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New submissions for Thu, 16 Apr 20

[1]  arXiv:2004.06723 [pdf, other]

Title: NICER-NuSTAR Observations of the Neutron Star Low-Mass X-ray Binary 4U 1735-44

Authors: R. M. Ludlam, E. M. Cackett, J. A. García, J. M. Miller, P. M. Bult, T. E. Strohmayer, S. Guillot, G. K. Jaisawal, C. Malacaria, A. C. Fabian, C. B. Markwardt

Comments: Accepted for publication in ApJ, 8 pages, 1 table, 5 figures

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

We report on the first simultaneous $NICER$ and $NuSTAR$ observations of the neutron star (NS) low-mass X-ray binary 4U 1735$-$44, obtained in 2018 August. The source was at a luminosity of $\sim1.8~(D/5.6\ \mathrm{kpc})^{2}\times10^{37}$ ergs s$^{-1}$ in the $0.4-30$ keV band. We account for the continuum emission with two different continuum descriptions that have been used to model the source previously. Despite the choice in continuum model, the combined passband reveals a broad Fe K line indicative of reflection in the spectrum. In order to account for the reflection spectrum we utilize a modified version of the reflection model RELXILL that is tailored for thermal emission from accreting NSs. Alternatively, we also use the reflection convolution model of RFXCONV to model the reflected emission that would arise from a Comptonized thermal component for comparison. We determine that the innermost region of the accretion disk extends close to the innermost stable circular orbit ($R_{\mathrm{ISCO}}$) at the 90% confidence level regardless of reflection model. Moreover, the current flux calibration of $NICER$ is within 5% of the $NuSTAR$/FPMA(B).

[2]  arXiv:2004.06724 [pdf, other]

Title: Simulations of the Milky Way's central molecular zone -- I. Gas dynamics

Authors: Robin G. Tress, Mattia C. Sormani, Simon C.O. Glover, Ralf S. Klessen, Cara D. Battersby, Paul C. Clark, H Perry Hatchfield, Rowan J. Smith

Comments: 32 pages, 32 figures, submitted to MNRAS. A version with higher-resolution figures can be downloaded from the following link: this http URL Movies of the simulations can be found at the following link: this http URL

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

We use hydrodynamical simulations to study the Milky Way's central molecular zone (CMZ), i.e. the star-forming nuclear ring at Galactocentric radii $R\lesssim200$ pc. The simulations comprise the gas flow in a Milky Way barred potential out to $R=5$ kpc, which is necessary in order to capture the large-scale environment in which the CMZ is embedded and with which it is strongly interacting through the bar-driven inflow. The simulations also include a non-equilibrium time-dependent chemical network, gas self-gravity, and a sub-grid model for star formation and supernova feedback, all while reaching sub-parsec resolution in the densest regions. Our main findings are as follows: (1) The distinction between inner ($R\lesssim120$ pc) and outer ($120\lesssim R\lesssim450$ pc) CMZ that is sometimes proposed in the literature is unnecessary. Instead, the CMZ is best described as single structure, namely a star-forming ring with outer radius $R\simeq 200$ pc which is interacting directly with the dust lanes that mediate the bar-driven inflow. (2) This accretion can induce a significant tilt of the CMZ out of the plane. A tilted CMZ might provide an alternative explanation to the $\infty$-shaped structure identified in Herschel data by Molinari et al. 2011. (3) The bar in our simulation efficiently drives an inflow from the Galactic disc ($R\simeq 3$ kpc) down to the CMZ ($R\simeq200$ pc) of the order of $1\rm\,M_\odot\,yr^{-1}$, consistent with observational determinations. (4) Self-gravity and supernovae feedback can drive an inflow from the CMZ inwards towards the circumnuclear disc of the order of $\sim0.03\,\rm M_\odot\,yr^{-1}$. (5) We give a new interpretation for the 3D placement of the 20 and 50 km s$^{-1}$ clouds, according to which they are close ($R\lesssim30$ pc) to the Galactic centre, but are also connected to the larger-scale streams at $R\gtrsim100$ pc.

[3]  arXiv:2004.06725 [pdf, other]

Title: A Habitable-Zone Earth-Sized Planet Rescued from False Positive Status

Authors: Andrew Vanderburg, Pamela Rowden, Steve Bryson, Jeffrey Coughlin, Natalie Batalha, Karen A. Collins, David W. Latham, Susan E. Mullally, Knicole D. Colón, Chris Henze, Chelsea X. Huang, Samuel N. Quinn

Comments: 11 pages, 3 figures, 1 table. Accepted for publication in ApJL

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

We report the discovery of an Earth-sized planet in the habitable zone of a low-mass star called Kepler-1649. The planet, Kepler-1649 c, is 1.06$^{+0.15}_{-0.10}$ times the size of Earth and transits its 0.1977 +/- 0.0051 Msun mid M-dwarf host star every 19.5 days. It receives 74 +/- 3 % the incident flux of Earth, giving it an equilibrium temperature of 234 +/- 20K and placing it firmly inside the circumstellar habitable zone. Kepler-1649 also hosts a previously-known inner planet that orbits every 8.7 days and is roughly equivalent to Venus in size and incident flux. Kepler-1649 c was originally classified as a false positive by the Kepler pipeline, but was rescued as part of a systematic visual inspection of all automatically dispositioned Kepler false positives. This discovery highlights the value of human inspection of planet candidates even as automated techniques improve, and hints that terrestrial planets around mid to late M-dwarfs may be more common than those around more massive stars.

[4]  arXiv:2004.06728 [pdf, other]

Title: The Massive and Distant Clusters of WISE Survey. IX. SZ effect Verification with the Atacama Compact Array: Localisation and Cluster Analysis

Authors: Luca Di Mascolo, Tony Mroczkowski, Eugene Churazov, Emily Moravec, Mark Brodwin, Anthony Gonzalez, Bandon B. Decker, Peter R. M. Eisenhardt, Spencer A. Stanford, Daniel Stern, Rashid Sunyaev, Dominika Wylezalek

Comments: 19 pages (including appendices), 14 figures, and 4 tables; resubmitted to A&A after minor revision

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

The Massive and Distant Clusters of WISE Survey (MaDCoWS) provides a catalogue of high-redshift ($0.7\lesssim z\lesssim 1.5$) infrared-selected galaxy clusters. However, the verification of the ionised intracluster medium, indicative of a collapsed and nearly virialised system, is made challenging by the high redshifts of the sample members. The main goal of this work is to test the capabilities of the Atacama Compact (Morita) Array (ACA) Band 3 observations, centred about 97.5 GHz, to provide robust validation of cluster detections via the thermal Sunyaev-Zeldovich effect. Using a pilot sample that comprises ten MaDCoWS galaxy clusters, accessible to ACA and representative of the median sample richness, we infer the masses of the selected galaxy clusters and respective detection significance by means of a Bayesian analysis of the interferometric data. Our test of the "Verification with the ACA - Localisation and Cluster Analysis" (VACA LoCA) programme demonstrates that the ACA can robustly confirm the presence of the virialised intracluster medium in galaxy clusters previously identified in full-sky surveys. In particular, we obtained a significant detection of the SZ effect for seven out of the ten VACA LoCA clusters. We note that this result is independent of the assumed pressure profile. However, the limited angular dynamic range of the ACA in Band 3 alone, short observational integration times, and possible contamination from unresolved sources limit the detailed characterisation of the cluster properties and the inference of the cluster masses within scales appropriate for the robust calibration of mass-richness scaling relations.

[5]  arXiv:2004.06729 [pdf, other]

Title: Searching for General Binary Inspirals with Gravitational Waves

Authors: Horng Sheng Chia, Thomas D. P. Edwards

Comments: 16 pages, 5 figures

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

We study whether binary black hole template banks can be used to search for the gravitational waves emitted by general binary coalescences. To recover binary signals from noisy data, matched-filtering techniques are typically required. This is especially true for low-mass systems, with total mass $M \lesssim 10 \, M_\odot$, which can inspiral in the LIGO and Virgo frequency bands for thousands of cycles. In this paper, we focus on the detectability of low-mass binary systems whose individual components can have large spin-induced quadrupole moments and small compactness. The quadrupole contributes to the phase evolution of the waveform whereas the compactness affects the merger frequency of the binary. We find that binary black hole templates (with dimensionless quadrupole $\kappa=1$) cannot be reliably used to search for objects with large quadrupoles ($\kappa\gtrsim 20$) over a wide range of parameter space. This is especially true if the general object is highly spinning and has a larger mass than its binary companion. A binary that consists of objects with small compactness could merge in the LIGO and Virgo frequency bands, thereby reducing its accumulated signal-to-noise ratio during the inspiraling regime. Template banks which include these more general waveforms must therefore be constructed. These extended banks would allow us to realistically search for the existence of new astrophysical and beyond the Standard Model compact objects.

[6]  arXiv:2004.06730 [pdf, other]

Title: Radio linear polarization of GRB afterglows: Instrumental Systematics in ALMA observations of GRB 171205A

Authors: Tanmoy Laskar, Charles L. H. Hull, Paulo Cortes

Comments: 10 pages, 8 figures. Accepted for publication in ApJ

Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Instrumentation and Methods for Astrophysics (astro-ph.IM)

Polarization measurements of gamma-ray burst (GRB) afterglows are a promising means of probing the structure, geometry, and magnetic composition of relativistic GRB jets. However, a precise treatment of instrumental calibration is vital for a robust physical interpretation of polarization data, requiring tests of and validations against potential instrumental systematics. We illustrate this with ALMA Band 3 (97.5 GHz) observations of GRB 171205A taken $\approx5.19$ days after the burst, where a detection of linear polarization was recently claimed. We describe a series of tests for evaluating the stability of polarization measurements with ALMA. Using these tests to re-analyze and evaluate the archival ALMA data, we uncover systematics in the polarization calibration at the $\approx0.09\%$ level. We derive a 3$\sigma$ upper limit on the linearly polarized intensity of $P<97.2~\mu$Jy, corresponding to an upper limit on the linear fractional polarization of $\Pi_{\rm L}<0.30\%$, in contrast to the previously claimed detection. Our upper limit improves upon existing constraints on the intrinsic polarization of GRB radio afterglows by a factor of 3. We discuss this measurement in the context of constraints on the jet magnetic field geometry. We present a compilation of polarization observations of GRB radio afterglows, and demonstrate that a significant improvement in sensitivity is desirable for eventually detecting signals polarized at the $\approx0.1\%$ level from typical radio afterglows.

