Astrophysics

New submissions

• New submissions
• Cross-lists
• Replacements

New submissions for Tue, 28 Apr 20

[1]  arXiv:2004.11911 [pdf, other]

Title: Feeding and feedback from little monsters: AGN in dwarf galaxies

Authors: M Mezcua

Comments: Proceedings of the IAU Symposium No. 359: Galaxy evolution and feedback across different environments. Editors: T. Storchi-Bergmann, R. Overzier, W. Forman \& R. Riffel

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

Detecting the seed black holes from which quasars formed is extremely challenging; however, those seeds that did not grow into supermassive should be found as intermediate-mass black holes (IMBHs) of 100-10$^5$ M$_{\odot}$ in local dwarf galaxies. The use of deep multiwavelength surveys has revealed that a population of actively accreting IMBHs (low-mass AGN) exists in dwarf galaxies at least out to $z\sim$3. The black hole occupation fraction of these galaxies suggests that the early Universe seed black holes formed from direct collapse of gas, which is reinforced by the possible flattening of the black hole-galaxy scaling relations at the low-mass end. This scenario is however challenged by the finding that AGN feedback can have a strong impact on dwarf galaxies, which implies that low-mass AGN in dwarf galaxies might not be the untouched relics of the early seed black holes. This has important implications for seed black hole formation models.

[2]  arXiv:2004.11912 [pdf, other]

Title: Predictions of the L[CII] -- SFR and [CII] Luminosity Function at the Epoch of Reionization

Authors: T. K. Daisy Leung (Flatiron CCA, Cornell), Karen P. Olsen (U Arizona), Rachel S. Somerville (Flatiron CCA, Rutgers), Romeel Dave (Edinburgh), Thomas R. Greve (UCL, DAWN Copenhagen), Christopher C. Hayward (Flatiron CCA), Desika Narayanan (U Florida, DAWN Copenhagen), Gergo Popping (ESO)

Comments: 17 pages, 13 figures, submitted to the ApJ

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

We present the first predictions for the $L_{\rm [CII]}$ - SFR relation and [CII] luminosity function (LF) in the Epoch of Reionization (EoR) based on cosmological hydrodynamics simulations using the SIMBA suite plus radiative transfer calculations via S\'IGAME. The sample consists of 11,137 galaxies covering halo mass $\log M_{\rm halo}\in$[9, 12.4] $M_\odot$, star formation rate SFR$\in$[0.01, 330] $M_\odot$ yr$^{-1}$, and metallicity $<Z_{\rm gas}>_{\rm SFR}\in$[0.1, 0.9] $Z_\odot$. The simulated $L_{\rm [CII]}$-SFR relation is consistent with the range observed, but with a spread of $\simeq$0.3 dex at the high end of SFR ($>$100 $M_\odot$ yr$^{-1}$) and $\simeq$0.6 dex at the lower end, and there is tension between our predictions and the values of $L_{\rm [CII]}$ above 10$^{8.5}$ $L_\odot$ observed in some galaxies reported in the literature. The scatter in the $L_{\rm [CII]}$-SFR relation is mostly driven by galaxy properties, such that at a given SFR, galaxies with higher molecular gas mass and metallicity have higher $L_{\rm [CII]}$. The [CII] LF predicted by SIMBA is consistent with the upper limits placed by the only existing untargeted flux-limited [CII] survey at the EoR (ASPECS) and those predicted by semi-analytic models. We compare our results with existing models and discuss differences responsible for the discrepant slopes in the $L_{\rm [CII]}$-SFR relatiion.

[3]  arXiv:2004.11913 [pdf, ps, other]

Title: Evaluating the impact of binary parameter uncertainty on stellar population properties

Authors: E. R. Stanway (1), A. A. Chrimes (1), J. J. Eldridge (2), H. F. Stevance (2). ((1) Warwick, UK, (2) Auckland, NZ)

Comments: 18 pages + appendix. Accepted for publication in MNRAS. Author's accepted version

