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New submissions for Thu, 23 Apr 20

[1]  arXiv:2004.10204 [pdf, other]

Title: COLDz: A High Space Density of Massive Dusty Starburst Galaxies ~1 Billion Years after the Big Bang

Authors: Dominik A. Riechers (Cornell, MPIA), Jacqueline A. Hodge (Leiden), Riccardo Pavesi (Cornell), Emanuele Daddi (CEA), Roberto Decarli (INAF Bologna), Rob J. Ivison (ESO), Chelsea E. Sharon (Yale-NUS), Ian Smail (Durham), Fabian Walter (MPIA, NRAO), Manuel Aravena (Diego Portales), Peter L. Capak (IPAC/Caltech), Christopher L. Carilli (NRAO, Cambridge), Pierre Cox (IAP), Elisabete da Cunha (ANU), Helmut Dannerbauer (IAC), Mark Dickinson (NOIRLab), Roberto Neri (IRAM), Jeff Wagg (SKA)

Comments: 30 pages, 15 figures, 8 tables, to appear in ApJ (accepted April 21, 2020)

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

We report the detection of CO($J$=2$\to$1) emission from three massive dusty starburst galaxies at $z$$>$5 through molecular line scans in the NSF's Karl G. Jansky Very Large Array (VLA) CO Luminosity Density at High Redshift (COLDz) survey. Redshifts for two of the sources, HDF 850.1 ($z$=5.183) and AzTEC-3 ($z$=5.298), were previously known. We revise a previous redshift estimate for the third source GN10 ($z$=5.303), which we have independently confirmed through detections of CO $J$=1$\to$0, 5$\to$4, 6$\to$5, and [CII] 158 $\mu$m emission with the VLA and the NOrthern Extended Milllimeter Array (NOEMA). We find that two currently independently confirmed CO sources in COLDz are "optically dark", and that three of them are dust-obscured galaxies at $z$$>$5. Given our survey area of $\sim$60 arcmin$^2$, our results appear to imply a $\sim$6-55 times higher space density of such distant dusty systems within the first billion years after the Big Bang than previously thought. At least two of these $z$$>$5 galaxies show star-formation rate surface densities consistent with so-called "maximum" starbursts, but we find significant differences in CO excitation between them. This result may suggest that different fractions of the massive gas reservoirs are located in the dense, star-forming nuclear regions - consistent with the more extended sizes of the [CII] emission compared to the dust continuum and higher [CII]-to-far-infrared luminosity ratios in those galaxies with lower gas excitation. We thus find substantial variations in the conditions for star formation between $z$$>$5 dusty starbursts, which typically have dust temperatures $\sim$57%$\pm$25% warmer than starbursts at $z$=2-3 due to their enhanced star formation activity.

[2]  arXiv:2004.10205 [pdf, other]

Title: Merging Compact Binaries Near a Rotating Supermassive Black Hole: Eccentricity Excitation due to Apsidal Precession Resonance

Authors: Bin Liu, Dong Lai

Comments: 12 pages, 9 figures, 1 appendix. To be submitted

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

We study the dynamics of merging compact binaries near a rotating supermassive black hole (SMBH) in a hierarchical triple configuration. We include various general relativistic effects that couple the inner orbit, the outer orbit and the spin of the SMBH. During the orbital decay due to gravitational radiation, the inner binary can encounter an "apsidal precession resonance" and experience eccentricity excitation. This resonance occurs when the apsidal precession rate of the inner binary matches that of the outer binary, with the precessions driven by both Newtonian interactions and various post-Newtonian effects. The eccentricity excitation requires the outer orbit to have a finite eccentricity, and is most effective for triples with small mutual inclinations, in contrast to the well-studied Lidov-Kozai effect. The resonance and the associated eccentricity growth may occur while the binary emits gravitational waves in the low-frequency band, and may be detectable by future space-based gravitational wave detectors.

[3]  arXiv:2004.10206 [pdf, other]

Title: It's Dust: Solving the Mysteries of the Intrinsic Scatter and Host-Galaxy Dependence of Standardized Type Ia Supernova Brightnesses

Authors: Dillon Brout, Daniel Scolnic

Comments: 15 pages, 11 figures

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

The use of Type Ia Supernovae (SNe Ia) as cosmological tools has motivated significant effort to: understand what drives the intrinsic scatter of SN Ia distance modulus residuals after standardization, characterize the distribution of SN Ia colors, and explain why properties of the host galaxies of the SNe correlate with SN Ia distance modulus residuals. We use a compiled sample of $\sim1450$ spectroscopically confirmed, photometric light-curves of SN Ia and propose a solution to these three problems simultaneously that also explains an empirical 11$\sigma$ detection of the dependence of Hubble residual scatter on SN Ia color. We introduce a physical model of color where intrinsic SN Ia colors with a relatively weak correlation with luminosity are combined with extrinsic dust-like colors ($E(B-V)$) with a wide range of extinction parameter values ($R_V$). This model captures the observed trends of Hubble residual scatter and indicates that the dominant component of SN Ia intrinsic scatter is from variation in $R_V$. We also find that the recovered $E(B-V)$ and $R_V$ distributions differ based on global host-galaxy stellar mass and this explains the observed correlation ($\gamma$) between mass and Hubble residuals seen in past analyses as well as an observed 4.5$\sigma$ dependence of $\gamma$ on SN Ia color. This finding removes any need to prescribe different intrinsic luminosities to different progenitor systems. Finally we measure biases in the equation-of-state of dark energy ($w$) up to $|\Delta w|=0.04$ by replacing previous models of SN color with our dust-based model; this bias is larger than any systematic uncertainty in previous SN Ia cosmological analyses.

[4]  arXiv:2004.10207 [pdf, other]

Title: Hubble constant tension between CMB lensing and BAO measurements

Authors: W.L. Kimmy Wu, Pavel Motloch, Wayne Hu, Marco Raveri

Comments: 9 pages, 9 figures. Comments are welcome

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

We apply a tension metric $Q_\textrm{UDM}$, the update difference in mean parameters, to understand the source of the difference in the measured Hubble constant $H_0$ inferred with cosmic microwave background lensing measurements from the Planck satellite ($H_0=67.9^{+1.1}_{-1.3}\, \mathrm{km/s/Mpc}$) and from the South Pole Telescope ($H_0=72.0^{+2.1}_{-2.5}\, \mathrm{km/s/Mpc}$) when both are combined with baryon acoustic oscillation (BAO) measurements with priors on the baryon density (BBN). $Q_\textrm{UDM}$ isolates the relevant parameter directions for tension or concordance where the two data sets are both informative, and aids in the identification of subsets of data that source the observed tension. With $Q_\textrm{UDM}$, we uncover that the difference in $H_0$ is driven by the tension between Planck lensing and BAO+BBN, at probability-to-exceed of 6.6%. Most of this mild tension comes from the galaxy BAO measurements parallel to the line of sight. The redshift dependence of the parallel BAOs pulls both the matter density $\Omega_m$ and $H_0$ high in $\Lambda$CDM, but these parameter anomalies are usually hidden when the BAO measurements are combined with other cosmological data sets with much stronger $\Omega_m$ constraints.

[5]  arXiv:2004.10209 [pdf, other]

Title: A Model-Insensitive Baryon Acoustic Oscillation Feature in the 21 cm Signal from Reionization

Authors: Christopher Cain, Anson D'Aloisio, Vid Iršič, Matthew McQuinn, Hy Trac

Comments: 26 pages, 12 figures

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

We examine the impact of the baryon-dark matter relative velocity on intergalactic small-scale structure and the 21 cm signal during the epoch of reionization (EoR). Streaming velocities reduced the clumping of the intergalactic medium (IGM) on mass scales of $\sim 10^4 - 10^8$ M$_{\odot}$. This effect produced a distinct baryon acoustic oscillation (BAO) feature in the EoR 21 cm power spectrum at wave numbers $k\sim 0.1$ h/Mpc, near which forthcoming surveys will be most sensitive. In contrast to the highly uncertain impact of streaming velocities on star formation, the effect on clumping can be calculated more precisely because it is set mainly by cosmology and straightforward gas dynamics. We quantify the latter using fully coupled radiation-hydrodynamics simulations that capture the Jeans scale of the pre-EoR gas. The clumping factor of ionized gas is reduced by 5-10\% in regions that had typical streaming velocities of 30 km/s at recombination. The suppression peaks $\approx 5$ Myr after a region is reionized, but washes out within 200 Myr due to pressure smoothing of the gas. Using these results, we model the corresponding impact on the EoR 21 cm power spectrum and find that the BAO feature is most likely to appear early in reionization ($\approx$ 10 \% ionization).During this phase, the signal may appear at the 1 \% (5 \%) level at $k \sim 0.1 (0.06)$ h/\Mpc with an amplitude that varies by less than a factor of 10 across a range of reionization histories. We also provide a simple model for the signal originating from streaming velocity's impact on ionizing sources, which can vary by 4 orders of magnitude depending on highly uncertain source properties. We find that the clumping-driven signal is likely to dominate the source-driven one unless population III star formation in halos of masses $10^6 - 10^8$ M$_{\odot}$ was efficient enough to drive the first 10\% of reionization.

[6]  arXiv:2004.10210 [pdf, other]

Title: Intrinsic properties of the engine and jet that powered the short gamma-ray burst associated with GW170817

Authors: Davide Lazzati (Oregon State), Riccardo Ciolfi (INAF - Padova), Rosalba Perna (Stony Brook)

Comments: Submitted for consideration to AAS journals

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

GRB 170817A was a subluminous short gamma-ray burst detected about 1.74 s after the gravitational wave signal GW170817 from a binary neutron star (BNS) merger. It is now understood as an off-axis event powered by the cocoon of a relativistic jet pointing 15 to 30 degrees away from the direction of observation. The cocoon was energized by the interaction of the incipient jet with the non-relativistic baryon wind from the merger remnant, resulting in a structured outflow with a narrow core and broad wings. In this paper, we couple the observational constraints on the structured outflow with a model for the jet-wind interaction to constrain the intrinsic properties with which the jet was launched by the central engine, including its time delay from the merger event. Using wind prescriptions inspired by magnetized BNS merger simulations, we find that the jet was launched within about 0.4 s from the merger, implying that the 1.74 s observed delay was dominated by the fireball propagation up to the photospheric radius. We also constrain, for the first time for any gamma-ray burst, the jet opening angle at injection and set a lower limit to its asymptotic Lorentz factor. These findings suggest an initially Poynting-flux dominated jet, launched via electromagnetic processes. If the jet was powered by an accreting black hole, they also provide a significant constraint on the survival time of the metastable neutron star remnant.