[7]  arXiv:2004.06731 [pdf, other]

Title: Simulations of the Milky Way's central molecular zone -- II. Star formation

Authors: Mattia C. Sormani, Robin G. Tress, Simon C.O. Glover, Ralf S. Klessen, Cara D. Battersby, Paul C. Clark, H Perry Hatchfield, Rowan J. Smith

Comments: 15 pages, 15 figures, submitted to MNRAS. Movies of the simulations can be found at the following link: this http URL

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

The Milky Way's central molecular zone (CMZ), i.e. the star-forming nuclear ring at $R\lesssim200$ pc, has emerged in recent years as a unique laboratory for the study star formation. In this paper we use the simulations presented in Tress et al. 2020 to investigate star formation in the CMZ. The simulations include the gas flow in the whole inner disc ($R\leq5$ kpc) of the Milky Way, which allows us to assess how the large-scale environment affects the formation of stars in the CMZ. We comfortably reach sub-parsec resolution, which allows us to resolve individual molecular clouds. Our main findings are as follows. (1) By studying the spatial and temporal distribution of stars formed along the CMZ ring, we find that most of the star formation happens downstream of the apocentres, consistent with the "pearls-on-a-string" scenario. (2) Our simulations do not support the notion that an absolute evolutionary timeline of star formation triggered by pericentre passage can be identified as gas clouds orbit in the CMZ ring. (3) Within the timescale of our simulation ($\sim100$ Myr), the depletion time of the CMZ is constant within a factor of $\sim2$. This suggests that variations in the star formation rate are primarily driven by variations in the mass of the CMZ, caused for example by changes in the bar-driven inflow rate, AGN feedback, or other external events, and not by variations in the depletion time. (4) We study the trajectories of newly born stars in our simulations. We find several examples that have age, line-of-sight velocity and proper motion velocity compatible with the Arches and Quintuplet clusters. Our simulation suggests that these prominent clusters originate near the collision sites where the bar-driven inflow accretes onto the CMZ, at symmetrical locations with respect to the Galactic centre, and that they have already decoupled from the gas in which they were born.

[8]  arXiv:2004.06732 [pdf, other]

Title: Resolving nearby dust clouds

Authors: R. H. Leike, M. Glatzle, T. A. Enßlin

Subjects: Astrophysics of Galaxies (astro-ph.GA); Computational Physics (physics.comp-ph)

Aims: Mapping the interstellar medium in 3D provides a wealth of insights into its inner working. The Milky Way is the only galaxy, for which a detailed 3D mapping can be achieved in principle. In this paper, we reconstruct the dust density in and around the local super-bubble.
Methods: The combined data from surveys such as Gaia, 2MASS, PANSTARRS, and ALLWISE provide the necessary information to make detailed maps of the interstellar medium in our surrounding. To this end, we use variational inference and Gaussian processes to model the dust extinction density, exploiting its intrinsic correlations.
Results: We reconstruct a highly resolved dust map, showing the nearest dust clouds at a distance of up to 400\,pc with a resolution of 1\,pc.
Conclusions: Our reconstruction provides insights into the structure of the interstellar medium. We compute summary statistics of the spectral index and the 1-point function of the logarithmic dust extinction density, which may constrain simulations of the interstellar medium that achieve similar resolution.

[9]  arXiv:2004.06733 [pdf, other]

Title: Modeling Dark Photon Oscillations in Our Inhomogeneous Universe

Authors: Andrea Caputo, Hongwan Liu, Siddharth Mishra-Sharma, Joshua T. Ruderman

Comments: 22+4 pages, 17 figures

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

A dark photon may kinetically mix with the Standard Model photon, leading to observable cosmological signatures. The mixing is resonantly enhanced when the dark photon mass matches the primordial plasma frequency, which depends sensitively on the underlying spatial distribution of electrons. Crucially, inhomogeneities in this distribution can have a significant impact on the nature of resonant conversions. We develop and describe, for the first time, a general analytic formalism to treat resonant oscillations in the presence of inhomogeneities. Our formalism follows from the theory of level crossings of random fields and only requires knowledge of the one-point probability distribution function (PDF) of the underlying electron number density fluctuations. We validate our formalism using simulations and illustrate the photon-to-dark photon conversion probability for several different choices of PDFs that are used to characterize the low-redshift Universe.

[10]  arXiv:2004.06734 [pdf, other]

Title: Eigengalaxies: describing galaxy morphology using principal components in image space

Authors: Emir Uzeirbegovic, James E. Geach, Sugata Kaviraj

Comments: Submitted to MNRAS, comments welcome

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

We demonstrate how galaxy morphologies can be represented by weighted sums of 'eigengalaxies' and how eigengalaxies can be used in a probabilistic framework to enable principled and simplified approaches in a variety of applications. Eigengalaxies can be derived from a Principal Component Analysis (PCA) of sets of single- or multi-band images. They encode the image space equivalent of basis vectors that can be combined to describe the structural properties of large samples of galaxies in a massively reduced manner. As an illustration, we show how a sample of 10,243 galaxies in the Hubble Space Telescope CANDELS survey, which have visual classifications from Galaxy Zoo, can be represented by just 12 eigengalaxies whilst retaining 96% explained variance. We show how the emphasis of certain eigengalaxy components correspond to visual features (e.g. disc, point source, etc.), and explore the correspondence between combinations of eigengalaxies and features defined in the Galaxy Zoo-CANDELS catalogue. We also describe a probabilistic extension to PCA (PPCA) which enables the eigengalaxy framework to assign probabilities to galaxies and characterise a whole population as a generative distribution. We present four practical applications of the probabilistic eigengalaxy framework that are particularly relevant for the next generation of large imaging surveys: we (i) show how low probability galaxies make for natural candidates for outlier detection (ii) demonstrate how missing data can be predicted (iii) show how a similarity search can be performed on exemplars (iv) demonstrate how unsupervised clustering of objects can be implemented.

[11]  arXiv:2004.06743 [pdf, other]

Title: The ram pressure stripped radio tails of galaxies in the Coma cluster

Authors: Hao Chen, Ming Sun, Masafumi Yagi, Hector Bravo-Alfaro, Elias Brinks, Jeffrey Kenney, Francoise Combes, Suresh Sivanandam, Pavel Jachym, Matteo Fossati, Giuseppe Gavazzi, Alessandro Boselli, Paul Nulsen, Craig Sarazin, Chong Ge, Michitoshi Yoshida, Elke Roediger

Comments: 20 pages, 11 figures, Submitted to MNRAS

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

Previous studies have revealed a population of galaxies in galaxy clusters with ram pressure stripped (RPS) tails of gas and embedded young stars. We observed 1.4 GHz continuum and HI emission with the Very Large Array in its B-configuration in two fields of the Coma cluster to study the radio properties of RPS galaxies. The best continuum sensitivities in the two fields are 6 and 8 $\mu$Jy per 4'' beam respectively, which are 4 and 3 times deeper than those previously published. Radio continuum tails are found in 10 (8 are new) out of 20 RPS galaxies, unambiguously revealing the presence of relativistic electrons and magnetic fields in the stripped tails. Our results also hint that the tail has a steeper spectrum than the galaxy. The 1.4 GHz continuum in the tails is enhanced relative to their H$\alpha$ emission by a factor of $\sim$7 compared to the main bodies of the RPS galaxies. The 1.4 GHz continuum of the RPS galaxies is enhanced relative to their IR emission by a factor of $\sim$2 compared to star-forming galaxies. The ram pressure interaction may enhanced the radio emission of the RPS galaxies, the tails were further enhanced for the stripping. We furthermore present HI detections in three RPS galaxies and upper limits for the other RPS galaxies. The cold gas in D100's stripped tail is dominated by molecular gas, which is likely a consequence of the high ambient pressure. No evidence of radio emission associated with ultra-diffuse galaxies is found in our data.

[12]  arXiv:2004.06779 [pdf, ps, other]

Title: Superparticle Method for Simulating Collisions

Authors: David Nesvorny, Andrew N. Youdin, Raphael Marschall, Derek C. Richardson

Comments: accepted in ApJ

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

For problems in astrophysics, planetary science and beyond, numerical simulations are often limited to simulating fewer particles than in the real system. To model collisions, the simulated particles (aka superparticles) need to be inflated to represent a collectively large collisional cross section of real particles. Here we develop a superparticle-based method that replicates the kinetic energy loss during real-world collisions, implement it in an $N$-body code and test it. The tests provide interesting insights into dynamics of self gravitating collisional systems. They show how particle systems evolve over several free fall timescales to form central concentrations and equilibrated outer shells. The superparticle method can be extended to account for the accretional growth of objects during inelastic mergers.

[13]  arXiv:2004.06781 [pdf, ps, other]

Title: Planet-star interactions with precise transit timing. II. The radial-velocity tides and a tighter constraint on the orbital decay rate in the WASP-18 system

Authors: G. Maciejewski, H. A. Knutson, A. W. Howard, H. Isaacson, E. Fernandez-Lajus, R. P. Di Sisto, C. Migaszewski

Comments: Accepted for publication in Acta Astronomica

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

From its discovery, the WASP-18 system with its massive transiting planet on a tight orbit was identified as a unique laboratory for studies on tidal planet-star interactions. In an analysis of Doppler data, which include five new measurements obtained with the HIRES/Keck-I instrument between 2012 and 2018, we show that the radial velocity signal of the photosphere following the planetary tidal potential can be distilled for the host star. Its amplitude is in agreement with both theoretical predictions of the equilibrium tide approximation and an ellipsoidal modulation observed in an orbital phase curve. Assuming a circular orbit, we refine system parameters using photometric time series from TESS. With a new ground-based photometric observation, we extend the span of transit timing observations to 28 years in order to probe the rate of the orbital period shortening. Since we found no departure from a constant-period model, we conclude that the modified tidal quality parameter of the host star must be greater than 3.9x10^6 with 95% confidence. This result is in line with conclusions drawn from studies of the population of hot Jupiters, predicting that the efficiency of tidal dissipation is 1 or 2 orders of magnitude weaker. As the WASP-18 system is one of the prime candidates for detection of orbital decay, further timing observations are expected to push the boundaries of our knowledge on stellar interiors.

[14]  arXiv:2004.06802 [pdf, other]

Title: EX Draconis: Using Eclipses to Separate Outside-In and Inside-Out Outbursts

Authors: James M. C. Court, Simone Scaringi, Colin Littlefield, Noel Castro Segura, Knox S. Long, Thomas Maccarone, Diego Altamirano, Nathalie Degenaar, Rudy Wijnands, Tariq Shahbaz, Zhuchang Zhan

Comments: 10 pages, 6 figures

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

We present a study of the eclipses in the accreting white dwarf EX Dra during TESS Cycles 14 and 15. During both of the two outbursts present in this dataset, the eclipses undergo a hysteretic loop in eclipse-depth/out-of-eclipse-flux space. In each case, the direction in which the loops are executed strongly suggests an outburst which is triggered near the inner edge of the accretion disk and propagates outwards. This in turn suggests that the outbursts in EX Dra are 'Inside Out' outbursts; events predicted by previous hydrodynamic studies of dwarf nova accretion disks and confirmed spectroscopically in a number of other accreting white dwarf systems. We therefore propose that the direction of the loop executed in eclipse-depth/out-of-eclipse flux space be used as a test to phenomenologically distinguish between 'inside out' and 'outside in' outbursts in other eclipsing dwarf novae; a reliable and purely photometric test to differentiate between these phenomena.