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

Binary stars have been shown to have a substantial impact on the integrated light of stellar populations, particularly at low metallicity and early ages - conditions prevalent in the distant Universe. But the fraction of stars in stellar multiples as a function of mass, their likely initial periods and distribution of mass ratios are all known empirically from observations only in the local Universe. Each has associated uncertainties. We explore the impact of these uncertainties in binary parameters on the properties of integrated stellar populations, considering which properties and timescales are most susceptible to uncertainty introduced by binary fractions and whether observations of the integrated light might be sufficient to determine binary parameters. We conclude that the effects of uncertainty in the empirical binary parameter distributions are likely smaller than those introduced by metallicity and stellar population age uncertainties for observational data. We identify emission in the He II 1640 Angstrom emission line and continuum colour in the ultraviolet-optical as potential indicators of a high mass binary presence, although poorly constrained metallicity, dust extinction and degeneracies in plausible star formation history are likely to swamp any measurable signal.

[4]  arXiv:2004.11914 [pdf, other]

Title: Spin Evolution of Stellar-mass Black Hole Binaries in Active Galactic Nuclei

Authors: Hiromichi Tagawa, Zoltan Haiman, Imre Bartos, Bence Kocsis

Comments: 19 pages, 11 figures, submitted to ApJ

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

The astrophysical origin of gravitational wave (GW) events is one of the most timely problems in the wake of the LIGO/Virgo discoveries. In active galactic nuclei (AGN), binaries form and evolve efficiently by dynamical interactions and gaseous dissipation. Previous studies have suggested that binary black hole (BBH) mergers in AGN disks can contribute significantly to BBH mergers observed by GW interferometers. Here we examine the distribution of the effective spin parameter $\chi_\mathrm{eff}$ of this GW source population. We extend our semi-analytical model of binary formation and evolution in AGN disks by following the evolution of the binary orbital angular momenta and black hole (BH) spins. BH spins change due to gas accretion and BH mergers, while the binary orbital angular momenta evolve due to gas accretion and binary-single interactions. We find that the distribution of $\chi_\mathrm{eff}$ predicted by our AGN model is similar to the distribution observed during LIGO/Virgo O1 and O2. On the other hand, if radial migration of BHs is inefficient, $\chi_\mathrm{eff}$ is skewed toward higher values compared with the observed distribution, because of the paucity of scattering events that would randomize spin directions relative to the orbital plane. We suggest that high binary masses and the positive correlation between binary mass and the standard deviation of $\chi_\mathrm{eff}$ for chirp masses up to $\approx 20\,\mathrm{M}_\odot$, can be possible signatures for mergers originating in AGN disks. Finally, hierarchical mergers in AGN disks naturally produce properties of the recent GW event GW190412, including a low mass ratio, a high primary BH spin, and a significant spin component in the orbital plane.

[5]  arXiv:2004.11917 [pdf, other]

Title: GASP XXVII: Gas-phase metallicity scaling relations in disk galaxies with and without ram-pressure stripping

Authors: Andrea Franchetto, Benedetta Vulcani, Bianca M. Poggianti, Marco Gullieuszik, Matilde Mingozzi, Alessia Moretti, Neven Tomičić, Jacopo Fritz, Daniela Bettoni, Yara L. Jaffé

Comments: accepted for publication in ApJ, 24 pages, 21 figures, 2 tables

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

Exploiting the data from the GAs Stripping Phenomena in galaxies with MUSE (GASP) survey, we study the gas-phase metallicity scaling relations of a sample of 29 cluster galaxies undergoing ram-pressure stripping and of a reference sample of (16 cluster and 16 field) galaxies with no significant signs of gas disturbance. We adopt the PYQZ code to infer the mean gas metallicity at the effective radius and achieve a well-defined mass-metallicity relation (MZR) in the stellar mass range $10^{9.25}\le M_\star \le 10^{11.5}\,{\rm M_\odot}$ with a scatter of 0.12 dex. At any given mass, reference cluster and stripping galaxies have similar metallicities, while the field galaxies with $M_\star < 10^{10.25}\,{\rm M_\odot}$ show on average lower gas metallicity than galaxies in clusters. Our results indicate that at the effective radius the chemical properties of the stripping galaxies are independent of the ram-pressure stripping mechanism. Nonetheless, at the lowest masses we detect 4 stripping galaxies well above the common MZR that suggest a more complex scenario. Overall, we find signs of an anti-correlation between the metallicity and both the star formation rate and the galaxy size, in agreement with previous studies. No significant trends are instead found with the halo mass, clustercentric distance and local galaxy density in clusters. In conclusion, we advise a more detailed analysis of the spatially resolved gas metallicity maps of the galaxies, able to highlight effects of gas redistribution inside the disk due to the ram-pressure stripping.