[7]  arXiv:2004.10213 [pdf, other]

Title: Measuring Star Formation Histories, Distances, and Metallicities with Pixel Color-Magnitude Diagrams II: Applications to Nearby Elliptical Galaxies

Authors: B. A. Cook (1), Charlie Conroy (1), Pieter van Dokkum (2) ((1) Center for Astrophysics | Harvard & Smithsonian, (2) Astronomy Department, Yale University)

Comments: 18 pages, accepted for publication in ApJ

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

We present spatially-resolved measurements of star formation histories (SFHs), metallicities, and distances in three nearby elliptical galaxies and the bulge of M31 derived using the pixel color-magnitude diagram (pCMD) technique. We compute pCMDs from archival $\textit{HST}$ photometry of M87, M49, NGC 3377 and M31, and fit the data using the new code $\texttt{PCMDPy}$. We measure distances to each system that are accurate to $\sim 10\%$. The recovered non-parametric SFHs place reasonable ($\pm 1$ dex) constraints on the recent (< 2 Gyr) star formation in M31 and NGC 3377, both of which show evidence of inside-out growth. The SFHs in M87 and M49 are constrained only at the oldest ages. The pCMD technique is a promising new avenue for studying the evolutionary history of the nearby universe, and is highly complementary to existing stellar population modeling techniques.

[8]  arXiv:2004.10214 [pdf, other]

Title: Size distribution of superbubbles

Authors: Biman B Nath, Pushpita Das, M. S. Oey

Comments: 12 pages, 16 figures, Published in MNRAS

Journal-ref: 2020, MNRAS, 493, 1034-1043

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

We consider the size distribution of superbubbles in a star forming galaxy. Previous studies have tried to explain the distribution by using adiabatic self-similar evolution of wind driven bubbles, assuming that bubbles stall when pressure equilibrium is reached. We show, with the help of hydrodynamical numerical simulations, that this assumption is not valid. We also include radiative cooling of shells. In order to take into account non-thermal pressure in the ambient medium, we assume an equivalent higher temperature than implied by thermal pressure alone. Assuming that bubbles stall when the outer shock speed becomes comparable to the ambient sound speed (which includes non-thermal components), we recover the size distribution with a slope of $\sim -2.7$ for typical values of ISM pressure in Milky Way, which is consistent with observations. Our simulations also allow us to follow the evolution of size distribution in the case of different values of non-thermal pressure, and we show that the size distribution steepens with lower pressure, to slopes intermediate between only-growing and only-stalled cases.

[9]  arXiv:2004.10223 [pdf, other]

Title: Towards Universal Cosmological Emulators with Generative Adversarial Networks

Authors: Andrius Tamosiunas, Hans A. Winther, Kazuya Koyama, David J. Bacon, Robert C. Nichol, Ben Mawdsley

Comments: 30 pages, 21 figures, 1 table

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

Generative adversarial networks (GANs) have been recently applied as a novel emulation technique for large scale structure simulations. Recent results show that GANs can be used as a fast, efficient and computationally cheap emulator for producing novel weak lensing convergence maps as well as cosmic web data in 2-D and 3-D. However, like any algorithm, the GAN approach comes with a set of limitations, such as an unstable training procedure and the inherent randomness of the produced outputs. In this work we employ a number of techniques commonly used in the machine learning literature to address the mentioned limitations. In particular, we train a GAN to produce both weak lensing convergence maps and dark matter overdensity field data for multiple redshifts, cosmological parameters and modified gravity models. In addition, we train a GAN using the newest Illustris data to emulate dark matter, gas and internal energy distribution data simultaneously. Finally, we apply the technique of latent space interpolation to control which outputs the algorithm produces. Our results indicate a 1-20% difference between the power spectra of the GAN-produced and the training data samples depending on the dataset used and whether Gaussian smoothing was applied. Finally, recent research on generative models suggests that such algorithms can be treated as mappings from a lower-dimensional input (latent) space to a higher dimensional (data) manifold. We explore such a theoretical description as a tool for better understanding the latent space interpolation procedure.

[10]  arXiv:2004.10230 [pdf, other]

Title: The Star Formation in Radio Survey: 3 - 33 GHz Imaging of Nearby Galaxy Nuclei and Extranuclear Star-forming Regions

Authors: S.T. Linden, E.J. Murphy, D. Dong, E. Momjian, R. C. Kennicutt Jr., D.S. Meier, E. Schinnerer, J.L. Turner

Comments: 57 pages, 23 figures, 7 tables, accepted for publication in ApJS

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

We present 3, 15, and 33 GHz imaging towards galaxy nuclei and extranuclear star-forming regions using the Karl G. Jansky Very Large Array as part of the Star Formation in Radio Survey. With $3-33$ GHz radio spectra, we measured the spectral indices and corresponding thermal (free-free) emission fractions for a sample of 335 discrete regions having significant detections in at least two radio bands. After removing 14 likely background galaxies, we find that the median thermal fraction at 33 GHz is $92 \pm 0.8\%$ with a median absolute deviation of $11\%$, when a two-component power-law model is adopted to fit the radio spectrum. Limiting the sample to 238 sources that are confidently identified as star-forming regions, and not affected by potential AGN contamination (i.e., having galactocentric radii $r_{\rm G} \geq 250$ pc), results in a median thermal fraction of $93 \pm 0.8 \%$ with a median absolute deviation of $10\%$. We further measure the thermal fraction at 33 GHz for 163 regions identified at 7" resolution to be $94 \pm 0.8 \%$ with a median absolute deviation of $8\%$. Together, these results confirm that free-free emission dominates the radio spectra of star-forming regions on scales up to $\sim$500 pc in normal star-forming galaxies. We additionally find a factor of $\sim$1.6 increase in the scatter of the measured spectral index and thermal fraction distributions as a function of decreasing galactocentric radius. This trend is likely reflective of the continuous star-formation activity occurring in the galaxy centers, resulting a larger contribution of diffuse nonthermal emission relative to star-forming regions in the disk.

[11]  arXiv:2004.10238 [pdf, other]

Title: The Composition, Excitation, and Physical State of Atomic Gas in the Debris Disk Surrounding 51 Oph

Authors: Edward B. Jenkins (Princeton University Observatory), Cecile Gry (Laboratoire d'Astrophysique de Marseille)

Comments: 66 pages, 11 figures. To be published in the Astrophysical Journal

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

We measured 304 absorption features in the ultraviolet and visible spectra of the star 51 Oph, which is known to have a debris disk with a high inclination. We analyzed the relative populations of atoms in excited fine-structure and metastable levels that are maintained by optical pumping and collisional excitation by electrons, and we found that most of the gas is situated at about 6AU from the star, has an electron volume density $10^5 < n(e) < 3\times 10^6{\rm cm}^{-3}$, and a temperature T=8000K. Our interpretations reveal that the gas is partly ionized, has a column density of neutral hydrogen equal to $10^{21}\,{\rm cm}^{-2}$, and has a composition similar to that of a mildly depleted interstellar medium or that of Jupiter-family comets. Compared to results for disks around some other stars, such as $\beta$ Pic and 49 Cet, we find surprisingly little neutral carbon. No molecular features were detected, which indicates that our line of sight misses the molecule-rich central plane of the disk. The tilt of the disk is also validated by our being able to detect resonant scattering of the starlight by oxygen atoms.

[12]  arXiv:2004.10244 [pdf, ps, other]

Title: Dust Reverberation of 3C273: torus structure and lag -- luminosity relation

Authors: Catalina Sobrino Figaredo, Martin Haas, Michael Ramolla, Rolf Chini, Julia Blex, Klaus-Werner Hodapp, Miguel Murphy, Wolfram Kollatschny, Doron Chelouche, Shai Kaspi

Comments: 24 pages, 19 Figures, accepted for publication in the Astronomical Journal

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

We monitored the z=0.158 quasar 3C273 between 2015 and 2019 in the optical (BVrz) and near-infrared (JHK) with the aim to perform dust reverberation mapping. Accounting for host galaxy and accretion disk contributions, we obtained pure dust light curves in JHK. Cross correlations between the V-band and the dust light curves yield an average rest-frame delay for the hot dust of tau_cent ~ 410 days. This is a factor 2 shorter than expected from the the dust ring radius R_x ~ 900 light days reported from interferometric studies. The dust covering factor (CF) is about 8%, much smaller than predicted from the half covering angle of 45 degree found for active galactic nuclei (AGN). We analyse the asymmetric shape of the correlation functions and explore whether an inclined bi-conical bowl-shaped dust torus geometry could bring these findings (tau_cent, R_x and CF) into a consistent picture. The hot varying dust emission originates from the edge of the bowl rim with a small covering angle 40 < theta < 45 degree, and we see only the near side of the bi-conus. Such a dust gloriole with R_x = 900 +/- 200 ld and an inclination i = 12 degree matches the data remarkably well. Comparing the results of 3C273 with literature for less luminous AGN, we find a lag-luminosity relation tau propto L^alpha with alpha between 0.33 and 0.40, flatter than the widely adopted relation with alpha = 0.5. We address several explanations for the new lag - luminosity relation.

[13]  arXiv:2004.10260 [pdf, other]

Title: Late time cosmological evolution in DHOST models

Authors: Hamza Boumaza, David Langlois, Karim Noui

Comments: 17 pages, 8 figures

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

We study the late cosmological evolution, from the nonrelativistic matter dominated era to the dark energy era, in modified gravity models described by Degenerate Higher-Order Scalar-Tensor (DHOST) theories. They represent the most general scalar-tensor theories propagating a single scalar degree of freedom and include Horndeski and Beyond Horndeski theories. We provide the homogeneous evolution equations for any quadratic DHOST theory, without restricting ourselves to theories where the speed of gravitational waves coincides with that of light since the present constraints apply to wavelengths much smaller than cosmological scales. To illustrate the potential richness of the cosmological background evolution in these theories, we consider a simple family of shift-symmetric models, characterized by three parameters and compute the evolution of dark energy and of its equation of state. We also identify the regions in parameter space where the models are perturbatively stable.

[14]  arXiv:2004.10266 [pdf, other]

Title: Ionic emissions in comet C/2016 R2 (Pan-STARRS)

Authors: Kumar Venkataramani, Shashikiran Ganesh, Kiran S.Baliyan

Comments: Accepted for Publication in MNRAS

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

We carried out observations of a peculiar comet, C/2016 R2 (Pan-STARRS), using a low resolution spectrograph mounted on the 1.2m telescope at Mount Abu Infrared Observatory, India. The comet was observed on two dates in January 2018, when it was at a heliocentric distance of 2.8 AU. Study based on our observations revealed that the optical spectrum of this comet is quite unusual as compared to general cometary spectra. Most of the major cometary emissions like C$_{2}$, C$_{3}$ and CN were absent in comet C/2016 R2. However, the comet spectrum showed very strong emission bands from ionic species like CO$^{+}$ and N$_{2}^{+}$. A mean N$_{2}$/CO ratio of 0.09 $\pm$ 0.02 was derived from the spectra and an extremely low depletion factor of 1.6 $\pm$ 0.4 has been estimated for this ratio as compared to the solar nebula. We have also detected minor emission features beyond 5400 Angstroms, albeit marginally. The column densities of CO$^{+}$ and N$_{2}^{+}$ were calculated from their emission bands. The optical spectrum suggests that the cometary ice is dominated by CO. The low depletion factor of N$_{2}$/CO ratio in this comet, as compared to the solar nebula and the unusual spectrum of the comet are consequences of distinctive processing at the location of its formation in the early solar nebula.