[15]  arXiv:2004.06808 [pdf]

Title: Concept for the GMT High-Contrast Exoplanet Instrument GMagAO-X and the GMT High-Contrast Phasing Testbed with MagAO-X

Authors: Laird M. Close, Jared R. Males, Alex Hedglen, Antonin Bouchez, Olivier Guyon

Comments: Proc. Adaptive Optics For Extremely Large Telescopes: AO4ELT6, Quebec City, Canada, June 2019. 12 pages 10 figures. arXiv admin note: substantial text overlap with arXiv:1807.04311, arXiv:1807.05070

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

Here we review the current conceptual optical mechanical design of GMagAO-X --the extreme AO (ExAO) system for the Giant Magellan Telescope (GMT). The GMagAO-X tweeter deformable mirror (DM) design is novel in that it uses an optically distributed set of pupils that allows seven commercially available 3000 actuator BMC DMs to work "in parallel" to effectively create an ELT-scale ExAO tweeter DM --with all parts commercially available today. The GMagAO-X "parallel DM" tweeter will have 21,000 actuators to be used at ~2kHz update speeds enabling high-contrast science at ~5 mas separations in the visible and NIR of the spectrum (0.6-1.7 microns). To prove our concept for GMagAO-X several items must be lab tested: the optical/mechanical concept for the parallel DM; phasing of the GMT pupil; and solving the GMT's "isolated island effect" will all be demonstrated on an optical testbed at the University of Arizona. Here we outline the current design for this "GMT High-Contrast Testbed" that has been proposed jointly by GMTO and the University of Arizona which leverages the existing, operational, MagAO-X ExAO instrument to verify our approach to phase sensing and AO control for high-contrast GMT NGS science. We will also highlight how GMagAO-X can be mounted on the auxiliary port of the GMT and so remain gravity invariant. Since it is gravity invariant GMagAO-X can utilize a floating optical table to minimize flexure and NCP vibrations.

[16]  arXiv:2004.06812 [pdf, ps, other]

Title: WIYN Open Cluster Study LXXIX. M48 (NGC 2548) I. Radial Velocities, Rotational Velocities, and Metallicities of Stars in the Open Cluster M48 (NGC 2548)

Authors: Qinghui Sun, Constantine P. Deliyannis, Aaron Steinhauer, Bruce A. Twarog, Barbara J. Anthony-Twarog

Comments: 17 pages, 11 figures, accepted in the Astronomical Journal

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

WIYN/Hydra spectra (R $\sim$ 13,500, signal-to-noise pixel$^{-1}$ = 50-1000) of a 400 $\unicode{x212B}$ region around Li 6708 $\unicode{x212B}$ are used to determine radial and rotational velocities for 287 photometrically selected candidate members of the open cluster M48. The sample ranges from turnoff A stars to late-K dwarfs and eight giants. We combine our $V_{\rm{RAD}}$ measurements and power spectrum analysis with parallax and proper motion data from Gaia DR2 to evaluate membership and multiplicity. We classify 152 stars as single cluster members, 11 as binary members, 16 as members of uncertain multiplicity, 56 as single nonmembers, 28 as single "likely" nonmembers, two as single "likely" members, one as a binary "likely" member, five as binary nonmembers, 10 as "likely" members of uncertain multiplicity, three as nonmembers of uncertain multiplicity, and three as "likely" nonmembers of uncertain multiplicity. From a subsample of 95 single members, we derive $V_{\rm{RAD}}$ = 8.512 $\pm$ 0.087 km s$^{-1}$ ($\sigma_{\mu}$, and $\sigma$ = 0.848 km s$^{-1}$). Using 16 isolated Fe I lines for a subsample of 99 single members (that have $\sigma_{T_{\rm{eff}}}$ $<$ 75 K (from 10 colors from $UBVRI$), $v$ sin $i$ $<$ 25 km s$^{-1}$, and well-behaved Fe I lines), [Fe/H]$_{\rm{M48}}$ = -0.063 $\pm$ 0.007 dex ($\sigma_{\mu}$). [Fe/H] is independent of $T_{\rm{eff}}$ over an unprecedentedly large range of 2500 K. The minimum cluster binary fraction is 11%-21%. M48 exhibits a clear but modest broadening of the main-sequence turnoff, and there is no correlation between color and $v$ sin $i$.

[17]  arXiv:2004.06815 [pdf, other]

Title: Thermodynamic Structure of the Solar Corona: Tomographic Reconstructions and MHD Modeling

Authors: D. G. Lloveras, A. M. Vásquez, F. A. Nuevo, C. Mac Cormack, N. Sachdeva, W. Manchester IV, B. Van der Holst, R. A. Frazin

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

We carry out a study of the global three-dimensional (3D) structure of the electron density and temperature of the quiescent inner solar corona ($r<1.25 R_\odot$) by means of tomographic reconstructions and magnetohydrodynamic simulations. We use differential emission measure tomography (DEMT) and the Alfv\'en Wave Solar Model (AWSoM), in their latest versions. Two target rotations were selected from the solar minimum between solar cycles (SCs) 23 and 24 and the declining phase of SC 24. We report in quantitative detail on the 3D thermodynamic structure of the core and outer layers of the streamer belt, and of the high latitude coronal holes (CH), as revealed by the DEMT analysis. We report on the presence of two types of structures within the streamer belt, loops with temperature decreasing/increasing with height (dubbed down/up loops), as reported first in previous DEMT studies. We also estimate the heating energy flux required at the coronal base to keep these structures stable, found to be or order $10^5 erg\, cm^{-2} s^{-1}$, consistently with previous DEMT and spectroscopic studies. We discuss how these findings are consistent with coronal dissipation of Alfv\'en waves. We compare the 3D results of DEMT and AWSoM in distinct magnetic structures. We show that the agreement between the products of both techniques is the best so far, with an overall agreement $\lesssim 20\%$, depending on the target rotation and the specific coronal region. In its current implementation the ASWsoM model can not reproduce down loops though. Also, in the source region of the fast and slow components of the solar wind, the electron density of the AWSoM model increases with latitude, opposite to the trend observed in DEMT reconstructions.

[18]  arXiv:2004.06829 [pdf, other]

Title: Common Envelope Evolution on the Asymptotic Giant Branch: Unbinding within a Decade?

Authors: Luke Chamandy, Eric G. Blackman, Adam Frank, Jonathan Carroll-Nellenback

Comments: 11 pages, 12 figures, submitted to MNRAS

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

Common envelope (CE) evolution is a critical but still poorly understood progenitor phase of many high-energy astrophysical phenomena. Although 3D global hydrodynamic CE simulations have become more common in recent years, those involving an asymptotic giant branch (AGB) primary are scarce, due to the high computational cost from the larger dynamical range compared to red giant branch (RGB) primaries. But CE evolution with AGB progenitors is desirable to simulate because such events are the likely progenitors of most bi-polar planetary nebulae (PNe), and prominent observational testing grounds for CE physics. Here we present a high resolution global simulation of CE evolution involving an AGB primary and $1\,\mathrm{M}_\odot$ secondary, evolved for $20$ orbital revolutions. During the last $16$ of these orbits, the envelope unbinds at an almost constant rate of about $0.1$-$0.2\,\mathrm{M}_\odot\,\mathrm{yr}^{-1}$. If this rate were maintained, the envelope would be unbound in less than $10\,\mathrm{yr}$. We compare this run with a previous run that used an RGB phase primary evolved from the same $2\,\mathrm{M}_\odot$ main sequence star to assess the influence of the evolutionary state of the primary. When scaled appropriately, the two runs are quite similar, but with some important differences.

[19]  arXiv:2004.06837 [pdf, ps, other]

Title: Fast degradation of the circular flare ribbon on 2014 August 24

Authors: Q. M. Zhang, S. H. Yang, T. Li, Y. J. Hou, Y. Li

Comments: 4 pages, 5 figures, accepted for publication in A&A Letters

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

The separation and elongation motions of solar flare ribbons have extensively been investigated. The degradation and disappearance of ribbons have rarely been explored. In this paper, we report our multiwavelength observations of a C5.5 circular-ribbon flare associated with two jets (jet1 and jet2) on 2014 August 24, focusing on the fast degradation of the outer circular ribbon (CR). The flare, consisting of a short inner ribbon (IR) and outer CR, was triggered by the eruption of a minifilament. The brightness of IR and outer CR reached their maxima simultaneously at $\sim$04:58 UT in all AIA wavelengths. Subsequently, the short eastern part of CR faded out quickly in 1600 {\AA} but gradually in EUV wavelengths. The long western part of CR degraded in the counterclockwise direction and experienced a deceleration. The degradation was distinctly divided into two phases: phase I with faster apparent speeds (58$-$69 km s$^{-1}$) and phase II with slower apparent speeds (29$-$35 km s$^{-1}$). The second phase stopped at $\sim$05:10 UT when the western CR totally disappeared. Besides the outward propagation of jet1, the jet spire experienced untwisting motion in the counterclockwise direction during 04:55$-$05:00 UT. We conclude that the event can be explained by the breakout jet model. The coherent brightenings of the IR and CR at $\sim$04:58 UT may result from the impulsive interchange reconnection near the null point, whereas sub-Alfv\'{e}nic slipping motion of the western CR in the counterclockwise direction indicates the occurrence of slipping magnetic reconnection. Another possible explanation of the quick disappearance of the hot loops connecting to the western CR is that they are simply reconnected sequentially without the need for significant slippage after the null point reconnection.

[20]  arXiv:2004.06841 [pdf, other]

Title: On the Energy Coupling Efficiency of AGN Outbursts in Galaxy Clusters

Authors: Xiaodong Duan, Fulai Guo

Comments: 19 pages, 11 figures, submitted to ApJ

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

Active galactic nucleus (AGN) jets are believed to be important in solving the cooling flow problem in the intracluster medium (ICM), while the detailed mechanism is still in debate. Here we present a systematic study on the energy coupling efficiency $\eta_{\rm cp}$, the fraction of AGN jet energy transferred to the ICM. We first estimate the values of $\eta_{\rm cp}$ analytically in two extreme cases, which are further confirmed and extended with a parameter study of spherical outbursts in a uniform medium using hydrodynamic simulations. We find that $\eta_{\rm cp}$ increases from $\sim 0.4$ for a weak isobaric injection to $\gtrsim 0.8$ for a powerful point injection. For any given outburst energy, we find two characteristic outburst powers that separate these two extreme cases. We then investigate the energy coupling efficiency of AGN jet outbursts in a realistic ICM with hydrodynamic simulations, finding that jet outbursts are intrinsically different from spherical outbursts. For both powerful and weak jet outbursts, $\eta_{\rm cp}$ is typically around $0.7-0.9$, partly due to the non-spherical nature of jet outbursts, which produce backflows emanating from the hotspots, significantly enhancing the ejecta-ICM interaction. While for powerful outbursts a dominant fraction of the energy transferred from the jet to the ICM is dissipated by shocks, shock dissipation only accounts for $\lesssim 30\%$ of the injected jet energy for weak outbursts. While both powerful and weak outbursts could efficiently heat cooling flows, powerful thermal-energy-dominated jets are most effective in delaying the onset of the central cooling catastrophe.

[21]  arXiv:2004.06844 [pdf, other]

Title: New limits on neutrino decay from the Glashow resonance of high-energy cosmic neutrinos

Authors: Mauricio Bustamante (Bohr Inst. and DARK Cosmology Ctr.)