[6]  arXiv:2004.11921 [pdf, other]

Title: Electron Density Structure of the Local Galactic Disk

Authors: Stella Koch Ocker, James M. Cordes, Shami Chatterjee

Comments: Submitted to ApJ

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

Pulsar dispersion measures (DMs) have been used to model the electron density of the interstellar medium (ISM) above and below the Galactic plane as a plane-parallel medium, despite significant scatter in the DM-distance distribution and strong evidence for inhomogeneities in the ISM. We use a sample of pulsars with independent distance measurements to evaluate a model of the local ISM that incorporates turbulent fluctuations, clumps, and voids in the electron density. The latter two components are required because $\sim 1/3$ of the lines of sight are discrepant from a strictly plane parallel model. A likelihood analysis for smooth components of the model yields a scale height $z_0=1.57^{+0.15}_{-0.14}$ kpc and a mid-plane density $n_0=0.015 \pm 0.001$ cm$^{-3}$. The scatter in the DM-distance distribution is dominated by clumps and voids but receives significant contributions from a broad spectrum of density fluctuations, such as a Kolmogorov spectrum. The model is used to identify lines of sight with outlier values of DM. Three of these pulsars, J1614$-$2230, J1623$-$0908, and J1643$-$1224, lie behind known HII regions, and the electron density model is combined with H$\alpha$ intensity data to constrain the filling factors and other substructure properties of the HII regions (Sh 2-7 and Sh 2-27). Several pulsars also exhibit enhanced DM fluctuations that are likely caused by their lines of sight intersecting the superbubble GSH 238+00+09.

[7]  arXiv:2004.11927 [pdf, other]

Title: Ambipolar diffusion in the Bifrost code

Authors: D. Nóbrega-Siverio, J. Martínez-Sykora, F. Moreno-Insertis, M. Carlsson

Comments: Accepted in A&A, 10 pages, 7 figures

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

Ambipolar diffusion is a physical mechanism related to the drift between charged and neutral particles in a partially ionized plasma that is key in many different astrophysical systems. However, understanding its effects is challenging due to basic uncertainties concerning relevant microphysical aspects and the strong constraints it imposes on the numerical modeling. Our aim is to introduce a numerical tool that allows us to address complex problems involving ambipolar diffusion in which, additionally, departures from ionization equilibrium are important or high resolution is needed. The primary application of this tool is for solar atmosphere calculations, but the methods and results presented here may also have a potential impact on other astrophysical systems. We have developed a new module for the stellar atmosphere Bifrost code that improves its computational capabilities of the ambipolar diffusion term in the Generalized Ohm's Law. This module includes, among other things, collision terms adequate to processes in the coolest regions in the solar chromosphere. As a key feature of the module, we have implemented the Super Time-Stepping (STS) technique, that allows an important acceleration of the calculations. We have also introduced hyperdiffusion terms to guarantee the stability of the code. We show that to have an accurate value for the ambipolar diffusion coefficient in the solar atmosphere it is necessary to include as atomic elements in the equation of state not only hydrogen and helium but also the main electron donors like sodium, silicon and potassium. In addition, we establish a range of criteria to set up an automatic selection of the free parameters of the STS method that guarantees the best performance, optimizing the stability and speed for the ambipolar diffusion calculations. We validate the STS implementation by comparison with a self-similar analytical solution.

[8]  arXiv:2004.11929 [pdf, ps, other]

Title: Robust posterior inference when statistically emulating forward simulations

Authors: Grigor Aslanyan, Richard Easther, Nathan Musoke, Layne C. Price

Comments: code available from this https URL or this https URL

Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Cosmology and Nongalactic Astrophysics (astro-ph.CO); Machine Learning (cs.LG); Machine Learning (stat.ML)

Scientific analyses often rely on slow, but accurate forward models for observable data conditioned on known model parameters. While various emulation schemes exist to approximate these slow calculations, these approaches are only safe if the approximations are well understood and controlled. This workshop submission reviews and updates a previously published method, which has been used in cosmological simulations, to (1) train an emulator while simultaneously estimating posterior probabilities with MCMC and (2) explicitly propagate the emulation error into errors on the posterior probabilities for model parameters. We demonstrate how these techniques can be applied to quickly estimate posterior distributions for parameters of the $\Lambda$CDM cosmology model, while also gauging the robustness of the emulator approximation.