[15]  arXiv:2004.10294 [pdf, other]

Title: Characterizing aperture masking interferometry in the near-infrared as an effective technique for astronomical imaging

Authors: Kyle Morgenstein

Comments: 21 pages, abstract accepted to AAS Winter Meeting

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

Radio interferometry is the current method of choice for deep space astronomy, but in the past few decades optical techniques have become increasingly common. This research seeks to characterize the performance of aperture masking interferometry in the near-infrared at small scales. A mask containing six pairs of apertures at varying diameters and separations was constructed for use with a 24-inch telescope at the MIT Wallace Astrophysical Observatory. Test images of Spica and Jupiter were captured for 28 different telescope configurations, varying aperture separation, aperture diameter, collection wavelength, and exposure time. Lucky imaging was used to account for atmospheric perturbations. Each image was reduced via bias and dark frames to account for sensor noise, and then the full width at half maximum for each image was computed and used as a proxy for maximum angular resolution. The data imply that at small scales aperture size primarily controls the observed maximum angular resolution, but further data are required to substantiate the claim.

[16]  arXiv:2004.10296 [pdf, ps, other]

Title: Decrease in the Brightness of the Cosmic X-ray and Soft Gamma-ray Background toward Clusters of Galaxies

Authors: S. A. Grebenev (1), R. A. Sunyaev (1,2) ((1) Space Research Institute, Russian Academy of Sciences, (2) Max-Planck-Institut fuer Astrophysik)

Comments: 25 pages, 15 figures, 4 tables

Journal-ref: Astronomy Letters, 45 (2019), 791-820

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

We show that Compton scattering by electrons of the hot intergalactic gas in galaxy clusters should lead to peculiar distortions of the cosmic background X-ray and soft gamma-ray radiation - an increase in its brightness at E<60-100 keV and a drop at higher energies. The distortions allow the most important cluster parameters to be measured. The spectral shape of the distortions and its dependence on the gas temperature, optical depth, and surface density distribution law have been studied using Monte Carlo computations and confirmed by analytical estimations. In the cluster frame the maximum of the background decrease due to the recoil effect occurs at ~500-600 keV. The photoionization of H- and He-like iron and nickel ions leads to additional distortions in the background spectrum - a strong absorption line with the threshold at ~9 keV (and also to an absorption jump at ~2 keV for cold clusters). The absorption of intrinsic thermal radiation from the cluster gas by these ions also leads to such lines. In nearby (z<1) clusters the line at ~2 keV is noticeably enhanced by absorption in the colder (~10^6 K) plasma of their peripheral (~3 Mpc) regions; moreover, the absorption line at ~1.3 keV splits off from it. The redshift of distant clusters shifts the absorption lines in the background spectrum (at ~2, ~9, and ~500 keV) to lower energies. Thus, in contrast to the microwave background scattering effect, this effect depends on the cluster redshift z, but in a very peculiar way. When observing clusters at z>1, the effect allows one to determine how the X-ray background evolved and how it was "gathered" with z. To detect the effect, the accuracy of measurements should reach ~0.1%. We consider the most promising clusters for observing the effect and discuss the techniques whereby the influence of the thermal gas radiation hindering the detection of background distortions should be minimal.

[17]  arXiv:2004.10372 [pdf, other]

Title: X-ray absorption and 9.7 um silicate feature as a probe of AGN torus structure

Authors: Jun Xu (USTC), Mouyuan Sun (XMU), Yongquan Xue (USTC), Junyao Li (USTC), Zhicheng He (USTC)

Comments: 17 pages, 12 figures, Accepted to Research in Astronomy and Astrophysics

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

The dusty torus plays a vital role in unifying active galactic nuclei (AGNs). However, the physical structure of the torus remains largely unclear. Here we present a systematical investigation of the torus mid-infrared (MIR) spectroscopic feature, i.e., the 9.7 um silicate line, of $175$ AGNs selected from the Swift/BAT Spectroscopic Survey (BASS). Our sample is constructed to ensure that each of the $175$ AGNs has Spizter/IRS MIR, optical, and X-ray spectroscopic coverage. Therefore, we can simultaneously measure the silicate strength, optical emission lines, and X-ray properties (e.g., the column density and the intrinsic X-ray luminosity). We show that, consistent with previous works, the silicate strength is weakly correlated with the hydrogen column density ($N_\mathrm{H}^\mathrm{X}$), albeit with large scatters. For X-ray unobscured AGNs, the silicate-strength-derived $V$-band extinction and the broad-H$\alpha$-inferred one are both small; however, for X-ray obscured AGNs, the former is much larger than the latter. In addition, we find that the optical type 1 AGNs with strong X-ray absorption on average show significant silicate absorption, indicating that their X-ray absorption might not be caused by dust-free gas in the broad-line region. Our results suggest that the distribution and structure of the obscuring dusty torus are likely to be very complex. We test our results against the smooth and clumpy torus models and find evidence in favor of the clumpy torus model.

[18]  arXiv:2004.10406 [pdf, other]

Title: SN2020bvc: a Broad-lined Type Ic Supernova with a Double-peaked Optical Light Curve and a Luminous X-ray and Radio Counterpart

Authors: A. Y. Q. Ho (1), S. R. Kulkarni (1), D. A. Perley (2), S. B. Cenko (3,4), A. Corsi (5), S. Schulze (6), R. Lunnan (7), J. Sollerman (7), A. Gal-Yam (6), S. Anand (1), C. Barbarino (7), E. Bellm (8), R. Bruch (6), E. Burns (3,9), K. De (1), R. Dekany (10), A. Delacroix (10), D. Duev (1), C. Fremling (1), D. Goldstein (1), Z. Golkhou (8,11), M. J. Graham (1), D. Hale (10), M. M. Kasliwal (1), T. Kupfer (12), R. Laher (13), J. Martikainen (14,15), F. J. Masci (13), J. D. Neill (1), B. Rusholme (13), D. L. Shupe (13), M. T. Soumagnac (16,6), N. L. Strotjohann (6), K. Taggart (2), L. Tartaglia (7), L. Yan (10), J. Zolkower (10) ((1) Caltech, (2) LJMU, (3) NASA Goddard, (4) UMD, (5) TTU, (6) Weizmann, (7) OKC, (8) DIRAC Institute, (9) Louisiana State, (10) COO, (11) eScience Institute, (12) UCSB, (13) IPAC, (14) U. Helsinki, (15) NOT, (16) LBNL)

Comments: Subm to ApJ. 36 pages, 16 figures. Comments welcome

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

We present optical, radio, and X-ray observations of SN2020bvc (=ASASSN20bs; ZTF20aalxlis), a nearby ($z=0.0252$; $d$=114 Mpc) broad-lined (BL) Type Ic supernova (SN). Our observations show that SN2020bvc shares several properties in common with the Ic-BL SN2006aj, which was associated with the low-luminosity gamma-ray burst (LLGRB) 060218. First, the 10 GHz radio light curve is on the faint end of LLGRB-SNe ($L_\mathrm{radio} \approx 10^{37}$erg/s): we model our VLA observations (spanning 13-43 d) as synchrotron emission from a mildly relativistic ($v \gtrsim 0.3c$) forward shock. Second, with Swift and Chandra we detect X-ray emission ($L_X \approx 10^{41}$erg/s) that is not naturally explained as inverse Compton emission or as part of the same synchrotron spectrum as the radio emission. Third, high-cadence ($6\times$/night) data from the Zwicky Transient Facility (ZTF) shows a double-peaked optical light curve, the first peak from shock-cooling emission from extended low-mass material (mass $M<10^{-2} M_\odot$ at radius $R>10^{12}$cm) and the second peak from the radioactive decay of Ni-56. SN2020bvc is the first confirmed double-peaked Ic-BL SN discovered without a GRB trigger, and shows X-ray and radio emission similar to LLGRB-SNe: this is consistent with models in which the same mechanism produces both the LLGRB and the shock-cooling emission. For four of the five other nearby ($z\lesssim0.05$) Ic-BL SNe with ZTF high-cadence data, we rule out a first peak like that seen in SN2006aj and SN2020bvc, i.e. that lasts $\approx 1$d and reaches a peak luminosity $M \approx -18$. X-ray and radio follow-up observations of future such events will establish whether double-peaked optical light curves are indeed predictive of LLGRB-like X-ray and radio emission.

[19]  arXiv:2004.10407 [pdf, ps, other]

Title: LAMOST J202629.80+423652.0 is not a symbiotic star

Authors: V. Andreoli (ANS Collaboration), U. Munari (INAF Padova)

Journal-ref: Published in Contrib. Astron. Obs. Skalnate Pleso 50, 672-680 (2020)

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

LAMOST J202629.80+423652.0 has been recently classified as a new symbiotic star containing a long-period Mira, surrounded by dust (D-type) and displaying in the optical spectra high ionization emission lines, including the Raman-scattered OVI at 6825 Ang. We have observed LAMOST J202629.80+423652.0 photometrically in the BVRI bands and spectroscopically over the 3500-8000 Ang range. We have found it to be a normal G8IV sub-giant star, deprived of any emission line in its spectrum, and reddened by E(B-V)=0.35 mag. Combining our photometry with data from all-sky patrol surveys, we find LAMOST J202629.80+423652.0 to be non variable, so not pulsating as a Mira. We have compiled from existing sources its spectral energy distribution, extending well into the mid-Infrared, and found it completely dominated by the G8IV photospheric stellar emission, without any sign of circumstellar dust. We therefore conclude that LAMOST J202629.80+423652.0 is not a symbiotic star, nor it is pulsating or been enshrouded in dust.

[20]  arXiv:2004.10429 [pdf, other]

Title: Black Hole Shadow Observations with Space-Ground Interferometers

Authors: E. V. Mikheeva, S. V. Repin, V. N. Lukash (P.N. Lebedev Physical Institute of Russian Academy of Sciences, Moscow, Russia)

Comments: 15 pages, 5 figures

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

We consider the black hole (BH) shadow images which can be restored by data processing and image recovery procedures in future space Very Large Baseline Interferometry (VLBI) missions. For Kerr BHs with masses and coordinates of SgrA*, M87* and M31*, illuminated by light source behind them, we consider three kinds of observation: the ground-based interferometer (similar to the Event Horizon Telescope), space-ground interferometer with a satellite in geocentric orbit and space-ground interferometer with a satellite located in Lagrange point $L_2$. The significant difference between the images produced by the ground-based telescope alone and the one of the space VLBI with an added low-orbit satellite is caused by both the increased baseline and the improved of (u,v) coverage. The near-Earth configuration of the radio interferometer for the observation of BH shadows is the most preferable for the BH shadow observations among considered cases. With further increasing the orbit radius up to the Lagrange point $L_2$ the density of the (u,v) filling decreases and the results appear less reliable. Model images for all the cases are presented.