Comments: 5 pages, 2 figures, technical appendices

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

Discovering neutrino decay would be strong evidence of physics beyond the Standard Model. Presently, there are only lax lower limits on the lifetime $\tau$ of neutrinos, of $\tau/m \sim 10^{-3}$ s eV$^{-1}$ or worse, where $m$ is the unknown neutrino mass. High-energy cosmic neutrinos, with TeV-PeV energies, offer superior sensitivity to decay due to their cosmological-scale baselines. To tap into it, we employ a promising method, recently proposed, that uses the Glashow resonance $\bar{\nu}_e + e \to W$, triggered by $\bar{\nu}_e$ of 6.3 PeV, to test decay with only a handful of detected events. If most of the $\nu_1$ and $\nu_2$ decay into $\nu_3$ en route to Earth, no Glashow resonance would occur in neutrino telescopes, because the remaining $\nu_3$ have only a tiny electron-flavor content. We turn this around and use the recent first detection of a Glashow resonance candidate in IceCube to place new lower limits on the lifetimes of $\nu_1$ and $\nu_2$. For $\nu_2$, our limit is the current best. For $\nu_1$, our limit is close to the current best and, with the imminent detection of a second Glashow resonance, will vastly surpass it.

[22]  arXiv:2004.06845 [pdf, other]

Title: A Dual-Band Radio Observation of FRB 121102 with the Deep Space Network and the Detection of Multiple Bursts

Authors: Walid A. Majid, Aaron B. Pearlman, Kenzie Nimmo, Jason W. T. Hessels, Thomas A. Prince, Charles J. Naudet, Jonathon Kocz, Shinji Horiuchi

Comments: 8 pages, 3 figures, Submitted for publication in ApJL on 2020 April 13

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

The spectra of repeating fast radio bursts (FRBs) are complex and time-variable, sometimes peaking within the observing band and showing a fractional emission bandwidth of about 10-30%. These spectral features may provide insight into the emission mechanism of repeating fast radio bursts, or they could possibly be explained by extrinsic propagation effects in the local environment. Broadband observations can better quantify this behavior and help to distinguish between intrinsic and extrinsic effects. We present results from a simultaneous 2.25 and 8.36 GHz observation of the repeating FRB 121102 using the 70 m Deep Space Network (DSN) radio telescope, DSS-43. During the 5.7 hr continuous observing session, we detected 6 bursts from FRB 121102, which were visible in the 2.25 GHz frequency band. However, none of these bursts were detected in the 8.36 GHz band, despite the larger bandwidth and greater sensitivity in the higher-frequency band. This effect is not explainable by Galactic scintillation and, along with previous multi-band experiments, clearly demonstrates that apparent burst activity depends strongly on the radio frequency band that is being observed.

[23]  arXiv:2004.06859 [pdf, other]

Title: No consistent atmospheric absorption detected for the ultra-hot Jupiter WASP-189 b

Authors: P. Wilson Cauley, Evgenya Shkolnik, Ilya Ilyin, Klaus G. Strassmeier, Seth Redfield, Adam G. Jensen

Comments: Accepted as a research note to RNAAS. 3 pages, 1 figure

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

We observed a partial transit of the ultra-hot Jupiter WASP-189 b with PEPSI on the LBT. We detect a highly variable transit signal in multiple atomic transitions, including H-alpha, Fe I, and Mg I. The signal is not consistent with a transiting planetary atmosphere. We suggest instead that the in-transit signal is due to an inhomogeneous stellar surface. Our observations demonstrate the lack of a highly extended atmosphere in common optical atomic tracers. Although WASP-189 is very bright, atmospheric characterization of the planet will be difficult due to the small transit depth and apparently compact atmosphere.

[24]  arXiv:2004.06914 [pdf, other]

Title: Mean plane of the Kuiper belt beyond 50 AU in the presence of Planet 9

Authors: Jian Li, Zhihong Jeff Xia

Comments: 7 pages, 9 figures, Accepted for publication on Astronomy and Astrophysics

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

Context. A recent observational census of Kuiper belt objects (KBOs) has unveiled anomalous orbital structures. This has led to the hypothesis that an additional $\sim5-10~m_{\oplus}$ planet exists. This planet, known as Planet 9, occupies an eccentric and inclined orbit at hundreds of astronomical units. However, the KBOs under consideration have the largest known semimajor axes at $a>250$ AU; thus they are very difficult to detect.//
Aims. In the context of the proposed Planet 9, we aim to measure the mean plane of the Kuiper belt at $a>50$ AU. In a comparison of the expected and observed mean planes, some constraints would be put on the mass and orbit of this undiscovered planet.
Methods. We adopted and developed the theoretical approach of Volk & Malhotra (2017) to the relative angle $\delta$ between the expected mean plane of the Kuiper belt and the invariable plane determined by the eight known planets. Numerical simulations were constructed to validate our theoretical approach. Then similar to Volk & Malhotra (2017), we derived the angle $\delta$ for the real observed KBOs with $100<a<200$ AU, and the measurement uncertainties were also estimated. Finally, for comparison, maps of the theoretically expected $\delta$ were created for different combinations of possible Planet 9 parameters.
Results. The expected mean plane of the Kuiper belt nearly coincides with the said invariable plane interior to $a=90$ AU. But these two planes deviate noticeably from each other at $a>100$ AU owing to the presence of Planet 9 because the relative angle $\delta$ could be as large as $\sim10^{\circ}$. Using the $1\sigma$ upper limit of $\delta<5^{\circ}$ deduced from real KBO samples as a constraint, we present the most probable parameters of Planet 9.

[25]  arXiv:2004.06926 [pdf, other]

Title: A Cold and Diffuse Giant Molecular Filament in the Region of $l=41^\circ$, $b=-1^\circ$

Authors: Liang-Hao Lin, Hong-Chi Wang, Yang Su, Chong Li, Ji Yang

Comments: 17 pages, 14 figures. Accepted for publication in Research in Astronomy and Astrophysics

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

Data of $^{12}$CO/$^{13}$CO/C$^{18}$O $J=1\to0$ emission toward the Galactic plane region of $l=35^\circ$ to $45^\circ$ and $b= -5^\circ$ to $+5^\circ$ are available with the Milky Way Imaging Scroll Painting (MWISP) project. Using the data, we found a giant molecular filament (GMF) around $l\approx38\sim42^\circ$, $b\approx-3.5\sim0^\circ$, $V_{LSR} \approx 27 \sim 40$ km~s$^{-1}$, named the GMF MWISP G041-01. At a distance of 1.7 kpc, the GMF is about 160 pc long. With a median excitation temperature about 7.5 K and a median column density about $10^{21}$ cm$^{-2}$, this GMF is very cold and very diffuse compared to known GMFs. Using the morphology in the data cube, the GMF is divided into four components among which three show filamentary structure. Masses of the components are $ 10^3 \sim 10^4 M_\odot$, with a total mass for the whole filament being about $7\times10^4 M_\odot$ from the LTE method. $^{13}$CO cores inside each component are searched. Virial parameters are about 2.5 for these cores and have a power-law index of -0.34 against the mass. The mass fraction of dense cores traced by $^{13}$CO to the diffuse clouds traced by $^{12}$CO are about 7% for all components of the GMF. We found signatures of possible large scale filament-filament collision in the GMF.

[26]  arXiv:2004.06936 [pdf, other]

Title: RES-NOVA: A revolutionary neutrino observatory based on archaeological lead

Authors: Luca Pattavina, Nahuel Ferreiro Iachellini, Irene Tamborra

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

We present the RES-NOVA project which will hunt neutrinos from core-collapse supernovae (SN) via coherent elastic neutrino-nucleus scattering (CE$\nu$NS) using an array of archaeological lead (Pb) based cryogenic detectors. The high CE$\nu$NS cross-section on Pb and the ultra-high radiopurity of archaeological Pb enable the operation of a high statistics experiment equally sensitive to all neutrino flavors with reduced detector dimensions and easy scalability to larger detector volumes. RES-NOVA will be operating in three phases with increasing detector volumes: (60 cm)$^3$, (140 cm)$^3$, and ultimately 15$\times$(140 cm)$^3$. It will be sensitive to SN bursts up to Andromeda with 5$\sigma$ sensitivity with already existing technology and will have excellent energy resolution with $1$ keV threshold. Within our Galaxy, it will be possible to discriminate core-collapse SNe from black hole forming collapses with no ambiguity even in the first phase of RES-NOVA. The average neutrino energy of all flavors, the SN neutrino light curve, and the total energy emitted in neutrinos will be constrained with a precision of few $\%$ in the final detector phase. RES-NOVA will potentially detect the first flavor-blind neutrinos from the diffuse SN neutrino background with an exposure of $620$ ton$^{-1}$ yr$^{-1}$. The RES-NOVA project has the potential to lay down the foundations for a new generation of neutrino telescopes, while relying on a very simple technological setup.

[27]  arXiv:2004.06974 [pdf, ps, other]

Title: Connecting measurements of solar and stellar brightness variations

Authors: N.-E. Nèmec (1), E. Işık (2, 1), A. I. Shapiro (1), S. K. Solanki (1, 3), N. A. Krivova (1), Y. Unruh (4) ((1) Max-Planck-Institut für Sonnensystemforschung, (2) Dept. of Computer Science, Turkish-German University, (3) School of Space Research, Kyung Hee University, (4) Imperial College, Astrophysics Group)

Comments: 9 pages, 9 figures, accepted for publication in Astronomy & Astrophysics

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

Comparing solar and stellar brightness variations is hampered by the difference in spectral passbands used in observations as well as by the possible difference in the inclination of their rotation axes from the line of sight. We calculate the rotational variability of the Sun as it would be measured in passbands used for stellar observations. In particular, we consider the filter systems used by the CoRoT, $Kepler$, TESS, and $Gaia$ space missions. We also quantify the effect of the inclination of the rotation axis on the solar rotational variability. We employ the Spectral And Total Irradiance REconstructions (SATIRE) model to calculate solar brightness variations in different filter systems as observed from the ecliptic plane. We then combine the simulations of the surface distribution of the magnetic features at different inclinations using a surface flux transport model (SFTM) with the SATIRE calculations to compute the dependence of the variability on the inclination. For an ecliptic-bound observer, the amplitude of the solar rotational variability, as observed in the total solar irradiance (TSI) is 0.68 mmag (averaged over solar cycles 21-24). We obtained corresponding amplitudes in the $Kepler$ (0.74 mmag), CoRoT (0.73 mmag), TESS (0.62 mmag), $Gaia~ $ (0.74 mmag), $Gaia~ G_{RP}$ (0.62 mmag), and ), $Gaia~ G_{BP}$ (0.86 mmag) passbands. Decreasing the inclination of the rotation axis decreases the rotational variability. For a sample of randomly inclined stars, the variability is on average 15% lower in all filter systems considered in this work. This almost compensates for the difference in the amplitudes of the variability in TSI and $Kepler$ passbands, making the amplitudes derived from the TSI records an ideal representation of the solar rotational variability for comparison to $Kepler$ stars with unknown inclinations.