[9]  arXiv:2004.11936 [pdf, other]

Title: Orbital Migration of Interacting Stellar Mass Black Holes in Disks around Supermassive Black Holes II. Spins and Incoming Objects

Authors: Amy Secunda, Jillian Bellovary, Mordecai-Mark Mac Low, K. E. Saavik Ford, Barry McKernan, Nathan W. C. Leigh, Wladimir Lyra, Zsolt Sandor, Jose I. Adorno

Comments: 16 pages, 9 figures, updated from version submitted to ApJ to include reference to GW190412

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

The mass, rate, and spins of merging stellar-mass binary black holes (BBHs) detected by aLIGO and Advanced Virgo provide challenges to traditional BBH formation and merger scenarios. An active galactic nucleus (AGN) disk provides a promising additional merger channel, because of the powerful influence of the gas that drives orbital evolution, makes encounters dissipative, and leads to migration. Previous work showed that stellar mass black holes (sBHs) in an AGN disk migrate to regions of the disk, known as migration traps, where positive and negative gas torques cancel out, leading to frequent BBH formation. Here we build on that work by simulating the evolution of additional sBHs that enter the inner disk by either migration or inclination reduction. We also examine whether the BBHs formed in our models have retrograde or prograde orbits around their centers of mass with respect to the disk, determining the orientation, relative to the disk, of the spin of the merged BBHs. We find that orbiters entering the inner disk form BBHs, that are commonly asymmetric in mass, with sBHs on resonant orbits near the migration trap. When these black holes reach 80 solar masses, they form BBHs with sBHs in the migration trap, which over 10 Myr reach about 1000 solar masses. We also find that 68% of the BBHs in our simulation orbit in the retrograde direction, which implies our merger channel could easily produce the low values of the dimensionless aligned spin, chi_eff, observed in a majority of BBH mergers detected thus far.

[10]  arXiv:2004.11981 [pdf, other]

Title: DeepMerge: Classifying High-redshift Merging Galaxies with Deep Neural Networks

Authors: A. Ćiprijanović, G. F. Snyder, B. Nord, J. E. G. Peek

Comments: 17 pages, 8 figures, submitted to Astronomy & Computing

Subjects: Astrophysics of Galaxies (astro-ph.GA); Instrumentation and Methods for Astrophysics (astro-ph.IM); Computer Vision and Pattern Recognition (cs.CV)

We investigate and demonstrate the use of convolutional neural networks (CNNs) for the task of distinguishing between merging and non-merging galaxies in simulated images, and for the first time at high redshifts (i.e. $z=2$). We extract images of merging and non-merging galaxies from the Illustris-1 cosmological simulation and apply observational and experimental noise that mimics that from the Hubble Space Telescope; the data without noise form a "pristine" data set and that with noise form a "noisy" data set. The test set classification accuracy of the CNN is $79\%$ for pristine and $76\%$ for noisy. The CNN outperforms a Random Forest classifier, which was shown to be superior to conventional one- or two-dimensional statistical methods (Concentration, Asymmetry, the Gini, $M_{20}$ statistics etc.), which are commonly used when classifying merging galaxies. We also investigate the selection effects of the classifier with respect to merger state and star formation rate, finding no bias. Finally, we extract Grad-CAMs (Gradient-weighted Class Activation Mapping) from the results to further assess and interrogate the fidelity of the classification model.