[21]  arXiv:2004.10452 [pdf, ps, other]

Title: NuSTAR observation of the Supergiant Fast X-ray Transient IGR J11215-5952 during its 2017 outburst

Authors: L. Sidoli (1), K. Postnov (2,3), A. Tiengo (4,5,1), P. Esposito (4,1), V. Sguera (6), A. Paizis (1), G.A. Rodrıguez Castillo (7) ((1)-INAF, IASF-Milano, Milano, Italy, (2)-Sternberg Astronomical Institute, M.V. Lomonosov Moscow State University, Moscow, Russia, (3)-Kazan Federal University, Russia, (4)-Scuola Universitaria Superiore IUSS Pavia, Italy, (5)-INFN, Sezione di Pavia, Italy, (6)-INAF, OAS Bologna, Italy, (7)-INAF, OAR, Monteporzio Catone (Roma), Italy)

Comments: Accepted for publication in Astronomy & Astrophysics (Received 3 April 2020 / Accepted 17 April 2020). 14 pages, 5 Tables, 9 Figures

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

We report on the results of a NuSTAR observation of the Supergiant Fast X-ray Transient pulsar IGRJ11215-5952 during the peak of its outburst in June 2017. IGRJ11215-5952 is the only SFXT undergoing strictly periodic outbursts, every 165 days. NuSTAR caught several X-ray flares, spanning a dynamic range of 100, and detected X-ray pulsations at 187.0 s, consistent with previous measurements. The spectrum from the whole observation is well described by an absorbed power-law (with a photon index of 1.4) modified, above 7 keV, by a cutoff with an e-folding energy of 24 keV. A weak emission line is present at 6.4 keV, consistent with Kalpha emission from cold iron in the supergiant wind. The time-averaged flux is 1.5E-10 erg/cm2/s (3-78 keV, corrected for the absorption), translating into an average luminosity of about 9E35 erg/s (1-100 keV, assuming a distance of 6.5 kpc). The NuSTAR observation allowed us to perform the most sensitive search for cyclotron resonant scattering features in the hard X-ray spectrum, resulting in no significant detection in any of the different spectral extractions adopted (time-averaged, temporally-selected, spin-phase-resolved and intensity-selected spectra). The pulse profile showed an evolution with both the energy (3-12 keV energy range compared with 12-78 keV band) and the X-ray flux: a double peaked profile was evident at higher fluxes (and in both energy bands), while a single peaked, sinusoidal profile was present at the lowest intensity state achieved within the NuSTAR observations (in both energy bands). The intensity-selected analysis allowed us to observe an anti-correlation of the pulsed fraction with the X-ray luminosity. The pulse profile evolution can be explained by X-ray photon scattering in the accreting matter above magnetic poles of a neutron star at the quasi-spherical settling accretion stage.

[22]  arXiv:2004.10500 [pdf, ps, other]

Title: Unveiling the physical conditions in NGC 6910

Authors: Harmeen Kaur, Saurabh Sharma, Lokesh K. Dewangan, Devendra K. Ojha, Alok Durgapal, Neelam Panwar

Comments: Accepted for publication in ApJ, 23 pages, 12 figures, 5 Tables

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

Deep and wide-field optical photometric observations along with multiwavelength archival datasets have been employed to study the physical properties of the cluster NGC 6910. The study also examines the impact of massive stars to their environment. The age, distance and reddening of the cluster are estimated to be $\sim$4.5 Myr, $1.72\pm0.08$ kpc, and $ E(B-V)_{min}= 0.95$ mag, respectively. The mass function slope ($\Gamma = -0.74\pm0.15$ in the cluster region is found to be flatter than the Salpeter value (-1.35), indicating the presence of excess number of massive stars. The cluster also shows mass segregation towards the central region due to their formation processes. The distribution of warm dust emission is investigated towards the central region of the cluster, showing the signature of the impact of massive stars within the cluster region. Radio continuum clumps powered by massive B-type stars (age range $\sim$ 0.07-0.12 Myr) are traced, which are located away from the center of the stellar cluster NGC 6910 (age $\sim$ 4.5 Myr). Based on the values of different pressure components exerted by massive stars, the photoionized gas associated with the cluster is found to be the dominant feedback mechanism in the cluster. Overall, the massive stars in the cluster might have triggered the birth of young massive B-type stars in the cluster. This argument is supported with evidence of the observed age gradient between the cluster and the powering sources of the radio clumps.

[23]  arXiv:2004.10504 [pdf, other]

Title: Thermal convection in the crust of the dwarf planet (1) Ceres

Authors: M.Formisano, C.Federico, J.Castillo-Rogez, M.C. De Sanctis, G.Magni

Journal-ref: Monthly Notices of the Royal Astronomical Society Main Journal, 2020

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

Ceres is the largest body in the Main Belt, and it is characterized by a large abundance of water ice in its interior. This feature is suggested by its relatively low bulk density (2162 kg m$^{-3}$), while its partial differentiation into a rocky core and icy crust is suggested by several geological and geochemical features: minerals and salts produced by aqueous alteration, icy patches on the surface, lobate morphology interpreted as surface flows. In this work we explore how the composition can influence the characteristics of thermal convection in the crust of Ceres. Our results suggest that the onset of thermal convection is difficult and when it occurs it is short lived and this could imply that Ceres preserved deep liquid until present, as recent suggested by the work of Castillo-Rogez et al.. Moreover, cryovolcanism could be driven by diapirism (chemical convection) rather than thermal convection.

[24]  arXiv:2004.10508 [pdf, ps, other]

Title: First Detection of Two Superoutbursts during Rebrightening Phase of a WZ Sge-type Dwarf Nova: TCP J21040470+4631129

Authors: Yusuke Tampo, Kojiguchi Naoto, Keisuke Isogai, Taichi Kato, Mariko Kimura, Yasuyuki Wakamatsu, Daisaku Nogami, Tonny Vanmunster, Tamás Tordai, Hidehiko Akazawa, Felipe Mugas, Taku Nishiumi, Víctor J. S. Béjar, Kiyoe Kawauchi, Nicolas Crouzet, Noriharu Watanabe, Núria Casasayas-Barris, Yuka Terada, Akihiko Fukui, Norio Narita, Enric Palle, Motohide Tamura, Nobuhiko Kusakabe, Roi Alonso, Hiroshi Itoh, Kirill Sokolovsky, Brandon McIntyre, Jesse Leahy-McGregor, Stephen M. Brincat, Pavol A. Dubovsky, Tomáš Medulka, Igor Kudzej, Elena P. Pavlenko, Kirill A. Antonyuk, Nikolaj V. Pit, Oksana I. Antonyuk, Julia V. Babina, Aleksei V. Baklanov, Aleksander S. Sklyanov, Alexandra M. Zubareva, Aleksandr A. Belinski, Alexandr V. Dodin, Marina A. Burlak, Natalia P. Ikonnikova, et al. (10 additional authors not shown)

Comments: 13 pages, 10 figures, accepted for publication in PASJ

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

We report photometric and spectroscopic observations and analysis of the 2019 superoutburst of TCP J21040470+4631129. This object showed a 9-mag superoutburst with early superhumps and ordinary superhumps, which are the features of WZ Sge-type dwarf novae. Five rebrightenings were observed after the main superoutburst. The spectra during the post-superoutburst stage showed the Balmer, He I and possible sodium doublet features. The mass ratio is derived as 0.0880(9) from the period of the superhump. During the third and fifth rebrightenings, growing superhumps and superoutbursts were observed, which have never been detected during a rebrightening phase among WZ Sge-type dwarf novae with multiple rebrightenings. To induce a superoutburst during the brightening phase, the accretion disk was needed to expand beyond the 3:1 resonance radius of the system again after the main superoutburst. These peculiar phenomena can be explained by the enhanced viscosity and large radius of the disk suggested by the higher luminosity and the presence of late-stage superhumps during the post-superoutburst stage, plus by more mass supply from the cool mass reservoir and/or from the secondary because of the enhanced mass transfer than those of other WZ Sge-type dwarf novae.

[25]  arXiv:2004.10510 [pdf, ps, other]

Title: An interstellar origin for high-inclination Centaurs

Authors: Fathi Namouni, Helena Morais

Comments: 10 pages, 4 figures

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

We investigate the possible origins of real high-inclination Centaurs and trans-neptunian objects using a high-resolution statistical search for stable orbits that simulates their evolution back in time to the epoch when planet formation ended 4.5 billion years in the past. The simulation is a precise orbit determination method that does not involve ad hoc initial conditions or assumptions such as those found in planetesimal disk relaxation models upon which their conclusions depend. It can therefore be used to independently test origin theories based on relaxation models by examining the past orbits of specific real objects. Here, we examined 17 multiple-opposition high-inclination Centaurs and the two polar trans-neptunian objects 2008 KV42 and (471325) 2011 KT19. The statistical distributions show that their orbits were nearly polar 4.5 Gyr in the past, and were located in the scattered disk and inner Oort cloud regions. Early polar inclinations cannot be accounted for by current Solar system formation theory as the early planetesimal system must have been nearly flat in order to explain the low-inclination asteroid and Kuiper belts. Furthermore, the early scattered disk and inner Oort cloud regions are believed to have been devoid of Solar system material as the planetesimal disk could not have extended far beyond Neptune's current orbit in order to halt the planet's outward migration. The nearly polar orbits of high-inclination Centaurs 4.5 Gyr in the past therefore indicate their probable early capture from the interstellar medium.

[26]  arXiv:2004.10540 [pdf, ps, other]

Title: Primordial Intermediate Mass Black Holes as Dark Matter

Authors: Paul H. Frampton

Comments: 11 pages LaTeX. Contribution to Proceedings of the 8th International Conference on New Frontiers in Physics (ICNFP-2019), Conference Center of the Orthodox Academy of Crete (OAC), Kolymbari, Crete, Greece. August 21-29, 2019. arXiv admin note: substantial text overlap with arXiv:1705.04373

Subjects: Astrophysics of Galaxies (astro-ph.GA); High Energy Physics - Phenomenology (hep-ph)

Among particle theory candidates for the dark matter constituents. axions and WIMPs are the most popular. In this talk we discuss these then focus on our preferred astrophysical candidate, the Primordial Intermediate Mass Black Holes in the acronym $DM=PIMBHs$. The earliest experimental confirmation may come from microlensing of the Magellanic Clouds at the LSST 8m telescope in the mid-2020s, or possibly a few years earlier in 2021 from work being pursued, using DECam data from the smaller Blanco 4m tescope, at LLNL.

[27]  arXiv:2004.10552 [pdf, other]

Title: The curious activity in the nucleus of NGC 4151: jet interaction causing variability?