[28]  arXiv:2004.06978 [pdf, ps, other]

Title: Circular polarisation from inhomogeneous synchrotron sources

Authors: C.-I. Bjornsson

Comments: Accepted to ApJ; 24 pages and 3 appendices

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

Inhomogeneities can influence the polarisation emerging from a synchrotron source. However, it is shown that the frequency distribution of circular polarisation is only marginally affected, although its magnitude may change substantially. This is used to argue that the observed properties of compact radio sources imply a radiating plasma in which the characteristic waves are nearly circular. As a result, restrictions can be put on the low energy part of the energy distribution of the relativistic electrons as well as the presence of electron-positron pairs. It is emphasised that this constrains theoretical modelling of the acceleration process for the relativistic electrons; for example, some of the currently popular scenarios seem to need modifications to become consistent with observations.

[29]  arXiv:2004.06979 [pdf, other]

Title: A Method for Unmasking Incomplete Astronomical Signals: Application to CO Multi-line Imaging of Nearby Galaxies Project

Authors: Suchetha Cooray (1), Tsutomu T. Takeuchi (1 and 2), Moe Yoda (1), Kazuo Sorai (3 and 4) ((1) Nagoya University, Japan, (2) Institute of Statistical Mathematics, Japan, (3) Hokkaido University, Japan, (4) University of Tsukuba, Japan)

Comments: 15 pages, 8 figures, accepted for publication in PASJ

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

Photometric surveys have provided incredible amounts of astronomical information in the form of images. However, astronomical images often contain artifacts that can critically hinder scientific analysis by misrepresenting intensities or contaminating catalogs as artificial objects. These affected pixels need to be masked and dealt with in any data reduction pipeline. In this paper, we present a flexible, iterative algorithm to recover (unmask) astronomical images where some pixels are lacking. We demonstrate the application of the method on some intensity calibration source images in CO Multi-line Imaging of Nearby Galaxies (COMING) Project conducted using the 45m telescope at Nobeyama Radio Observatory (NRO). The proposed algorithm restored artifacts due to a detector error in the intensity calibration source images. The restored images were used to calibrate 11 out of 147 observed galaxy maps in the survey. The tests show that the algorithm can restore measured intensities at sub 1% error even for noisy images (SNR = 2.4), despite lacking a significant part of the image. We present the formulation of the reconstruction algorithm, discuss its possibilities and limitations for extensions to other astronomical signals and the results of the COMING application.

[30]  arXiv:2004.06992 [pdf, other]

Title: Investigating the morphology of the supernova remnant G349.7+00.2 in the medium with a density gradient

Authors: Jing-Wen Yan, Chun-Yan Lu, Lu Wen, Huan Yu, Jun Fang

Comments: 8 pages, 5 figures

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

G349.7 + 00.2 is a young Galactic supernova remnant (SNR) with a mushroom morphology in radio and X-rays, and it has been detected across the entire electromagnetic spectrum from radio to high energy $\gamma$-rays. Moreover, the remnant is interacting with a molecular cloud based on the observations in the radio and infrared band. The reason for the formation of the periphery and the dynamical evolution of the remnant are investigated using 3D hydrodynamical (HD) simulations. Under the assumption that the supernova ejecta is evolved in the medium with a density gradient, the shell is composed of two hemispheres with different radiuses, and the smaller hemisphere is in relatively dense media. The resulting periphery of remnant is consistent with detected ones, and it can be concluded that the peculiar periphery of G349.7+00.2 can be reproduced as the remnants interacting with the medium with a density gradient.

[31]  arXiv:2004.06995 [pdf, other]

Title: Model-independent energy budget of cosmological first-order phase transitions

Authors: Felix Giese, Thomas Konstandin, Jorinde van de Vis

Comments: 24 pages, 2 figures

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

We study the energy budget of a first-order cosmological phase transition, which is an important factor in the prediction of the resulting gravitational wave spectrum. Formerly, this analysis was based mostly on simplified models as for example the bag equation of state. Here, we present a model-independent approach that is exact up to the temperature dependence of the speed of sound in the broken phase. We find that the only relevant quantities that enter in the hydrodynamic analysis are the speed of sound in the broken phase and a linear combination of the energy and pressure differences between the two phases which we call pseudotrace (normalized to the enthalpy in the broken phase). The pseudotrace quantifies the strength of the phase transition and yields the conventional trace of the energy-momentum tensor for a relativistic plasma (with speed of sound squared of one third). We study this approach in several realistic models of the phase transition and also provide a code snippet that can be used to determine the efficiency coefficient for a given phase transition strength and speed of sound. It turns out that our approach is accurate to the percent level for moderately strong phase transitions, while former approaches give at best the right order of magnitude.

[32]  arXiv:2004.07021 [pdf, other]

Title: Higher-Order Spectra of Weak Lensing Convergence Maps in Parameterized Theories of Modified Gravity

Authors: D. Munshi, J. D. McEwen

Comments: 22 pages, 5 figures

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

We compute the low-$\ell$ limit of the family of higher-order spectra for projected (2D) weak lensing convergence maps. In this limit, these spectra are computed to an arbitrary order using {\em tree-level} perturbative calculations. We use the flat-sky approximation and Eulerian perturbative results based on a generating function approach. We test these results for the lower-order members of this family, i.e. the skew- and kurt-spectra against state-of-the-art simulated all-sky weak lensing convergence maps and find our results to be in very good agreement. We also show how these spectra can be computed in the presence of a realistic sky-mask and Gaussian noise. We generalize these results to three-dimensions (3D) and compute the {\em equal-time} higher-order spectra. These results will be valuable in analyzing higher-order statistics from future all-sky weak lensing surveys such as the {\em Euclid} survey at low-$\ell$ modes. As illustrative examples, we compute these statistics in the context of the {\em Horndeski} and {\em Beyond Horndeski} theories of modified gravity. They will be especially useful in constraining theories such as the Gleyzes-Langlois-Piazza-Vernizzi (GLPV) theories and Degenerate Higher-Order Scalar-Tensor (DHOST) theories as well as the commonly used normal-branch of Dvali-Gabadadze-Porrati (nDGP) model, clustering quintessence models, and scenarios with massive neutrinos.

[33]  arXiv:2004.07074 [pdf, ps, other]

Title: H I absorption towards radio Active Galactic Nuclei of different accretion modes

Authors: Yogesh Chandola, D.J. Saikia, Di Li

Comments: 19 (16+3) pages, 9 figures, accepted for publication in MNRAS

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

We present results of H I absorption experiment done using the Giant Metrewave Radio Telescope (GMRT) towards 27 low- and intermediate-luminosity ($P_{\rm 1.4 GHz}$ $\sim$10$^{23}$-10$^{26}$ W Hz$^{-1}$) radio active galactic nuclei (AGN), classified as either low excitation radio galaxies (LERGs) or high excitation radio galaxies (HERGs) and with WISE colour W2[4.6 $\mu$m]$-$W3[12 $\mu$m]$>$ 2. We report H I absorption detection towards seven radio AGNs, six of which are new. Combined with other sources from literature classified as LERGs or HERGs, we confirm our earlier result that compact radio AGNs with WISE colour W2$-$W3 $>$2 have higher detection rates compared to those with W2$-$W3 $<$2. We find that H I absorption detection rate is higher for HERGs (37.0$^{+15.8}_{-11.5}$ per cent) compared to LERGs (22.0$^{+3.9}_{-3.4}$ per cent), mainly due to a larger fraction of HERGs being gas and dust rich with a younger stellar population compared to LERGs. However, for similar compact radio structures and host galaxies with WISE colours W2$-$W3$>$2, we don't find any significant difference in detection rates of two types of AGNs implying detection of H I gas may not necessarily mean high excitation mode AGN. We further analysed the kinematics towards these sources. We find that while LERGs show a wide range in the shift of centroid velocities ($\sim$ $-$479 to $+$356 km s$^{-1}$) relative to the optical systemic velocity, most of the HERGs have centroid velocity shift less than 200 km s$^{-1}$, possibly due to differences in jet-interstellar medium interaction.

[34]  arXiv:2004.07075 [pdf, ps, other]

Title: Determination of magnetic field strength on the event horizon of supermassive black holes in active galactic nuclei

Authors: M.Yu. Piotrovich, A.G. Mikhailov, S.D. Buliga, T.M. Natsvlishvili

Comments: 8 pages, 8 figures

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

We estimated the magnetic field strength at the event horizon for a sample of supermassive black holes (SMBHs) in active galactic nuclei (AGNs). Our estimates were made using the values of the inclination angles of the accretion disk to the line of sight, that we obtained previously from spectropolarimetric observations in the visible spectrum. We also used published values of full width at half maximum (FWHM) of spectral line $H_\beta$ from broad line region, masses of SMBHs and luminosity of AGNs at 5100 angstrom. In addition we used literature data on the spins of SMBHs obtained from their X-ray spectra. Our estimates showed that the magnetic field strength at the event horizon of the majority of SMBHs in AGNs ranges from several to tens of kG and have mean values of about $10^4$G. At the same time, for individual objects, the fields are significantly larger - of the order of hundreds kG or even 1 MG.

[35]  arXiv:2004.07092 [pdf, other]

Title: SDSS J211852.96-073227.5: the first non-local interacting late-type intermediate Seyfert galaxy with relativistic jets

Authors: Emilia Järvelä, Marco Berton, Stefano Ciroi, Enrico Congiu, Anne Lähteenmäki, Francesco Di Mille

Comments: 6 pages, 6 figures, accepted for publication in A&A

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

The existence of a relation between relativistic jets in active galactic nuclei (AGN) and the morphology of their host galaxies has often been suggested. In particular, relativistic jets may be commonly connected with merging events. We present here for the first time a detailed spectroscopic and morphological analysis of a Seyfert galaxy, SDSS J211852.96-073227.5, at $z = 0.26$. This source has been previously classified as a gamma-ray emitting narrow-line Seyfert 1 galaxy. We reobserved it with the 6.5m Clay Telescope, and these new, high-quality spectroscopic data revealed that it is actually an intermediate type Seyfert galaxy. Furthermore, modelling of the $Ks$-band near-infrared images obtained with the 6.5m Baade Telescope suggests that the AGN is hosted by a late-type galaxy in an interacting system, strenghtening the suggested connection between galaxy interactions and relativistic jets.

[36]  arXiv:2004.07134 [pdf, other]

Title: Atmospheric stability and collapse on tidally locked rocky planets

Authors: Pierre Auclair-Desrotour, Kevin Heng

Comments: 27 pages, 15 figures, accepted for publication in Astronomy & Astrophysics

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

Over large timescales, a terrestrial planet may be driven towards spin-orbit synchronous rotation by tidal forces. In this particular configuration, the planet exhibits permanent dayside and nightside, which may induce strong day-night temperature gradients. The nightside temperature depends on the efficiency of the day-night heat redistribution and determines the stability of the atmosphere against collapse. To better constrain the atmospheric stability, climate, and surface conditions of rocky planets located in the habitable zone of their host star, it is thus crucial to understand the complex mechanism of heat redistribution. Building on early works and assuming dry thermodynamics, we developed a hierarchy of analytic models taking into account the coupling between radiative transfer, dayside convection, and large-scale atmospheric circulation in the case of slowly rotating planets. There are two types of these models: a zero-dimensional two-layer approach and a two-column radiative-convective-subsiding-upwelling (RCSU) model. They yield analytical solutions and scaling laws characterising the dependence of the collapse pressure on physical features, which are compared to the results obtained by early works using 3D global climate models (GCMs). The analytical theory captures (i) the dependence of temperatures on atmospheric opacities and scattering in the shortwave and in the longwave, (ii) the behaviour of the collapse pressure observed in GCM simulations at low stellar fluxes that are due to the non-linear dependence of the atmospheric opacity on the longwave optical depth at the planet's surface, (iii) the increase of stability generated by dayside sensible heating, and (iv) the decrease of stability induced by the increase of the planet size.