[11]  arXiv:2004.12033 [pdf, other]

Title: Ram pressure stripping candidates in the Coma Cluster: Evidence for enhanced star formation

Authors: Ian D. Roberts, Laura C. Parker

Comments: 12 pages, 7 figures, plus appendix. Accepted to MNRAS

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

The Coma cluster is the nearest massive ($M \gtrsim 10^{15}\,\mathrm{M_\odot}$) galaxy cluster, making it an excellent laboratory to probe the influence of the cluster environment on galaxy star formation. Here, we present a sample of 41 galaxies with disturbed morphologies consistent with ram pressure stripping. These galaxies are identified visually using high-quality, multi-band imaging from the Canada-France-Hawaii telescope covering ~9 $\mathrm{deg^2}$ of the Coma cluster. These "stripping candidates" are clear outliers in common quantitative morphological measures, such as concentration-asymmetry and Gini-$M_{20}$, confirming their disturbed nature. Based on the orientations of observed asymmetries, as well as the galaxy positions in projected phase-space, these candidates are consistent with galaxies being stripped shortly after infall onto the Coma cluster. Finally, the stripping candidates show enhanced star formation rates, both relative to "normal" star-forming Coma galaxies and isolated galaxies in the field. Ram pressure is likely driving an enhancement in star formation during the stripping phase, prior to quenching. On the whole, ram pressure stripping appears to be ubiquitous across all regions of the Coma cluster.

[12]  arXiv:2004.12050 [pdf, ps, other]

Title: Is GRB 110715A the progenitor of FRB 171209?

Authors: Xiang-Gao Wang (GXU), Long Li (GXU), Yuan-Pei Yang (YNU), Jia-Wei Luo (UNLV), Bing Zhang (UNLV), Da-Bin Lin (GXU), En-Wei Liang (GXU), Song-Mei Qin (GXUCM)

Comments: Accepted for publication in ApJL; 8 pages, 5 figures

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

The physical origin of fast radio bursts (FRBs) is unknown. Young magnetars born from gamma-ray bursts (GRBs) have been suggested to be a possible central engine of FRBs. We test such a hypothesis by systematically searching for GRB-FRB spatial associations from 110 FRBs and 1440 GRBs. We find that one FRB event, FRB 171209, discovered by the Parkes telescope is spatially coincident with a historical long-duration GRB 110715A at $z=0.82$. The afterglow of GRB 110715A is consistent with being powered by a millisecond magnetar. The extragalactic dispersion measure of FRB 171209 is in excess of that contributed by the intergalactic medium, which can be interpreted as being contributed by a young supernova remnant associated with the GRB. Overall, the significance of the association is $(2.28 - 2.55) \sigma$. If the association is indeed physical, our result suggests that the magnetars associated with long GRBs can be the progenitors of at least some FRBs.

[13]  arXiv:2004.12096 [pdf, other]

Title: Multiband Observation of LIGO/Virgo Binary Black Hole Mergers in the Gravitational-wave Transient Catalog GWTC-1

Authors: Chang Liu, Lijing Shao, Junjie Zhao, Yong Gao

Comments: 16 pages, 5 figures, 6 tables

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

The Advanced LIGO and Virgo detectors opened a new era to study black holes (BHs) in our Universe. A population of stellar-mass binary BHs (BBHs) are discovered to be heavier than previously expected. These heavy BBHs provide us an opportunity to achieve multiband observation with ground-based and space-based gravitational-wave (GW) detectors. In this work, we use BBHs discovered by the LIGO/Virgo Collaboration as indubitable examples, and study in great detail the prospects for multiband observation with GW detectors in the near future. We apply the Fisher matrix to spinning, non-precessing inspiral-merger-ringdown waveforms, while taking the motion of space-based GW detectors fully into account. Our analysis shows that, detectors with decihertz sensitivity are expected to log stellar-mass BBH signals with very large signal-to-noise ratio, and provide accurate parameter estimation, including the sky location and time to coalescence. Furthermore, the combination of multiple detectors will achieve unprecedented measurement of BBH properties. As an explicit example, we present the multiband sensitivity to the generic dipole radiation for BHs, which is vastly important for the equivalence principle in the foundation of gravitation, in particular for those theories that predict curvature-induced scalarization of BHs.