Authors: D. R. A. Williams (1 and 2), R. D. Baldi (2, 4 and 5), I. M. McHardy (2), R. J. Beswick (3), F. Panessa (5), D. May (6), J. Moldón (3 and 7), M. K. Argo (3 and 8), G. Bruni (5), B. T. Dullo (9), J. H. Knapen (10, 11 and 12), E. Brinks (13), D. M. Fenech (14), C. G. Mundell (15), T. W. B. Muxlow (3), M. Pahari (2), J. Westcott (13) ((1) University of Oxford, UK, (2) University of Southampton, UK, (3) Jodrell Bank Centre for Astrophysics, University of Manchester, UK, (4) Universitá degli Studi di Torino, (5) INAF Roma, Italy, (6) Universidade de São Paulo, Brazil,(7) Instituto de Astrofísica de Andalucía (IAA, CSIC), Spain, (8) Jeremiah Horrocks Institute University of Central Lancashire, UK, (9) Universidad Complutense de Madrid, Spain, (10) Instituto de Astrofísica de Canarias, Spain, (11) Universidad de La Laguna, Spain, (12) Liverpool John Moores University, UK, (13) University of Hertfordshire, (14) Astrophysics Group, Cavendish Laboratory, UK, (15) University of Bath, UK)

Comments: 9 pages, 3 figures, 1 table, accepted to MNRAS

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

A key characteristic of many active galactic nuclei (AGN) is their variability, but its origin is poorly understood, especially in the radio domain. Williams et al. (2017) reported a ~50 per cent increase in peak flux density of the AGN in the Seyfert galaxy NGC 4151 at 1.5 GHz with the e-MERLIN array. We present new high resolution e-MERLIN observations at 5 GHz and compare these to archival MERLIN observations to investigate the reported variability. Our new observations allow us to probe the nuclear region at a factor three times higher-resolution than the previous e-MERLIN study. We separate the core component, C4, into three separate components: C4W, C4E and X. The AGN is thought to reside in component C4W, but this component has remained constant between epochs within uncertainties. However, we find that the Eastern-most component, C4E, has increased in peak flux density from 19.35$\pm$1.10 to 37.09$\pm$1.86 mJy/beam, representing a 8.2 sigma increase on the MERLIN observations. We attribute this peak flux density increase to continued interaction between the jet and the emission line region (ELR), observed for the first time in a low-luminosity AGN such as NGC 4151. We identify discrete resolved components at 5 GHz along the jet axis, which we interpret as areas of jet-ELR interaction.

[28]  arXiv:2004.10579 [pdf, other]

Title: $K2$ Ultracool Dwarfs Survey. VI. White light superflares observed on an L5 dwarf and flare rates of L dwarfs

Authors: Rishi R. Paudel, John E. Gizis, D. J. Mullan, Peter K. G. Williams, Adam J. Burgasser, Sarah J. Schmidt

Comments: 12 pages, 4 figures, accepted for publication in MNRAS

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

Kepler K2 long cadence data are used to study white light flares in a sample of 45 L dwarfs. We identified 11 flares on 9 L dwarfs with equivalent durations of (1.3 - 198) hr and total (UV/optical/IR) energies of $\geq$0.9 $\times$ 10$^{32}$ erg. Two superflares with energies of $>$10$^{33}$ erg were detected on an L5 dwarf: this is the coolest object so far on which flares have been identified. The larger superflare on this L5 dwarf has an energy of 4.6$\times$ 10$^{34}$ ergs and an amplitude of $>$300 times the photospheric level: so far, this is the largest amplitude flare detected by the $Kepler/K2$ mission. The next coolest star on which we identified a flare was an L2 dwarf: 2MASS J08585891+1804463. Combining the energies of all the flares which we have identified on 9 L dwarfs with the total observation time which was dedicated by $Kepler$ to all 45 L dwarfs, we construct a composite flare frequency distribution (FFD). The FFD slope is quite shallow (-0.51$\pm$0.17), consistent with earlier results reported by Paudel et al. (2018) for one particular L0 dwarf, for which the FFD slope was found to be -0.34. Using the composite FFD, we predict that, in early and mid-L dwarfs, a superflare of energy 10$^{33}$ erg occurs every 2.4 years and a superflare of energy 10$^{34}$ erg occurs every 7.9 years. Analysis of our L dwarf flares suggests that magnetic fields of $\geq$0.13-1.3 kG are present on the stellar surface: such fields could suppress Type II radio bursts.

[29]  arXiv:2004.10591 [pdf, other]

Title: Search for magnetically-induced signatures in the arrival directions of ultra-high-energy cosmic rays measured at the Pierre Auger Observatory

Authors: The Pierre Auger Collaboration: A. Aab, P. Abreu, M. Aglietta, J.M. Albury, I. Allekotte, A. Almela, J. Alvarez Castillo, J. Alvarez-Muñiz, R. Alves Batista, G.A. Anastasi, L. Anchordoqui, B. Andrada, S. Andringa, C. Aramo, P.R. Araújo Ferreira, H. Asorey, P. Assis, G. Avila, A.M. Badescu, A. Bakalova, A. Balaceanu, F. Barbato, R.J. Barreira Luz, K.H. Becker, J.A. Bellido, C. Berat, M.E. Bertaina, X. Bertou, P.L. Biermann, T. Bister, J. Biteau, A. Blanco, J. Blazek, C. Bleve, M. Boháčová, D. Boncioli, C. Bonifazi, L. Bonneau Arbeletche, N. Borodai, A.M. Botti, J. Brack, T. Bretz, F.L. Briechle, P. Buchholz, A. Bueno, S. Buitink, M. Buscemi, K.S. Caballero-Mora, L. Caccianiga, L. Calcagni, A. Cancio, F. Canfora, I. Caracas, J.M. Carceller, R. Caruso, A. Castellina, et al. (318 additional authors not shown)

Comments: Submitted for publication in JCAP

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

We search for signals of magnetically-induced effects in the arrival directions of ultra-high-energy cosmic rays detected at the Pierre Auger Observatory. We apply two different methods. One is a search for sets of events that show a correlation between their arrival direction and the inverse of their energy, which would be expected if they come from the same point-like source, they have the same electric charge and their deflection is relatively small and coherent. We refer to these sets of events as "multiplets". The second method, called "thrust", is a principal axis analysis aimed to detect the elongated patterns in a region of interest. We study the sensitivity of both methods using a benchmark simulation and we apply them to data in two different searches. The first search is done assuming as source candidates a list of nearby active galactic nuclei and starburst galaxies. The second is an all-sky blind search. We report the results and we find no statistically significant features. We discuss the compatibility of these results with the indications on the mass composition inferred from data of the Pierre Auger Observatory.

[30]  arXiv:2004.10607 [pdf, other]

Title: CLASS-PT: non-linear perturbation theory extension of the Boltzmann code CLASS

Authors: Anton Chudaykin, Mikhail M. Ivanov, Marko Simonović

Comments: 48 pages, 9 figures. The code and custom-built BOSS likelihoods are available at this https URL and this https URL

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

We present a new open-source code that calculates one-loop power spectra and cross spectra for matter fields and biased tracers in real and redshift space. These spectra incorporate all ingredients required for a direct application to data: non-linear bias and redshift-space distortions, infra-red resummation, counterterms, and the Alcock-Paczynski effect. Our code is based on the Boltzmann solver CLASS and inherits its advantageous properties: user friendliness, ease of modification, high speed, and simple interface with other software. We present detailed descriptions of the theoretical model, the code structure, approximations, and accuracy tests. A typical end-to-end run for one cosmology takes 0.3 seconds, which is sufficient for Markov Chain Monte Carlo parameter extraction. As an example, we apply the code to the Baryon Oscillation Spectroscopic Survey (BOSS) data and infer cosmological parameters from the shape of the galaxy power spectrum.

[31]  arXiv:2004.10611 [pdf, ps, other]

Title: Radial-velocity variations due to meridional flows in the Sun and solar-type stars: impact on exoplanet detectability

Authors: Nadège Meunier, Anne-Marie Lagrange

Comments: Accepted in Astronomy and Astrophysics

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

Stellar variability due to magnetic activity and flows at different spatial scales strongly impacts radial velocities. This variability is seen as oscillations, granulation, supergranulation, and meridional flows. The effect of this latter process is poorly known but could affect exoplanet detectability. We aim to quantify its amplitude when integrated over the disc and its temporal variability, first for the Sun, seen with different inclinations, and then for other solar-type stars. We used long time series of solar latitudinal meridional circulation to reconstruct its integrated contribution. We then used scaling laws from HD simulations relating the amplitude of the meridional flow variability with stellar mass and rotation rate to estimate the typical amplitude expected for other solar-type stars. We find typical rms of the order of 0.5-0.7 m/s (edge-on) and 1.2-1.7 m/s (pole-on) for the Sun, with a minimal jitter for an inclination of 45-55 deg. This is significant compared to other stellar activity contributions and is much larger than the radial-velocity signal of the Earth. The variability is strongly related to the activity cycle. Extension to other solar-type stars shows that the variability due to meridional flows is dominated by the amplitude of the cycle of those stars. The meridional flow contribution sometimes represents a high fraction of the convective blueshift inhibition signal, especially for quiet, low-mass stars. Our study shows that these meridional flows could be critical for exoplanet detection. Low inclinations are more impacted than edge-on configurations, but these latter still exhibit significant variability. Meridional flows also degrade the correlation between radial velocities due to convective blueshift inhibition and chromospheric activity indicators. This will make the correction from this signal challenging for stars with no multi-cellular patterns.

[32]  arXiv:2004.10644 [pdf, other]

Title: Gamma-Ray Absorption from The Cosmic Lyman Continuum Background

Authors: Matthew A. Malkan, Sean T. Scully, Floyd W. Stecker

Comments: 20 pages, 9 figures, submitted to Astrophysical Journal

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

Until recently, it was assumed that the diffuse extragalactic background light (EBL) in the FUV has a sharp and complete cut-off at energies above the Lyman limit. However, newly discovered extreme emission line starburst galaxies (EELGs) and other galaxies with substantial escape fractions of EUV photons in the Lyman continuum (LyC) region are increasingly common at high redshifts. The recent observations indicate that many more LyC photons at high redshifts escape from such galaxies into intergalactic space than was previously suspected. They are probably the major cause of reionization of the intergalactic medium. In this paper we estimate the contribution of these hitherto unconsidered EUV photons from EELGs at all redshifts to the (EBL), and their subsequent effect on the absorption of extragalactic high energy $\gamma$-rays. For the more distant $\gamma$-ray sources, particularly at $z \ge 3$, the intergalactic opacity above a few GeV is significantly higher than previously estimated. We calculate the results of this increased opacity on observed $\gamma$-ray spectra, which produces a high-energy turnover starting at lower energies than previously thought, and a gradual spectral steepening that may also be observable.

