other]

Title: Detecting Interstellar Objects Through Stellar Occultations

Authors: Amir Siraj, Abraham Loeb

Comments: 5 pages, 4 figures, 1 table; accepted for publication in ApJL

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

[85]  arXiv:2001.03633 (replaced) [pdf, other]

Title: The Cosmological Heavy Ion Collider: Fast Thermalization after Cosmic Inflation

Authors: Evan McDonough

Comments: 7 pages. v2: references added

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)

[86]  arXiv:2001.04479 (replaced) [pdf, other]

Title: A panchromatic spatially-resolved analysis of nearby galaxies -- I. Sub-kpc scale Main Sequence in grand-design spirals

Authors: A. Enia, G. Rodighiero, L. Morselli, V. Casasola, S. Bianchi, L. Rodriguez-Munoz, C. Mancini, A. Renzini, P. Popesso, P. Cassata, M. Negrello, A. Franceschini

Comments: 21 pages, 15 figures. Accepted for publication in MNRAS

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

[87]  arXiv:2001.07036 (replaced) [pdf, other]

Title: Formation of plasmoid chains and fast magnetic reconnection during nonlinear evolution of the tilt instability

Authors: Hubert Baty

Comments: Oral contribution from the 17th European Fusion Theory Conference

Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Plasma Physics (physics.plasm-ph); Space Physics (physics.space-ph)

[88]  arXiv:2001.08316 (replaced) [pdf, other]

Title: Constraining the $^{22}$Ne($α$,$γ$)$^{26}$Mg and $^{22}$Ne($α$,n)$^{25}$Mg reaction rates using sub-Coulomb $α$-transfer reactions

Authors: H. Jayatissa, G.V. Rogachev, V.Z. Goldberg, E. Koshchiy, G. Christian, J. Hooker, S. Ota, B.T. Roeder, A. Saastamoinen, O. Trippella, S. Upadhyayula, E. Uberseder

Comments: 7 pages, 3 figures, 2 tables

Journal-ref: Phys. Lett. B, 802 (2020) 135267

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

[89]  arXiv:2002.00982 (replaced) [pdf, other]

Title: Global alignments of parsec-scale AGN radio jets and their polarization planes

Authors: D. Blinov, C. Casadio, N. Mandarakas, E. Angelakis

Comments: 8 pages, 9 figures, accepted by Astronomy and Astrophysics

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

[90]  arXiv:2002.01858 (replaced) [pdf, other]

Title: Observational and theoretical constraints on the formation and early evolution of the first dust grains in galaxies at 5 < z < 10

Authors: D. Burgarella (1), A. Nanni (1), H. Hirashita (2), P. Theule (1), A. K. Inoue (3,4), T. T. Takeuchi (5) ((1) Aix Marseille Univ, CNRS, CNES, LAM (2) Institute of Astronomy and Astrophysics, Academia Sinica, Astronomy-Mathematics Building, AS/NTU (3) Department of Physics, School of Advanced Science and Engineering, Faculty of Science and Engineering, Waseda University (4) Waseda Research Institute for Science and Engineering, Faculty of Science and Engineering, Waseda University (5) Division of Particle and Astrophysical Science, Nagoya University)

Comments: Paper accepted for publication in section 4. Extragalactic astronomy of Astronomy and Astrophysics (Feb. 2020). Correction typo in caption of Fig. 1

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

[91]  arXiv:2002.02166 (replaced) [pdf, other]

Title: The Bimodal Distribution in Exoplanet Radii: Considering Varying Core Compositions and $\rm H_{2}$ Envelop Sizes

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

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

[92]  arXiv:2002.02267 (replaced) [pdf, other]

Title: Measuring black hole masses from tidal disruption events and testing the $M_{\rm BH}-σ_*$ relation

Authors: Z.Q. Zhou (PKU), F.K. Liu (PKU, KIAA), S. Komossa (MPIfR), R. Cao (PKU), L.C. Ho (KIAA, PKU), Xian Chen (PKU, KIAA), Shuo Li (NAOC, PKU)

Comments: 39 pages, 12 figures, submitted to ApJ on 2019 December 15

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

[93]  arXiv:2002.03086 (replaced) [pdf, ps, other]

Title: Impact of an Active Sgr A* on the Synthesis of Water and Organic Molecules Throughout the Milky Way

Authors: Chang Liu (PKU), Xian Chen (PKU), Fujun Du (PMO)

Comments: 18 pages, 8 figures, submitted

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

[94]  arXiv:2002.03525 (replaced) [pdf, other]

Title: Crystal Defects: A Portal To Dark Matter Detection

Authors: Fedja Kadribasic, Nader Mirabolfathi, Kai Nordlund, Flyura Djurabekova

Subjects: Instrumentation and Detectors (physics.ins-det); Cosmology and Nongalactic Astrophysics (astro-ph.CO); Materials Science (cond-mat.mtrl-sci); High Energy Physics - Experiment (hep-ex)

[95]  arXiv:2002.03623 (replaced) [pdf, other]

Title: Radiation hydrodynamics in simulations of the solar atmosphere

Authors: Jorrit Leenaarts

Comments: Accepted for publication in Living Reviews in Solar Physics

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

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