[14]  arXiv:2004.12105 [pdf, other]

Title: Observing the Earliest Stages of Star Formation in Galaxies: 8 micron Cores in Three Edge-on Disks

Authors: Bruce G. Elmegreen, Debra M. Elmegreen

Comments: 15 pages, 15 figures, 7 tables, in press for ApJ

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

To study the vertical distribution of the earliest stages of star formation in galaxies, three edge-on spirals, NGC 891, NGC 3628, and IC 5052 observed by the Spitzer Space Telescope InfraRed Array Camera (IRAC) were examined for compact 8 micron cores using an unsharp mask technique; 173, 267, and 60 cores were distinguished, respectively. Color-color distributions suggest a mixture of PAHs and highly-extincted photospheric emission from young stars. The average V-band extinction is ~20 mag, equally divided between foreground and core. IRAC magnitudes for the clumps are converted to stellar masses assuming an age of 1 Myr, which is about equal to the ratio of the total core mass to the star formation rate in each galaxy. The extinction and stellar mass suggest an intrinsic core diameter of ~18 pc for 5% star formation efficiency. The half-thickness of the disk of 8 micron cores is 105 pc for NGC 891 and 74 pc for IC 5052, varying with radius by a factor of ~2. For NGC 3628, which is interacting, the half-thickness is 438 pc, but even with this interaction, the 8 micron disk is remarkably flat, suggesting vertical stability. Small scale structures like shingles or spirals are seen in the core positions. Very few of the 8 micron cores have optical counterparts.

[15]  arXiv:2004.12128 [pdf, ps, other]

Title: Astronomical Site Monitoring System at Lijiang Observatory

Authors: Yu-Xin Xin, Jin-Ming Bai, Bao-Li Lun, Yu-Feng Fan, Chuan-Jun Wang, Xiao-Wei Liu, Xiao-Guang Yu, Kai Ye, Teng-Fei Song, Liang Chang, Shou-Sheng He, Ji-Rong Mao, Liang Xu, Ding-Rong Xiong, Xi-Liang Zhang, Jian-Guo Wang, Xu Ding, Hai-Cheng Feng, Xiang-Kun Liu, Yang Huang, Bing-Qiu Chen

Comments: 21 pages,40 figures

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

We installed two sets of Astronomical Site Monitoring System(ASMS) at Lijiang Observatory(GMG), for the running of the 2.4-meter Lijiang optical telescope(LJT) and the 1.6-meter Multi-channel Photometric Survey Telescope (Mephisto). The Mephistro is under construction. ASMS has been running on robotic mode since 2017. The core instruments: Cloud Sensor, All-Sky Camera and Autonomous-DIMM that are developed by our group, together with the commercial Meteorological Station and Sky Quality Meter, are combined into the astronomical optical site monitoring system. The new Cloud Sensor's Cloud-Clear Relationship is presented for the first time, which is used to calculate the All-Sky cloud cover. We designed the Autonomous-DIMM located on a tower, with the same height as LJT. The seeing data have been observed for a full year. ASMS's data for the year 2019 are also analysed in detail, which are valuable to observers.

[16]  arXiv:2004.12132 [pdf]

Title: Hubble Telescope 30 Years in Orbit: Personal Reflections

Authors: Robert Williams

Comments: 8 pages, 3 figures

Journal-ref: Res Ast & Ap, 20, 44 (2020)

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

With an initial requirement to make observations a minimum of 5-10 years, Hubble Space Telescope (HST) has continued to operate well for 30 years. It has relied upon five servicing missions to repair and replace essential components. Since the final Space Shuttle mission 10 years ago it has avoided major breaks in its operation, with the only serious effects of ageing in space being a progressive deterioration in the performance of the gyroscopes and sensitivity of the instrument detectors. A number of factors were important in making HST a scientific landmark. Ground-breaking discoveries have been made with HST----the most important being the discovery of cosmic acceleration. When HST operation ceases future observations in space should be assured with successful operation of major missions now planned by NASA, ESA, and the China and Japanese Space Agencies.

[17]  arXiv:2004.12136 [pdf, other]

Title: SpecPhot: A Comparison of Spectroscopic and Photometric Exoplanet Follow-Up Methods

Authors: Benjamin F. Cooke (1 and 2), Don Pollacco (1 and 2) ((1) Department of Physics University of Warwick UK, (2) Centre for Exoplanets and Habitability University of Warwick UK)

Comments: 10 pages, 7 figures. Accepted for publication in MNRAS

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

We set out a simulation to explore the follow-up of exoplanet candidates. We look at comparing photometric (transit method) and spectroscopic (Doppler shift method) techniques using three instruments: NGTS, HARPS and CORALIE. We take into account precision of follow-up and required observing time in attempt to rank each method for a given set of planetary system parameters. The methods are assessed on two criteria, SNR of the detection and follow-up time before characterisation. We find that different follow-up techniques are preferred for different regions of parameter space. For SNR we find that the ratio of spectroscopic to photometric SNR for a given system goes like $R_p/P^{\frac{1}{3}}$. For follow-up time we find that photometry is favoured for the shortest period systems ($<10$ d) as well as systems with small planet radii. Spectroscopy is then preferred for systems with larger radius, and thus more massive, planets (given our assumed mass-radius relationship). Finally, we attempt to account for availability of telescopes and weight the two methods accordingly.