[37]  arXiv:2004.07185 [pdf, other]

Title: The Flux Distribution of Sgr A*

Authors: The GRAVITY Collaboration: R. Abuter, A. Amorim, M Bauboeck, H. Bonnet, W. Brandner, V. Cardoso, Y. Clenet, P.T. de Zeeuw, J. Dexter, A. Eckart, F. Eisenhauer, N.M. Förster Schreiber, P. Garcia, F. Gao, E. Gendron, R. Genzel, S. Gillessen, M. Habibi, X. Haubois, T. Henning, S. Hippler, M. Horrobin, L. Jocou, A. Jimenez-Rosales, L. Jochum, L. Jocou, A. Kaufer, P. Kervella, S. Lacour, V. Lapeyrère, J.-B. Le Bouquin, P. Léna, M. Nowak, T. Ott, T. Paumard, K. Perraut 5, G. Perrin, O. Pfuhl, G. Ponti, G. Rodriguez Coira, J. Shangguan, S. Scheithauer, J. Stadler, O. Straub, C. Straubmeier, E. Sturm, L.J. Tacconi, K.R.W. Tristram, F. Vincent, S.D. von Fellenberg, I. Waisberg, F. Widmann, E. Wieprecht, E. Wiezorrek, J. Woillez, S. Yazici, G. Zins

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

The Galactic Center black hole Sagittarius A* is a variable NIR source that exhibits bright flux excursions called flares. The low-flux density turnover of the flux distribution is below the sensitivity of current single-aperture telescopes. We use the unprecedented resolution of the GRAVITY instrument at the VLTI. Our light curves are unconfused, overcoming the confusion limit of previous photometric studies. We analyze the light curves using standard statistical methods and obtain the flux distribution. We find that the flux distribution of SgrA* turns over at a median flux density of (1.1\pm0.3)mJy. We measure the percentiles of the flux distribution and use them to constrain the NIR K-band SED. Furthermore, we find that the flux distribution is intrinsically right-skewed to higher flux density in log space. Flux densities below 0.1mJy are hardly ever observed. In consequence, a single powerlaw or lognormal distribution does not suffice to describe the observed flux distribution in its entirety. However, if one takes into account a power law component at high flux densities, a lognormal distribution can describe the lower end of the observed flux distribution. We confirm the RMS-flux relation for Sgr~A* and find it to be linear for all flux densities in our observation. We conclude that Sgr~A* has two states: the bulk of the emission is generated in a lognormal process with a well-defined median flux density and this quiescent emission is supplemented by sporadic flares that create the observed power law extension of the flux distribution.

[38]  arXiv:2004.07187 [pdf, other]

Title: Detection of the Schwarzschild precession in the orbit of the star S2 near the Galactic centre massive black hole

Authors: GRAVITY Collaboration: R. Abuter, A. Amorim, M. Bauboeck, J.P. Berger, H. Bonnet, W. Brandner, V. Cardoso, Y. Clenet, P.T. de Zeeuw, J. Dexter, A. Eckart, F. Eisenhauer, N.M. Foerster Schreiber, P. Garcia, F. Gao, E. Gendron, R. Genzel, S. Gillessen, M. Habibi, X. Haubois, T. Henning, S. Hippler, M. Horrobin, A. Jimenez-Rosales, L. Jochum, L. Jocou, A. Kaufer, P. Kervella, S. Lacour, V. Lapeyrere, J.-B. Le Bouquin, P. Lena, M. Nowak, T. Ott, T. Paumard, K. Perraut, G. Perrin, O. Pfuhl, G. Rodriguez-Coira, J. Shangguan, S. Scheithauer, J. Stadler, O. Straub, C. Straubmeier, E. Sturm, L.J. Tacconi, F. Vincent, S. von Fellenberg, I. Waisberg, F. Widmann, E. Wieprecht, E. Wiezorrek, J. Woillez, S. Yazici, G. Zins

Comments: accepted to A&A

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

The star S2 orbiting the compact radio source Sgr A* is a precision probe of the gravitational field around the closest massive black hole (candidate). Over the last 2.7 decades we have monitored the star's radial velocity and motion on the sky, mainly with the SINFONI and NACO adaptive optics (AO) instruments on the ESO VLT, and since 2017, with the four-telescope interferometric beam combiner instrument GRAVITY. In this paper we report the first detection of the General Relativity (GR) Schwarzschild Precession (SP) in S2's orbit. Owing to its highly elliptical orbit (e = 0.88), S2's SP is mainly a kink between the pre-and post-pericentre directions of motion ~ +- 1 year around pericentre passage, relative to the corresponding Kepler orbit. The superb 2017-2019 astrometry of GRAVITY defines the pericentre passage and outgoing direction. The incoming direction is anchored by 118 NACO-AO measurements of S2's position in the infrared reference frame, with an additional 75 direct measurements of the S2-Sgr A* separation during bright states ('flares') of Sgr A*. Our 14-parameter model fits for the distance, central mass, the position and motion of the reference frame of the AO astrometry relative to the mass, the six parameters of the orbit, as well as a dimensionless parameter f_SP for the SP (f_SP = 0 for Newton and 1 for GR). From data up to the end of 2019 we robustly detect the SP of S2, del phi = 12' per orbital period. From posterior fitting and MCMC Bayesian analysis with different weighting schemes and bootstrapping we find f_SP = 1.10 +- 0.19. The S2 data are fully consistent with GR. Any extended mass inside S2's orbit cannot exceed ~ 0.1% of the central mass. Any compact third mass inside the central arcsecond must be less than about 1000 M_sun.

[39]  arXiv:2004.07196 [pdf, ps, other]

Title: Orientation and accretion in a representative sample of active galactic nuclei

Authors: Jessie Runnoe, Todd Boroson

Comments: 28 pages, 10 figures, 6 tables, submitted to ApJ

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

We highlight a representative sample of active galactic nuclei selected independent of orientation. The defining characteristic of the selection is sophisticated matching between the $0.1<z<0.6$ Sloan Digital Sky Survey quasars from the Seventh Data Release to the Westerbork Northern Sky Survey at 325 MHz and the subsequent application of a total radio luminosity cut. The resulting sample is complete down to the limiting luminosity and unbiased by orientation. Compared to orientation samples in the literature this approach yields less bias with redshift, relatively more lobe-dominated sources including those with radio lobes and no visible core, and a distribution of radio core dominance that is consistent with expectations from a uniform distribution of inclinations with solid angle. We measure properties of the optical spectra, and use the sample to investigate the orientation dependence of the velocity width of the broad H$\beta$ emission line. We recover the known orientation dependence, but the sharp envelope of previous studies where only edge-on sources display the broadest lines, is absent. Scatter in this diagram is not attributable solely to black hole mass, Eddington ratio, or contamination in the sample from compact steep spectrum sources. A physical framework for quasar beaming and a disk-like broad-line region can describe the representative sample when it is expanded to include additional parameters, in particular jet properties and the broad-line region velocity field. These points serve to illustrate the critical role of sample selection in the interpretation of observable properties as indicators of physical parameters of quasar central engines.

[40]  arXiv:2004.07218 [pdf, other]

Title: Tidal fragmentation as the origin of 1I/2017 U1 ('Oumuamua)

Authors: Yun Zhang, Douglas N. C. Lin

Comments: 33 pages, 3 figures, Published in Nature Astronomy on 13 April 2020 for associated supplementary files, see this http URL

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

The first discovered interstellar object (ISO), `Oumuamua (1I/2017 U1) shows a dry and rocky surface, an unusually elongated short-to-long axis ratio $c/a \lesssim 1/6$, a low velocity relative to the local standard of rest ($\sim 10$ km s$^{-1}$), non-gravitational accelerations, and tumbles on a few hours timescale. The inferred number density ($\sim 3.5 \times 10^{13} - 2 \times 10^{15}$ pc$^{-3}$) for a population of asteroidal ISOs outnumbers cometary ISOs by $\geq 10^3$, in contrast to the much lower ratio ($\lesssim 10^{-2}$) of rocky/icy Kuiper belt objects. Although some scenarios can cause the ejection of asteroidal ISOs, a unified formation theory has yet to comprehensively link all `Oumuamua's puzzling characteristics and to account for the population. Here we show by numerical simulations that `Oumuamua-like ISOs can be prolifically produced through extensive tidal fragmentation and ejected during close encounters of their volatile-rich parent bodies with their host stars. Material strength enhanced by the intensive heating during periastron passages enables the emergence of extremely elongated triaxial ISOs with shape $c/a \lesssim 1/10$, sizes $a \sim 100$ m, and rocky surfaces. Although volatiles with low sublimation temperature (such as CO) are concurrently depleted, H$_2$O buried under surfaces is preserved in these ISOs, providing an outgassing source without measurable cometary activities for `Oumuamua's non-gravitational accelerations during its passage through the inner Solar System. We infer that the progenitors of `Oumuamua-like ISOs may be km-sized long-period comets from Oort clouds, km-sized residual planetesimals from debris disks, or planet-size bodies at a few AU, orbiting around low-mass main-sequence stars or white dwarfs. These provide abundant reservoirs to account for `Oumuamua's occurrence rate.

[41]  arXiv:2004.07230 [pdf, other]

Title: Polar planets around highly eccentric binaries are the most stable

Authors: Cheng Chen, Stephen H. Lubow, Rebecca G. Martin

Comments: 11 pages, 7 figures

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

We study the orbital stability of a non-zero mass, close-in circular orbit planet around an eccentric orbit binary for various initial values of the binary eccentricity, binary mass fraction, planet mass, planet semi--major axis, and planet inclination by means of numerical simulations that cover $5 \times 10^4$ binary orbits. For small binary eccentricity, the stable orbits that extend closest to the binary (most stable orbits) are nearly retrograde and circulating. For high binary eccentricity, the most stable orbits are highly inclined and librate near the so-called generalised polar orbit which is a stationary orbit that is fixed in the frame of the binary orbit. For more extreme mass ratio binaries, there is a greater variation in the size of the stability region (defined by initial orbital radius and inclination) with planet mass and initial inclination, especially for low binary eccentricity. For low binary eccentricity, inclined planet orbits may be unstable even at large orbital radii (separation $> 5 \,a_{\rm b}$). The escape time for an unstable planet is generally shorter around an equal mass binary compared with an unequal mass binary. Our results have implications for circumbinary planet formation and evolution and will be helpful for understanding future circumbinary planet observations.