[33]  arXiv:2004.10665 [pdf, other]

Title: A Supernova Shock Break-out Candidate at z=0.092 in XMM-Newton Archival Data

Authors: G. Novara, P. Esposito, A. Tiengo, G. Vianello, R. Salvaterra, A. Belfiore, A. De Luca, P. D'Avanzo, J. Greiner, M. Scodeggio, S. Rosen, C. Delvaux, E. Pian, S. Campana, G. Lisini, S. Mereghetti

Comments: 11 pages, 6 figures; submitted to ApJ on February 21, 2020

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

During a search for X-ray transients in the XMM-Newton archive within the EXTraS project, we discovered a new X-ray source that is detected only during a ~5 min interval of a ~21 h-long observation performed on 2011 June 21 (EXMM 023135.0-603743, probability of a random Poissonian fluctuation: ~$1.4\times10^{-27}$). With dedicated follow-up observations, we found that its position is consistent with a star-forming galaxy (SFR = 1-2 $M_\odot$ yr$^{-1}$) at redshift $z=0.092\pm0.003$ ($d=435\pm15$ Mpc). At this redshift, the energy released during the transient event was $2.8\times10^{46}$ erg in the 0.3-10 keV energy band (in the source rest frame). The luminosity of the transient, together with its spectral and timing properties, make EXMM 023135.0-603743 a gripping analog to the X-ray transient associated to SN 2008D, which was discovered during a Swift/XRT observation of the nearby ($d=27$ Mpc) supernova-rich galaxy NGC 2770. We interpret the XMM-Newton event as a supernova shock break-out and prove that our serendipitous discovery is compatible with the rate of core-collapse supernovae derived from optical observations.

[34]  arXiv:2004.10668 [pdf]

Title: VENUS: a new apparatus to investigate surface chemistry routes leading to complex organic molecules in space

Authors: Emanuele Congiu, Abdellahi Sow, Thanh Nguyen, Saoud Baouche, François Dulieu

Comments: 35 pages, 18 figures

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

A multi-beam ultra-high vacuum apparatus is presented. In this article we describe the design and construction of a new laboratory astrophysics experiment -- VErs de NoUvelles Synth\`eses (VENUS) -- that recreates the solid-state non-energetic formation conditions of complex organic molecules in dark clouds and circumstellar environments. The novel implementation of four operational differentially-pumped beam lines will be used to determine the feasibility and the rates for the various reactions that contribute to formation of molecules containing more than six atoms. Data are collected by means of Fourier transform infrared spectroscopy and quadrupole mass spectrometry. The gold-coated sample holder reaches temperatures between 7 and 400 K. The apparatus was carefully calibrated and the acquisition system was developed to ensure that experimental parameters are recorded as accurately as possible. A great effort has been made to have the beam lines converge towards the sample. Experiments have been developed to check the beam alignment using reacting systems of neutral species (NH$_3$, H$_2$CO). Preliminary original results were obtained for the NO+H system, which shows that chemistry occurs only in the very first outer layer of the deposited species, that is the chemical layer and the physical layer coincide. This article illustrates the characteristics, performance, and future potential of the new apparatus in view of the forthcoming launch of the James Webb Space Telescope. We show that VENUS will have a major impact through its contributions to surface science and astrochemistry.

[35]  arXiv:2004.10678 [pdf, other]

Title: Efficient modeling of correlated noise II. A flexible noise model with fast and scalable methods

Authors: J.-B. Delisle, N. Hara, D. Ségransan

Comments: Accepted in A&A

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

Correlated noise affects most astronomical datasets and to neglect accounting for it can lead to spurious signal detections, especially in low signal-to-noise conditions, which is often the context in which new discoveries are pursued. For instance, in the realm of exoplanet detection with radial velocity time series, stellar variability can induce false detections. However, a white noise approximation is often used because accounting for correlated noise when analyzing data implies a more complex analysis. Moreover, the computational cost can be prohibitive as it typically scales as the cube of the dataset size.
For some restricted classes of correlated noise models, there are specific algorithms that can be used to help bring down the computational cost. This improvement in speed is particularly useful in the context of Gaussian process regression, however, it comes at the expense of the generality of the noise model.
Here, we present the S+LEAF noise model, which allows us to account for a large class of correlated noises with a linear scaling of the computational cost with respect to the size of the dataset. The S+LEAF model includes, in particular, mixtures of quasiperiodic kernels and calibration noise. This efficient modeling is made possible by a sparse representation of the covariance matrix of the noise and the use of dedicated algorithms for matrix inversion, solving, determinant computation, etc.
We applied the S+LEAF model to reanalyze the HARPS radial velocity time series of HD 136352. We illustrate the flexibility of the S+LEAF model in handling various sources of noise. We demonstrate the importance of taking correlated noise into account, and especially calibration noise, to correctly assess the significance of detected signals.
We provide an open-source implementation of the S+LEAF model, available at https://gitlab.unige.ch/jean-baptiste.delisle/spleaf.

[36]  arXiv:2004.10683 [pdf, other]

Title: Probing Flavor Structure of Cosmic Ray $e^\mp$ Spectrum and Implications for Indirect Dark Matter Searches

Authors: Shao-Feng Ge, Hong-Jian He, Yu-Chen Wang, Qiang Yuan

Comments: 35 pages, 9 Figs (21 plots), 8 Tables

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

Measuring high energy cosmic ray electrons/positrons (CRE) provides important means for probing the nearby galactic sources and for the dark matter (DM) indirect detection. In this work, we perform a systematical analysis of the flavor structure of DM annihilations into charged leptons based on the cosmic ray CRE spectra measured by DAMPE, Fermi-LAT, AMS-02, and CALET experiments. We study the annihilations of possible TeV scale DM particles in a nearby subhalo, which is proposed to explain the possible peak-like structure of the DAMPE CRE data. We pay special attention to the possible non-resonant excess (besides the possible peak-like structure) and demonstrate that such non-resonant excess can mainly arise from the decay of muons produced by the DM annihilations in the subhalo. With these we study the flavor composition of the lepton final states of $\chi\chi \to e^+e^-, \mu^+\mu^-, \tau^+\tau^-$ by fitting the CRE data. We further analyze the constraints on the lepton flavor composition using the Fermi-LAT $\gamma$-ray measurements. We find that the flavor composition (favored by the CRE data) is consistent with the Fermi-LAT data at relatively low Galactic latitudes, while the fraction of the final state $\tau^\pm$ is severely bounded.

[37]  arXiv:2004.10702 [pdf, other]

Title: Gravitational wave constraints on the observable inflation

Authors: Erwin H. Tanin, Tommi Tenkanen

Comments: 5 pages, 1 figure

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

Gravitational waves (GW) produced in the early Universe contribute to the number of relativistic degrees of freedom, $N_{\rm eff}$, during Big Bang Nucleosynthesis (BBN). By using the constraints on $N_{\rm eff}$, we present a new bound on how much the observable Universe could have expanded during cosmic inflation. The new bound is roughly four orders of magnitude more stringent than previous bounds. We also discuss the sensitivities of the current and planned GW observatories such as LIGO and LISA, and show that the constraints they could impose are always less stringent than the BBN bound.

[38]  arXiv:2004.10709 [pdf, other]

Title: Ionization Yield in Silicon for eV-Scale Electron-Recoil Processes

Authors: Karthik Ramanathan, Noah Kurinksy

Comments: 13 pages, 13 figures

Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); High Energy Physics - Experiment (hep-ex); Data Analysis, Statistics and Probability (physics.data-an); Instrumentation and Detectors (physics.ins-det)

The development of single charge resolving, macroscopic silicon detectors has opened a window into rare processes at the O(eV) scale. In order to reconstruct the energy of a given event, or model the charge signal obtained for a given amount of energy absorbed by the electrons in a detector, an accurate charge yield model is needed. In this paper we review existing measurements of charge yield in Silicon, focusing in particular on the region below 1 keV. We highlight a calibration gap between 12-50 eV (referred to as the "UV-gap") and employ a phenomenological model of impact ionization to explore the likely charge yield in this energy regime. Finally, we explore the impact of variations in this model on a test case, that of dark matter scattering off electrons, to illustrate the scientific impact of uncertainties in charge yield.

[39]  arXiv:2004.10735 [pdf, other]

Title: Laboratory evidence for asymmetric accretion structure upon slanted matter impact in young stars

Authors: K. Burdonov, G. Revet, R. Bonito, C. Argiroffi, J. Beard, S. Bolanos, M. Cerchez, S.N. Chen, A. Ciardi, G. Espinosa, E. Fillipov, S. Pikuz, R. Rodriguez, M. Smid, M. Starodubtsev, O. Willi, S. Orlando, J. Fuchs

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

Investigating in the laboratory the process of matter accretion onto forming stars through scaled experiments is important in order to better understand star and planetary systems formation and evolution. Such experiments can indeed complement observations by providing access to the processes with spatial and temporal resolution. A first step has been made in [G. Revet et al., Science Advances 3, e1700982 (2017), arXiv:1708.02528]. in allowing such investigations. It revealed the existence of a two components stream: a hot shell surrounding a cooler inner stream. The shell was formed by matter laterally ejected upon impact and refocused by the local magnetic field. That laboratory investigation was limited tonormal incidence impacts. However, in young stellar objects, complex structure of magnetic fields causes variability of the incidentangles of the accretion columns. This led us to undertake an investigation, using laboratory plasmas, of the consequence of having a slanted accretion impacting a young star. Here we use high power laser interactions and strong magnetic field generation in the laboratory, complemented by numerical simulations, to study the asymmetry induced upon accretion structures when columns of matter impact the surface of young stars with an oblique angle. Compared to the scenario where matter accretes normal to the star surface, we observe strongly asymmetric plasma structure, strong lateral ejecta of matter, poor confinement of the accreted material and reduced heating compared to the normal incidence case. Thus, slanted accretion is a configuration that seems to be capable of inducing perturbations of the chromosphere and hence possibly influence the level of activity of the corona.

Cross-lists for Thu, 23 Apr 20

[40]  arXiv:2004.01669 (cross-list from hep-ph) [pdf, other]

Title: How to suppress exponential growth -- on the parametric resonance of photons in an axion background

Authors: Ariel Arza, Thomas Schwetz, Elisa Todarello

Comments: 34 pages, 10 figures

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

Axion--photon interactions can lead to an enhancement of the electromagnetic field by parametric resonance in the presence of a cold axion background, for modes with a frequency close to half the axion mass. In this paper, we study the role of the axion momentum dispersion as well as the effects of a background gravitational potential, which can detune the resonance due to gravitational redshift. We show, by analytical as well as numerical calculations, that the resonance leads to an exponential growth of the photon field only if (a) the axion momentum spread is smaller than the inverse resonance length, and (b) the gravitational detuning distance is longer than the resonance length. For realistic parameter values, both effects strongly suppress the resonance and prevent the exponential growth of the photon field. In particular, the redshift due to the gravitational potential of our galaxy prevents the resonance from developing for photons in the observable frequency range, even assuming that all the dark matter consists of a perfectly cold axion condensate. For axion clumps with masses below $\sim 10^{-13}\, M_\odot$, the momentum spread condition is more restrictive, whereas, for more massive clumps, the redshift condition dominates.