[18]  arXiv:2004.12176 [pdf, other]

Title: Measuring turbulent motion in planet-forming disks with ALMA: A detection around DM Tau and non-detections around MWC 480 and V4046 Sgr

Authors: Kevin Flaherty, A. Meredith Hughes, Jacob B. Simon, China Qi, Xue-ning Bai, Alyssa Bulatek, Sean M. Andrews, David J. Wilner, Agnes Kospal

Comments: 21 pages, 10 figures, accepted to ApJ

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

Turbulence is a crucial factor in many models of planet formation, but it has only been directly constrained among a small number of planet forming disks. Building on the upper limits on turbulence placed in disks around HD 163296 and TW Hya, we present ALMA CO J=2-1 line observations at $\sim0.3"$ (20-50 au) resolution and 80 ms$^{-1}$ channel spacing of the disks around DM Tau, MWC 480, and V4046 Sgr. Using parametric models of disk structure, we robustly detect non-thermal gas motions around DM Tau of between 0.25 c$_s$ and 0.33 c$_s$, with the range dominated by systematic effects, making this one of the only systems with directly measured non-zero turbulence. Using the same methodology, we place stringent upper limits on the non-thermal gas motion around MWC 480 ($<$0.08c$_s$) and V4046 Sgr ($<$0.12 c$_s$). The preponderance of upper limits in this small sample, and the modest turbulence levels consistent with dust studies, suggest that weak turbulence ($\alpha\lesssim10^{-3}$) may be a common, albeit not universal, feature of planet-forming disks. We explore the particular physical conditions around DM Tau that could lead this system to be more turbulent than the others.

[19]  arXiv:2004.12215 [pdf, other]

Title: High latitude emission from structured jet of Gamma-Ray Bursts observed off-axis

Authors: Stefano Ascenzi, Gor Oganesyan, Om S. Salafia, Marica Branchesi, Giancarlo Ghirlanda, Simone Dall'Osso

Comments: 15 pages, 11 figures. Submitted to Astronomy & Astrophysics

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

The X-ray emission of gamma-ray bursts (GRBs) is often characterized by an initial steep decay, followed by a nearly constant emission phase (so called "plateau") which can extend up to thousands of seconds. While the steep decay is usually interpreted as the tail of the prompt gamma-ray flash, the long-lasting plateau is commonly associated to the emission from the external shock sustained by energy injection from a long lasting central engine. A recent study proposed an alternative interpretation, ascribing both the steep decay and the plateau to high-latitude emission (HLE) from a "structured jet" whose energy and bulk Lorentz factor depend on the angular distance from the jet symmetry axis. In this work we expand over this idea and explore more realistic conditions: (a) the finite duration of the prompt emission, (b) the angular dependence of the optical depth and (c) the lightcurve dependence on the observer viewing angle. We find that, when viewed highly off-axis, the structured jet HLE lightcurve is smoothly decaying with no clear distinction between the steep and flat phase, as opposed to the on-axis case. For a realistic choice of physical parameters, the effects of a latitude-dependent Thomson opacity and finite duration of the emission have a marginal effect on the overall lightcurve evolution. We discuss the possible HLE of GW170817, showing that the emission would have faded away long before the first Swift-XRT observations. Finally, we discuss the prospects for the detection of HLE from off-axis GRBs by present and future wide-field X-ray telescopes and X-ray surveys, such as eROSITA and the mission concept THESEUS.