[42]  arXiv:2004.07239 [pdf, other]

Title: Pebble-driven Planet Formation around Very Low-mass Stars and Brown Dwarfs

Authors: Beibei Liu, Michiel Lambrechts, Anders Johansen, Ilaria Pascucci, Thomas Henning

Comments: 12 pages, 8 figures, accepted in A&A

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

We conduct a pebble-driven planet population synthesis study to investigate the formation of planets around very low-mass stars and brown dwarfs, in the (sub)stellar mass range between $0.01 \ M_{\odot}$ and $0.1 \ M_{\odot}$. Based on the extrapolation of numerical simulations of planetesimal formation by the streaming instability, we obtain the characteristic mass of the planetesimals and the initial masses of the protoplanets (largest bodies from the planetesimal size distributions), in either the early self-gravitating phase or the later non-self-gravitating phase of the protoplanetary disk evolution. We find that the initial protoplanets form with masses that increase with host mass, orbital distance and decrease with disk age. Around late M-dwarfs of $0.1 \ M_{\odot}$, these protoplanets can grow up to Earth-mass planets by pebble accretion. However, around brown dwarfs of $0.01 \ M_{\odot}$, planets do not grow larger than Mars mass when the initial protoplanets are born early in self-gravitating disks, and their growth stalls at around $0.01$ Earth-mass when they are born late in non-self-gravitating disks. Around these low mass stars and brown dwarfs, we find no channel for gas giant planet formation because the solid cores remain too small. When the initial protoplanets form only at the water-ice line, the final planets typically have ${\gtrsim} 15\%$ water mass fraction. Alternatively, when the initial protoplanets form log-uniformly distributed over the entire protoplanetary disk, the final planets are either very water-rich (water mass fraction ${\gtrsim}15\%$) or entirely rocky (water mass fraction ${\lesssim}5\%$).

[43]  arXiv:2004.07240 [pdf, other]

Title: Detection of anisotropic galaxy assembly bias in BOSS DR12

Authors: Andrej Obuljen, Will J. Percival, Neal Dalal

Comments: 15 pages, 11 figures. Comments welcome

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

We present evidence of anisotropic galaxy assembly bias in the Baryon Oscillation Spectroscopic Survey Data Release 12 galaxy sample at a level exceeding $5\sigma$. We use measurements of the line-of-sight velocity dispersion $\sigma_\star$ and stellar mass $M_\star$ to perform a simple split into subsamples of galaxies. We show that the amplitude of the monopole and quadrupole moments of the power spectrum depend differently on $\sigma_\star$ and $M_\star$, allowing us to split the galaxy sample into subsets with matching monopoles but significantly different quadrupoles on all scales. Combining data from the LOWZ and CMASS NGC galaxy samples, we find $>5\sigma$ evidence for anisotropic bias on scales $k<0.15\,h\,\rm{Mpc}^{-1}$. We also examine splits using other observed properties. For galaxy samples split using $M_\star$ and projected size $R_0$, we find no significant evidence of anisotropic bias. Galaxy samples selected using additional properties exhibit strongly varying degrees of anisotropic assembly bias, depending on which combination of properties is used to split into subsets. This may explain why previous searches for this effect using the Fundamental Plane found inconsistent results. We conclude that any selection of a galaxy sample that depends on $\sigma_\star$ can give biased and incorrect Redshift Space Distortion measurements.

Cross-lists for Thu, 16 Apr 20

[44]  arXiv:2004.06276 (cross-list from gr-qc) [pdf, other]

Title: Quantum Black Hole Seismology II: Applications to Astrophysical Black Holes

Authors: Naritaka Oshita, Daichi Tsuna, Niayesh Afshordi

Comments: 14 pages, 14 figures. NO and DT equally contributed to this work. To be submitted to a journal this weekend, comments welcome

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

With the advent of gravitational wave astronomy, searching for gravitational wave echoes from black holes (BHs) is becoming an interesting probe of their quantum nature near their horizons. Newborn BHs may be strong emitters of echoes, as they accompany large perturbations in the surrounding spacetime upon formation. Utilizing the Quantum Black Hole Seismology framework (Oshita et al. 2020), we study the expected echoes upon BH formation resulting from neutron star mergers and failed supernovae. For BH remnants from neutron star mergers, we evaluate the consistency of these models with the recent claim on the existence of echoes following the neutron star merger event GW170817. We find that the claimed echoes in GW170817, if real, suggest that overtones contribute a significant amount of energy in the ringdown of the remnant BH. We finally discuss the detectability of echoes from failed supernovae by second and third-generation gravitational wave detectors, and find that current (future) detectors constrain physical reflectivity models for events occurring within a few Mpc (a few x 10 Mpc). Detecting such echo signals may significantly constrain the maximum mass and equation of state of neutron stars.

[45]  arXiv:2004.06771 (cross-list from hep-ph) [pdf, other]

Title: Possibility of bottom-catalyzed matter genesis near to primordial QGP hadronization

Authors: Cheng Tao Yang, Johann Rafelski

Comments: 7 pages, 4 figures

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

We study bottom flavor abundance in the early Universe near to a temperature $T_\mathrm{H}\simeq150\,\mathrm{MeV}$, the condition for hadronization of deconfined quark-gluon plasma (QGP). We show bottom flavor abundance nonequilibrium lasting microseconds. In our study we use that in both QGP, and the hadronic gas phase (HG) $b$ and $\bar b$ quarks near $T_\mathrm{H}$ are bound in B-mesons and antimesons subject to $CP$ violating weak decays. A coincident non-equilibrium abundance of bottom flavor can lead to matter genesis at required strength: a) The specific thermal yield per entropy is $n_b^{th}/\sigma=10^{-10}\sim10^{-13}$. b) Considering time scales, millions of cycles of B-meson decays, and $b\bar b$-pair recreation processes occur.

[46]  arXiv:2004.06884 (cross-list from gr-qc) [pdf, other]

Title: Growth of matter fluctuations in $f(R,T)$ Gravity

Authors: Snehasish Bhattacharjee

Comments: 8 pages with 2 figures

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

In this work, I present for the first time the analysis concerning the growth of matter fluctuations in the framework of $f(R,T)$ modified gravity where I presume $f(R,T) = R + \lambda T$, where $R$ denote the Ricci scalar, $T$ the trace of energy momentum tensor and $\lambda$ a constant. I first solve the Friedman equations for the Hubble parameter $H(z)$ and then employ it in the equation of matter density fluctuations $\delta(z)$ to solve for $\delta(z)$ and the growth rate $f(z)$. Next, I proceed to show the behavior of $f(z)$ and $\delta(z)$ with redshift for some values of $\lambda$ with observational constraints. Finally, following the prescription of \cite{growft41}, I present an analytical expression for the growth index $\gamma$ which is redshift independent and reduces approximately to the conventional $\Lambda$CDM model for $\lambda=0$.

[47]  arXiv:2004.06984 (cross-list from physics.ins-det) [pdf, other]

Title: Broadband Electrical Action Sensing Techniques with conducting wires for low-mass dark matter axion detection

Authors: Michael Edmund Tobar, Ben T. McAllister, Maxim Goryachev

Subjects: Instrumentation and Detectors (physics.ins-det); Instrumentation and Methods for Astrophysics (astro-ph.IM); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Experiment (hep-ex)

Due to the inverse Primakoff effect it has been shown that when axions interact with a DC magnetic B-field the resulting electrical action will produce an AC electromotive force which oscillates at the Compton frequency of the axion, and may be modeled as an oscillating effective impressed magnetic current boundary source. We use this result to calculate the sensitivity of new experiments to low-mass axions using the quasi-static technique. First, we calculate the current induced in an electric dipole antenna (straight conducting wire) when the DC B-field is spatially constant. We show that an experiment based on the dipole antenna is not as sensitive as current low-mass experiments. Following this we extend the topology by making use of the full extent of the spatially varying DC B-field. This extension is achieved by transforming the 1D conducting wire to a 2D winding, to fully link the effective magnetic current boundary source and thus couple to the full axion induced electrical action. In this case the conductor becomes a coil winding where the voltage induced across the winding increases proportionally to the number of windings. We investigate two different topologies: The 1st uses a single winding, and couples to the effective short circuit current generated in the winding, which is read out using a sensitive low impedance SQUID amplifier: The 2nd uses multiple windings, with every turn effectively increasing the the voltage output proportional to the winding number. The read out of this configuration is optimised by implementing a cryogenic low-noise high input impedance voltage amplifier. The end result is a new Broadband Electrical Action Sensing Techniques with orders of magnitude improved sensitivity, which is linearly proportional to the axion photon coupling and capable of detecting QCD dark matter axions.

[48]  arXiv:2004.07026 (cross-list from nucl-th) [pdf, other]

Title: The possibility of twin star solutions in a model based on lattice QCD thermodynamics

Authors: P. Jakobus, A. Motornenko, R. O. Gomes, J. Steinheimer, H. Stoecker

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

The properties of compact stars and in particular the existence of twin star solutions are investigated within an effective model that is constrained by lattice QCD thermodynamics. The model is modified at large baryon densities to incorporate a large variety of scenarios of first order phase transitions to a phase of deconfined quarks. This is achieved by matching two different variants of the bag model equation of state, in order to estimate the role of the Bag model parameters on the appearance of a second family of neutron stars. The produced sequences of neutron stars are compared with modern constrains on stellar masses, radii, and tidal deformability from astrophysical observations and gravitational wave analyses. It is found that most of the possible scenarios disfavor a strong phase transition to quark matter and do not support the conjecture of a second family of neutron stars.

[49]  arXiv:2004.07199 (cross-list from physics.space-ph) [pdf, other]

Title: MMS SITL Ground Loop: Automating the burst data selection process

Authors: Matthew R. Argall, Colin Small, Samantha Piatt, Liam Breen, Marek Petrik, Julie Barnum, Kim Kokkonen, Kristopher Larsen, Frederick D. Wilder, Mitsuo Oka, Roy B. Torbert, Robert E. Ergun, Tai Phan, Barbara L. Giles, James L. Burch

Comments: 21 pages, 5 figures, 3 tables, submitted to Frontiers: Space Science

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

Global-scale energy flow throughout Earth's magnetosphere is catalyzed by processes that occur at Earth's magnetopause (MP) in the electron diffusion region (EDR) of magnetic reconnection. Until the launch of the Magnetospheric Multiscale (MMS) mission, only rare, fortuitous circumstances permitted a glimpse of the electron dynamics that break magnetic field lines and energize plasma. MMS employs automated burst triggers onboard the spacecraft and a Scientist-in-the-Loop (SITL) on the ground to select intervals likely to contain diffusion regions. Only low-resolution survey data is available to the SITL, which is insufficient to resolve electron dynamics. A strategy for the SITL, then, is to select all MP crossings. This has resulted in over 35 potential MP EDR encounters but is labor- and resource-intensive; after manual reclassification, just 0.7% of MP crossings, or 0.0001% of the mission lifetime during MMS's first two years contained an EDR. We introduce a Long-Short Term Memory (LSTM) Recurrent Neural Network (RNN) to detect MP crossings and automate the SITL classification process. The LSTM has been implemented in the MMS data stream to provide automated predictions to the SITL. This model facilitates EDR studies and helps free-up mission operation costs by consolidating manual classification processes into automated routines.