[41]  arXiv:2004.10218 (cross-list from physics.ed-ph) [pdf, other]

Title: Making Science Personal: Inclusivity-Driven Design for General-Education Courses

Authors: Christine O'Donnell, Edward E. Prather, Peter Behroozi

Comments: 17 pages, 1 figure, 3 tables. Accepted for publication in the Journal of College Science Teaching

Subjects: Physics Education (physics.ed-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO)

General-education college astronomy courses offer instructors both a unique audience and a unique challenge. For many students, such a course may be their first time encountering a standalone astronomy class, and it is also likely one of the last science courses they will take. Thus, in a single semester, primary course goals often include both imparting knowledge about the Universe and giving students some familiarity with the processes of science. In traditional course environments, students often compartmentalize information into separate "life files" and "course files" rather than integrating information into a coherent framework. The astronomy course created through this project, taught at the University of Arizona in Spring 2019, was designed around inclusivity-driven guiding principles that help students engage with course content in ways that are meaningful, relevant, and accessible. Our course bridges the gap between students' "life" and "course files", encourages and respects diverse points of view, and empowers students to connect course content with their personal lives and identities. In this paper, we provide insight into the guiding principles that informed our course design and share research results on the effectiveness of the instructional strategies and assessment techniques implemented in the course.

[42]  arXiv:2004.10309 (cross-list from nucl-th) [pdf, other]

Title: Short-range correlation effects on the neutron star cooling

Authors: Lucas A. Souza, Rodrigo Negreiros, Mariana Dutra, Débora P. Menezes, Odilon Lourenço

Comments: 7 pages, 6 figures

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

Short range correlations (SRC) have been known to be an important aspect of nuclear theory for some time. Recent works have re-ignited interest on this topic, particularly due to the fact that it has recently been demonstrated that SRC may be responsible for breaking pairing gaps in nuclear matter. In this work we revisit the concept of SRC for beta equilibrated matter in neutron stars. We construct two equivalent models, with and without SRC and proceed to investigate the thermal evolution of stars described by such models. We show that SRC play a major role in the thermal evolution of neutron stars. It will be shown that while the SRC largely leaves the macroscopic properties of the star unaltered, it significantly alters the proton fraction, thus leading to an early onset of the direct Urca (DU) process, which in turns leads to stars exhibiting much faster cooling.

[43]  arXiv:2004.10542 (cross-list from physics.comp-ph) [pdf, other]

Title: Systematic construction of upwind constrained transport schemes for MHD

Authors: Andrea Mignone, Luca Del Zanna

Comments: 28 pages, 16 figures

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

The constrained transport (CT) method reflects the state of the art numerical technique for preserving the divergence-free condition of magnetic field to machine accuracy in multi-dimensional MHD simulations performed with Godunov-type, or upwind, conservative codes. The evolution of the different magnetic field components, located at zone interfaces using a staggered representation, is achieved by calculating the electric field components at cell edges, in a way that has to be consistent with the Riemann solver used for the update of cell-centered fluid quantities at interfaces. Albeit several approaches have been undertaken, the purpose of this work is, on the one hand, to compare existing methods in terms of robustness and accuracy and, on the other, to extend the upwind contrained transport (UCT) method by Londrillo & Del Zanna (2004) and Del Zanna et al. (2007) for the systematic construction of new averaging schemes using the information available from 1D Riemann solvers. Our results are presented here in the context of second-order schemes for classical MHD, but they can be easily generalized to higher than second order schemes, either based on finite volumes or finite differences, and to other physical systems retaining the same structure of the equations, such as that of relativistic or general relativistic MHD.

[44]  arXiv:2004.10684 (cross-list from gr-qc) [pdf, other]

Title: Emergence of classical behavior in the early universe

Authors: Abhay Ashtekar, Alejandro Corichi, Aruna Kesavan

Comments: 38 pages; 3 Figures. The first and the last sections provide a succinct summary of the motivation results

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

We investigate three issues that have been discussed in the context of inflation: Fading of the importance of quantum non-commutativity; the phenomenon of quantum squeezing; and the ability to approximate the quantum state by a distribution function on the classical phase space. In the standard treatments, these features arise from properties of mode functions of quantum fields in (near) de Sitter space-time. Therefore, the three notions are often assumed to be essentially equivalent, representing different facets of the same phenomenon. We analyze them in general Friedmann-Lemaitre- Robertson-Walker space-times, through the lens of geometric structures on the classical phase space. The analysis shows that: (i) inflation does not play an essential role; classical behavior can emerge much more generally; (ii) the three notions are conceptually distinct; classicality can emerge in one sense but not in another; and, (iii) the third notion is realized in a surprisingly strong sense; there is exact equality between completely general $n$-point functions in the classical theory and those in the quantum theory, provided the quantum operators are Weyl ordered. These features arise already for linear cosmological perturbations by themselves: considerations such as mode-mode coupling, decoherence, and measurement theory --although important in their own right-- are not needed for emergence of classical behavior in any of the three senses discussed. Generality of the results stems from the fact that they can be traced back to geometrical structures on the classical phase space, available in a wide class of systems. Therefore, this approach may also be useful in other contexts.

[45]  arXiv:2004.10743 (cross-list from hep-ph) [pdf, other]

Title: Light Dark Photon Dark Matter from Inflation

Authors: Yuichiro Nakai, Ryo Namba, Ziwei Wang

Comments: 24 pages, 2 figures

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

We discuss the possibility of producing a light dark photon dark matter through a coupling between the dark photon field and the inflaton. The dark photon with a large wavelength is efficiently produced due to the inflaton motion during inflation and becomes non-relativistic before the time of matter-radiation equality. We compute the amount of production analytically. The correct relic abundance is realized with a dark photon mass extending down to $10^{-21} \, \rm eV$.

Replacements for Thu, 23 Apr 20

[46]  arXiv:1905.04686 (replaced) [pdf, other]

Title: A Unique Multi-Messenger Signal of QCD Axion Dark Matter

Authors: Thomas D. P. Edwards, Marco Chianese, Bradley J. Kavanagh, Samaya M. Nissanke, Christoph Weniger

Comments: 5 pages, 3 figures. Appendix added with additional figures. Updated to published version

Journal-ref: Phys. Rev. Lett. 124, 161101 (2020)

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

[47]  arXiv:1905.09258 (replaced) [pdf, other]

Title: Production and Backreaction of Fermions from Axion-$SU(2)$ Gauge Fields during Inflation

Authors: Leila Mirzagholi, Azadeh Maleknejad, Kaloian D. Lozanov

Comments: Matches version accepted for publication in PRD

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

[48]  arXiv:1905.13486 (replaced) [pdf, other]

Title: Baryon-Dark matter interaction in presence of magnetic fields in light of EDGES signal

Authors: Jitesh R. Bhatt, Pravin Kumar Natwariya, Alekha C. Nayak, Arun Kumar Pandey

Comments: 9 pages and 6 figures

Journal-ref: Eur. Phys. J. C 80, 334 (2020)

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

[49]  arXiv:1907.00916 (replaced) [pdf, other]

Title: Mapping the relativistic electron gas temperature across the sky

Authors: Mathieu Remazeilles, Jens Chluba

Comments: 17 pages, 18 figures, updated to match version accepted by MNRAS

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

[50]  arXiv:1907.02740 (replaced) [pdf, other]

Title: Connecting ANITA Anomalous Events to a Non-thermal Dark Matter Scenario

Authors: Debasish Borah, Arnab Dasgupta, Ujjal Kumar Dey, Gaurav Tomar

Comments: 21 pages, 6 figures, accepted for publication in Physical Review D

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

[51]  arXiv:1907.02838 (replaced) [pdf, other]

Title: Weak equivalence principle, swampland and $H_0$ tension with fast single radio bursts FRB 180924 and FRB 190523

Authors: Deng Wang, Zhaozhou Li, Jiajun Zhang

Comments: 7 pages, 2 figures, references added, accepted in Physics of the Dark Universe

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

[52]  arXiv:1907.02972 (replaced) [pdf, other]

Title: Dynamical Properties of Molecular-forming Gas Clumps in Galaxies at the Epoch of Reionization

Authors: T. K. Daisy Leung (Cornell, Flatiron CCA), Andrea Pallottini (Centro Fermi, SNS), Andrea Ferrara (SNS, Kavli IPMU), Mordecai-Mark Mac Low (Flatiron CCA, AMNH)

Comments: 16 pages, 10 figures, ApJ accepted

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

[53]  arXiv:1907.06652 (replaced) [pdf, other]

Title: Cataloging Accreted Stars within Gaia DR2 using Deep Learning

Authors: Bryan Ostdiek, Lina Necib, Timothy Cohen, Marat Freytsis, Mariangela Lisanti, Shea Garrison-Kimmel, Andrew Wetzel, Robyn E. Sanderson, Philip F. Hopkins

Comments: v1: 24 pages and 13 Figures + 4 appendices, v2: Journal version, fixed bug resulting in incorrect final catalog scores, updated plots, conclusions unchanged

Journal-ref: A&A 636, A75 (2020)

Subjects: Astrophysics of Galaxies (astro-ph.GA); High Energy Physics - Phenomenology (hep-ph); Machine Learning (stat.ML)

[54]  arXiv:1909.04262 (replaced) [pdf, ps, other]

Title: ALMA Observations of Giant Molecular Clouds in M33 I: Resolving Star Formation Activities in the Giant Molecular Filaments Possibly Formed by a Spiral Shock

Authors: Kazuki Tokuda, Kazuyuki Muraoka, Hiroshi Kondo, Atsushi Nishimura, Tomoka Tosaki, Sarolta Zahorecz, Sachiko Onodera, Rie E. Miura, Kazufumi Torii, Nario Kuno, Shinji Fujita, Hidetoshi Sano, Toshikazu Onishi, Kazuya Saigo, Yasuo Fukui, Akiko Kawamura, Kengo Tachihara

Comments: 12 pages, 5 figures, Accepted for publication in ApJ

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

[55]  arXiv:1909.07742 (replaced) [pdf, other]

Title: The clustering of the SDSS-IV extended Baryon Oscillation Spectroscopic Survey DR14 LRG sample: structure growth rate measurement from the anisotropic LRG correlation function in the redshift range 0.6 < z < 1.0

Authors: M. Icaza-Lizaola, M. Vargas-Magaña, S. Fromenteau, S. Alam, B. Camacho, H. Gil-Marin, R. Paviot, Ashley Ross, Donald P. Schneider, Jeremy Tinker, Yuting Wang, Cheng Zhao, Abhishek Prakash, G.Rossi, Gong-Bo Zhao, Irene Cruz-Gonzalez, Axel de la Macorra