[50]  arXiv:2004.07232 (cross-list from nucl-th) [pdf, other]

Title: How well do we know the neutron-matter equation of state at the densities inside neutron stars? A Bayesian approach with correlated uncertainties

Authors: C. Drischler, R. J. Furnstahl, J. A. Melendez, D. R. Phillips

Comments: 7 pages, 2 figures; supplemental material

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

We introduce a new framework for quantifying correlated uncertainties of the infinite-matter equation of state (EOS) derived from chiral effective field theory ($\chi$EFT). Bayesian machine learning, via Gaussian Processes with physics-based hyperparameters, allows us to efficiently quantify and propagate theoretical uncertainties of the EOS, such as $\chi$EFT truncation errors, to derived quantities. We apply this framework to state-of-the-art many-body perturbation theory calculations with consistent nucleon-nucleon and three-nucleon interactions up to fourth order in the $\chi$EFT expansion. This produces the first statistically meaningful uncertainty estimates for key quantities of neutron stars. We give results up to twice nuclear saturation density for the energy per particle, pressure, and speed of sound of neutron matter, as well as for the nuclear symmetry energy and its derivative. At nuclear saturation density the predicted symmetry energy and its slope are consistent with experimental constraints.

Replacements for Thu, 16 Apr 20

[51]  arXiv:1704.05871 (replaced) [pdf, other]

Title: Shape of the acoustic gravitational wave power spectrum from a first order phase transition

Authors: Mark Hindmarsh, Stephan J. Huber, Kari Rummukainen, David J. Weir

Comments: 16+1 pages, 9+1 figures; v2: added a few paragraphs about the importance of turbulence, published in PRD; v3: added erratum correcting two equations and the SNR plot, methods and conclusions unchanged

Journal-ref: Phys. Rev. D 96, 103520 (2017); Erratum: Phys. Rev. D 101, 089902 (2020)

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

[52]  arXiv:1710.07487 (replaced) [pdf, other]

Title: Inflaton fragmentation in E-models of cosmological $α$-attractors

Authors: Fuminori Hasegawa, Jeong-Pyong Hong

Comments: 8 pages, 6 figures

Journal-ref: Phys. Rev. D 97, 083514 (2018)

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

[53]  arXiv:1908.08472 (replaced) [pdf, ps, other]

Title: Measuring $H_0$ with pulsar timing arrays

Authors: Domènec Espriu, Luciano Gabbanelli, Marc Rodoreda

Comments: 25 pages, 11 figures, 2 tables

Journal-ref: Class. Quant. Grav. 37: 085013 (2020)

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

[54]  arXiv:1909.11095 (replaced) [pdf, other]

Title: Cross-correlating Planck with VST ATLAS LRGs: a new test for the ISW effect in the Southern Hemisphere

Authors: Behzad Ansarinejad (1), Ruari Mackenzie (2), Tom Shanks (1), Nigel Metcalfe (1) ((1) Durham University, (2) ETH Zurich)

Comments: 16 pages, 13 figures, accepted by MNRAS

Journal-ref: MNRAS. 493 (2020) 4830-4844

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

[55]  arXiv:1910.06306 (replaced) [pdf, other]

Title: STRIDES: a 3.9 per cent measurement of the Hubble constant from the strong lens system DES J0408-5354

Authors: A. J. Shajib, S. Birrer, T. Treu, A. Agnello, E. J. Buckley-Geer, J. H. H. Chan, L. Christensen, C. Lemon, H. Lin, M. Millon, J. Poh, C. E. Rusu, D. Sluse, C. Spiniello, G. C.-F. Chen, T. Collett, F. Courbin, C. D. Fassnacht, J. Frieman, A. Galan, D. Gilman, A. More, T. Anguita, M. W. Auger, V. Bonvin, R. McMahon, G. Meylan, K. C. Wong, T. M. C. Abbott, J. Annis, S. Avila, K. Bechtol, D. Brooks, D. Brout, D. L. Burke, A. Carnero Rosell, M. Carrasco Kind, J. Carretero, F. J. Castander, M. Costanzi, L. N. da Costa, J. De Vicente, S. Desai, J. P. Dietrich, P. Doel, A. Drlica-Wagner, A. E. Evrard, D. A. Finley, B. Flaugher, P. Fosalba, J. García-Bellido, D. W. Gerdes, D. Gruen, R. A. Gruendl, J. Gschwend, G. Gutierrez, D. L. Hollowood, K. Honscheid, D. Huterer, D. J. James, T. Jeltema, E. Krause, et al. (29 additional authors not shown)

Comments: 32 pages, 17 figures, 10 tables. Accepted by MNRAS

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

[56]  arXiv:1911.05714 (replaced) [pdf, other]

Title: Imaging Systematics and Clustering of DESI Main Targets

Authors: Ellie Kitanidis, Martin White, Yu Feng, David Schlegel, Julien Guy, Arjun Dey, Martin Landriau, David Brooks, Michael Levi, John Moustakas, Francisco Prada, Gregory Tarle, Benjamin Alan Weaver

Comments: 30 pages, 28 figures, 11 tables; v2: minor revisions to incorporate referee comments

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

[57]  arXiv:1911.09614 (replaced) [pdf, other]

Title: Baryon-driven growth of solitonic cores in fuzzy dark matter halos

Authors: Jan Veltmaat, Bodo Schwabe, Jens C. Niemeyer

Comments: 6 pages, 6 figures, matches published version

Journal-ref: Phys. Rev. D 101, 083518 (2020)

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

[58]  arXiv:1911.11778 (replaced) [pdf, other]

Title: SPECULATOR: Emulating stellar population synthesis for fast and accurate galaxy spectra and photometry

Authors: Justin Alsing, Hiranya Peiris, Joel Leja, ChangHoon Hahn, Rita Tojeiro, Daniel Mortlock, Boris Leistedt, Benjamin D. Johnson, Charlie Conroy

Comments: 15 pages, 9 figures, accepted by ApJS April 2020

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

[59]  arXiv:1912.05299 (replaced) [pdf, other]

Title: Colliding-wind binary systems: Diffusive shock acceleration and non-thermal emission

Authors: J. M. Pittard, G. S. Vila, G. E. Romero

Comments: 18 pages, 24 figures, accepted by MNRAS

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

[60]  arXiv:1912.08820 (replaced) [pdf, other]

Title: Survival of Primordial Planetary Atmospheres: Mass Loss from Temperate Terrestrial Planets

Authors: Alex R. Howe, Fred C. Adams, Michael R. Meyer

Comments: Accepted to ApJ. This draft includes revisions to the original mass loss estimates. (24 pages, 1 figure, 3 tables)

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

[61]  arXiv:2001.11505 (replaced) [pdf, other]

Title: A little theory of everything, with heavy neutral leptons

Authors: James M. Cline, Matteo Puel, Takashi Toma

Comments: 34 pages, 7 figures; v2: improved version with discussion of DM indirect detection, additional HNL decay channels, references added; v3: added constraints from rare LFV decays

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

[62]  arXiv:2003.07251 (replaced) [pdf, ps, other]

Title: First observations and magnitude measurement of Starlink's Darksat

Authors: J. Tregloan-Reed, A. Otarola, E. Ortiz, V. Molina, J. Anais, R. González, J. P. Colque, E. Unda-Sanzana

Comments: Letter accepted for publication to A&A. 5 Pages, 2 figures and 4 tables

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

[63]  arXiv:2003.10035 (replaced) [pdf, ps, other]

Title: Time Variability of Nonthermal X-ray Stripes in Tycho's Supernova Remnant with Chandra

Authors: Tomoyuki Okuno, Takaaki Tanaka, Hiroyuki Uchida, Felix A. Aharonian, Yasunobu Uchiyama, Takeshi Go Tsuru, Masamune Matsuda

Comments: 8 pages, 3 figures, 2 tables, accepted for publication in ApJ

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

[64]  arXiv:2004.00355 (replaced) [pdf, other]

Title: Evidence for a Coronal Shock Wave Origin for Relativistic Protons Producing Solar Gamma-Rays and Observed by Neutron Monitors at Earth

Authors: Athanasios Kouloumvakos, Alexis P. Rouillard, Gerald H. Share, Illya Plotnikov, Ronald Murphy, Athanasios Papaioannou, Yihong Wu

Comments: Accepted for publication in APJ, 18 pages, 12 figures

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

[65]  arXiv:2004.02506 (replaced) [pdf, other]

Title: An experimental study of the surface formation of methane in interstellar molecular clouds

Authors: D. Qasim, G. Fedoseev, K.-J. Chuang, J. He, S. Ioppolo, E.F. van Dishoeck, H. Linnartz

Journal-ref: Nature Astronomy April 2020

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

[66]  arXiv:2004.02969 (replaced) [pdf, other]

Title: Deciphering the Large-Scale Environment of Radio Galaxies in the Local Universe II. A Statistical Analysis of Environmental Properties

Authors: F. Massaro (UniTO, INAF-OATo, INFN-To, CIFS), A. Capetti (INAF-OATo), A. Paggi (UniTO, INAF-OATo, INFN-To), R. D. Baldi (UniTO, Univ. of Southampton), A. Tramacere (Univ. Geneve), I. Pillitteri (INAF-OAPa), R. Campana (INAF-OAS), A. Jimenez-Gallardo (UnitO, INAF-OATo), V. Missaglia (SAO)

Comments: 15 pages, 21 figures, 3 tables, ApJS in press (pre-proof version)

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

[67]  arXiv:2004.04074 (replaced) [pdf, other]

Title: Rastall gravity extension of the standard $Λ$CDM model: Theoretical features and observational constraints

Authors: Ozgur Akarsu, Nihan Katirci, Suresh Kumar, Rafael C. Nunes, Burcu Ozturk, Shivani Sharma

Comments: 17 pages, 10 figures, 2 tables; the results, discussions and conclusions are updated with some BAO data points

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

[68]  arXiv:2004.04202 (replaced) [pdf, other]

Title: The ELM Survey South. I. An Effective Search for Extremely Low Mass White Dwarfs

Authors: Alekzander Kosakowski, Mukremin Kilic, Warren R. Brown, Alexandros Gianninas

Comments: 25 pages, 15 figures, 8 tables

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

[69]  arXiv:2004.04833 (replaced) [pdf, other]

Title: 2D-FFTLog: Efficient computation of real space covariance matrices for galaxy clustering and weak lensing

Authors: Xiao Fang, Tim Eifler, Elisabeth Krause

Comments: 12 pages, 3 figures, 2 tables; 2DFFTLog code available at this https URL ; 3x2pt covariance code CosmoCov at this https URL

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

[70]  arXiv:2004.05590 (replaced) [pdf]

Title: Mid-Frequency Gravitational Wave Detection and Sources

Authors: Wei-Tou Ni

Comments: reference update and minor corrections

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

[71]  arXiv:2004.06270 (replaced) [pdf, other]

Title: Pykat: Python package for modelling precision optical interferometers

Authors: Daniel D. Brown, Philip Jones, Samuel Rowlinson, Andreas Freise, Sean Leavey, Anna C. Green, Daniel Toyra

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

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