Comments: Accepted on the 5th December 2019, 28 pages,27 figures

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

[56]  arXiv:1910.04592 (replaced) [pdf, ps, other]

Title: Luminous Type II supernovae for their low expansion velocities

Authors: Ó. Rodríguez, G. Pignata, J. P. Anderson, T. J. Moriya, A. Clocchiatti, F. Förster, J. L. Prieto, M. M. Phillips, C. R. Burns, C. Contreras, G. Folatelli, C. P. Gutiérrez, M. Hamuy, N. I. Morrell, M. D. Stritzinger, N. B. Suntzeff, S. Benetti, E. Cappellaro, N. Elias-Rosa, A. Pastorello, M. Turatto, J. Maza, R. Antezana, R. Cartier, L. González, J. B. Haislip, V. Kouprianov, P. López, S. Marchi-Lasch, D. Reichart

Comments: 20 pages, 15 figures, Accepted for publication to MNRAS

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

[57]  arXiv:1910.05335 (replaced) [pdf, other]

Title: Looks can be deceiving: underestimating the age of single white dwarfs due to binary mergers

Authors: Karel D. Temmink, Silvia Toonen, Emmanouil Zapartas, Stephen Justham, Boris T. Gänsicke

Comments: 16 pages, 14 figures. Published in A&A

Journal-ref: A&A 636, A31 (2020)

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

[58]  arXiv:1910.05748 (replaced) [pdf, other]

Title: Measurements of B-mode Polarization of the Cosmic Microwave Background from 500 Square Degrees of SPTpol Data

Authors: J.T. Sayre, C. L. Reichardt, J. W. Henning, P. A. R. Ade, A. J. Anderson, J. E. Austermann, J. S. Avva, J. A. Beall, A. N. Bender, B. A. Benson, F. Bianchini, L. E. Bleem, J. E. Carlstrom, C. L. Chang, H. C. Chiang, R. Citron, C. Corbett Moran, T. M. Crawford, A. T. Crites, T. de Haan, M. A. Dobbs, W. Everett, J. Gallicchio, E. M. George, A. Gilbert, N. Gupta, N. W. Halverson, N. Harrington, G. C. Hilton, G. P. Holder, W. L. Holzapfel, J. D. Hrubes, N. Huang, J. Hubmayr, K. D. Irwin, L. Knox, A. T. Lee, D. Li, A. Lowitz, J. J. McMahon, S. S. Meyer, L. M. Mocanu, J. Montgomery, A. Nadolski, T. Natoli, J. P. Nibarger, G. Noble, V. Novosad, S. Padin, S. Patil, C. Pryke, J. E. Ruhl, B. R. Saliwanchik, K. K. Schaffer, C. Sievers, G. Smecher, A. A. Stark, C. Tucker, K. Vanderlinde, T. Veach, J. D. Vieira, et al. (4 additional authors not shown)

Comments: 16 pages, 4 figures, Submitted to PRD

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

[59]  arXiv:1910.14045 (replaced) [pdf, other]

Title: The Dragonfly Wide Field Survey. I. Telescope, Survey Design and Data Characterization

Authors: Shany Danieli, Deborah Lokhorst, Jielai Zhang, Allison Merritt, Pieter van Dokkum, Roberto Abraham, Charlie Conroy, Colleen Gilhuly, Johnny Greco, Steven Janssens, Jiaxuan Li, Qing Liu, Tim B. Miller, Lamiya Mowla

Comments: Accepted for publication in ApJ. This is the first paper in the series. Preliminary results from the survey are shown in figures 5-10

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

[60]  arXiv:1911.02979 (replaced) [pdf, other]

Title: Estimating trajectories of meteors: an observational Monte Carlo approach -- I. Theory

Authors: Denis Vida, Peter S. Gural, Peter G. Brown, Margaret Campbell-Brown, Paul Wiegert

Comments: Accepted for publication in MNRAS

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

[61]  arXiv:1911.05412 (replaced) [pdf, other]

Title: Magnetic fields in a hot dense neutrino plasma and the Gravitational Waves

Authors: Arun Kumar Pandey, Pravin Kumar Natwariya, Jitesh R Bhatt

Comments: 9 pages, 5 figures

Journal-ref: Phys. Rev. D 101, 023531 (2020)

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

[62]  arXiv:1912.02350 (replaced) [pdf, other]

Title: A Linear Formation Flying Astronomical Interferometer in Low Earth Orbit

Authors: Jonah T. Hansen, Michael J. Ireland

Comments: 12 Pages, 8 Figures, accepted for publication in Publications of the Astronomical Society of Australia

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

[63]  arXiv:1912.11629 (replaced) [pdf, other]

Title: Prospects for improving cosmological parameter estimation with gravitational-wave standard sirens from Taiji

Authors: Ze-Wei Zhao, Ling-Feng Wang, Jing-Fei Zhang, Xin Zhang

Comments: 12 pages, 8 figures; accepted for publication in Science Bulletin

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

[64]  arXiv:2001.05555 (replaced) [pdf, other]

Title: Probing the Influence of a Tachocline in Simulated M-Dwarf Dynamos

Authors: Connor P. Bice, Juri Toomre

Journal-ref: ApJ 893 107 (2020)

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

[65]  arXiv:2001.05677 (replaced) [pdf, other]

Title: Modeling the IRIS Lines During a Flare. I. The Blue-Wing Enhancement in the Mg II k Line

Authors: Jie Hong, Ying Li, M. D. Ding, Yu-Hao Zhou

Comments: Updated figures

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

[66]  arXiv:2001.06318 (replaced) [pdf, other]

Title: Comparing parametric and non-parametric velocity-dependent one-scale models for domain wall evolution

Authors: P. P. Avelino

Comments: 12 pages, 4 figures. Matches published version in JCAP. arXiv admin note: text overlap with arXiv:1910.07011

Journal-ref: JCAP 04 (2020) 012

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

[67]  arXiv:2002.02553 (replaced) [pdf, other]

Title: Orbit-induced spin precession as an origin of periodicity in periodically-repeating fast radio bursts

Authors: Huan Yang, Yuan-Chuan Zou

Comments: 11 pages, 4 figures

Journal-ref: ApJL 893 L31, 2020

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

[68]  arXiv:2002.04035 (replaced) [pdf, other]

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

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

Comments: 42 pages, 12 figures, accepted by JCAP, likelihoods available at this https URL

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

[69]  arXiv:2002.08486 (replaced) [pdf, other]

Title: The accuracy of post-processing nucleosynthesis

Authors: Eduardo Bravo

Comments: Accepted for MNRAS, 11 pages, 4 figures, 3 tables. Revised version after referee report, with quantitative changes in Table 2 and Figure 4

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

[70]  arXiv:2003.02273 (replaced) [pdf, other]

Title: Cosmological Bounds on sub-GeV Dark Vector Bosons from Electromagnetic Energy Injection

Authors: John Coffey, Lindsay Forestell, David E. Morrissey, Graham White

Comments: 36 pages 7 figures. Added citations and prepared for submission

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

[71]  arXiv:2003.04814 (replaced) [pdf, other]

Title: Dust Attenuation Curve for Local Subgalactic Star-forming Regions

Authors: Berzaf Berhane Teklu, Zesen Lin, Xu Kong, Enci Wang, Yulong Gao, Qing Liu, Ning Hu, Haiyang Liu

Comments: Accepted for publication in ApJ, updated to match the final version

Journal-ref: ApJ, 893, 94, 2020

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

[72]  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: Accepted for publication in A&A Letters. 5 pages, 2 figures and 4 tables

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

[73]  arXiv:2003.12426 (replaced) [pdf, other]

Title: The Chemical Evolution of Galaxy Clusters: Dissecting the Iron Mass Budget of the Intracluster Medium

Authors: Ang Liu, Paolo Tozzi, Stefano Ettori, Sabrina De Grandi, Fabio Gastaldello, Piero Rosati, Colin Norman

Comments: Accepted for publication in A&A

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

[74]  arXiv:2004.00401 (replaced) [pdf, other]

Title: Conspiratorial cosmology. II. The anthropogenic principle

Authors: Jörg P. Rachen, Ute G. Gahlings (Rautavistische Universität)

Comments: 8 pages, 1 figure. Accepted by Journal of Comparative Irrelevance (Letters) after minor language corrections and including a reference to a recent paper on coupled dark energy

Journal-ref: Journal of Comparative Irrelevance (Letters), Volume 42, CIA 231423 (2020)

Subjects: Popular Physics (physics.pop-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO)

[75]  arXiv:2004.02155 (replaced) [pdf, other]

Title: Hints of a Local Matter Underdensity or Modified Gravity in the Low $z$ Pantheon data

Authors: L. Kazantzidis, L. Perivolaropoulos

Comments: 18 pages, 13 figures, 2 Tables. References added, appendix added with discussion of systematic uncertainties. The mathematica files for the production of the figures can be downloaded from this https URL

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

[76]  arXiv:2004.05000 (replaced) [pdf, other]

Title: Cosmic spin and mass evolution of black holes and its impact

Authors: Dipanweeta Bhattacharyya, A. Mangalam (Indian Institute of Astrophysics)

Comments: 56 pages, 27 figures; accepted for publication in the Astrophysical Journal; v2: updated references, typos fixed, editorial changes

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

[77]  arXiv:2004.05296 (replaced) [pdf, other]

Title: Searching the Entirety of Kepler Data. II. Occurrence Rate Estimates for FGK Stars

Authors: Michelle Kunimoto, Jaymie M. Matthews

Comments: 31 pages, 14 figures, accepted for publication in The Astronomical Journal

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

[78]  arXiv:2004.09339 (replaced) [pdf, ps, other]

Title: Vacua in novel 4D Einstein-Gauss-Bonnet Gravity: pathology and instability?

Authors: Fu-Wen Shu

Comments: 6 pages, 1 figure

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

[79]  arXiv:2004.09359 (replaced) [pdf, other]

Title: A 4-6 GHz Radio Recombination Line Survey in the Milky Way

Authors: Hong-Ying Chen, Xi Chen, Jun-Zhi Wang, Zhi-Qiang Shen, Kai Yang

Comments: 24 pages, 19 figures

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

[80]  arXiv:2004.09555 (replaced) [pdf, other]

Title: The MUSTANG-2 Galactic Plane Survey (MGPS90) pilot

Authors: Adam Ginsburg, L. D. Anderson, Simon Dicker, Charles Romero, Brian Svoboda, Mark Devlin, Roberto Galván-Madrid, Remy Indebetouw, Hauyu Baobab Liu, Brian Mason, Tony Mroczkowski, W. P. Armentrout, John Bally, Crystal Brogan, Natalie Butterfield, Todd R. Hunter, Erik D. Reese, Erik Rosolowsky, Craig Sarazin, Yancy Shirley, Jonathan Sievers, Sara Stanchfield

Comments: Accepted to ApJS. Data publicly released, with links in paper. Reposted to fix missing figure labels

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

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