[20]  arXiv:2004.12218 [pdf, other]

Title: First Hubble diagram and cosmological constraints using superluminous supernova

Authors: C. Inserra, M. Sullivan, C. R. Angus, E. Macaulay, R. C. Nichol, M. Smith, C. Frohmaier, C. P. Gutiérrez, A. Möller, D. Brout, P. J. Brown, T. M. Davis, C. B. D'Andrea, L. Galbany, R. Kessler, A. G. Kim, Y.-C. Pan, M. Pursiainen, D. Scolnic, B. P. Thomas, P. Wiseman, T. M. C. Abbott, J. Annis, S. Avila, E. Bertin, D. Brooks, D. L. Burke, A. Carnero Rosell, M. Carrasco Kind, J. Carretero, F. J. Castander, R. Cawthon, J. De Vicente, S. Desai, H. T. Diehl, T. F. Eifler, D. A. Finley, B. Flaugher, P. Fosalba, J. Frieman, J. Garcia-Bellido, E. Gaztanaga, D. W. Gerdes, T. Giannantonio, D. Gruen, R. A. Gruendl, J. Gschwend, G. Gutierrez, D. L. Hollowood, K. Honscheid, D. J. James, E. Krause, K. Kuehn, N. Kuropatkin, T. S. Li, C. Lidman, M. Lima, M. A. G. Maia, J. L. Marshall, P. Martini, et al. (31 additional authors not shown)

Comments: 14 oages, 7 figures. Comments are welcome

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

We present the first Hubble diagram of superluminous supernovae (SLSNe) out to a redshift of two, together with constraints on the matter density, $\Omega_{\rm M}$, and the dark energy equation-of-state parameter, $w(\equiv p/\rho)$. We build a sample of 20 cosmologically useful SLSNe~I based on light curve and spectroscopy quality cuts. We confirm the robustness of the peak decline SLSN~I standardization relation with a larger dataset and improved fitting techniques than previous works. We then solve the SLSN model based on the above standardisation via minimisation of the $\chi^2$ computed from a covariance matrix which includes statistical and systematic uncertainties. For a spatially flat $\Lambda$CDM cosmological model, we find $\Omega_{\rm M}=0.44^{+0.21}_{-0.21}$, with a rms of 0.28 mag for the residuals of the distance moduli. For an $w_0w_a$CDM cosmological model, the addition of SLSNe~I to a `baseline' measurement consisting of Planck temperature and WMAP polarization of the cosmic microwave background (CMB) fluctuation together with type Ia supernovae, results in a small improvement in the constraints of $w_0$ and $w_a$ of 4\%. We present simulations of future surveys with 847 SLSNe I and show that such a sample can deliver cosmological constraints in a flat $\Lambda$CDM model with the same precision (considering only statistical uncertainties) as current surveys that use type Ia supernovae, while providing an improvement of 15\% in the constraints on the time variation of dark energy, $w_0$ and $w_a$. This paper represents the proof-of-concept for superluminous supernova cosmology, and demonstrates they can provide an independent test of cosmology in the high-redshift ($z>1$) universe.

[21]  arXiv:2004.12229 [pdf]

Title: Virtues of Including Hydrogen in the Patterns of Element Abundances in Solar Energetic Particles

Authors: Donald V. Reames

Comments: 13 pages, 2 figures, submitted to Solar Phys

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

We revisit a multi-spacecraft study of the element abundances of solar energetic particles (SEPs) in the 23 January 2012 event, where the power-law pattern of enhancements versus the mass-to-charge ratio A/Q for the elements C through Fe was partly disrupted by a break near Mg, which turned out to be an unfortunate distraction. In the current article we find that extending that least-squares fits for C - Fe down to H at A/Q = 1 lends much more credence to the power laws, even though H itself was not included in the fits. We also investigate the extent of an adiabatically invariant "reservoir" of magnetically-trapped particles behind the shock wave in this event.

[22]  arXiv:2004.12267 [pdf, ps, other]

Title: Early Optical Observations of GRB 150910A: Bright Jet Optical Afterglow and X-ray Dipole Radiation from a Magnetar Central Engine

Authors: Lang Xie (GXU), Xiang-Gao Wang (GXU), Song-Mei Qin (GXUCM), WeiKang Zheng (UCB), Alexei V. Filippenko (UCB), Long Li (GXU), Tian-Ci Zheng (GXU) Le Zou (GXU), Da-Bin Lin (GXU), Yinan Zhu (SYU), Heechan Yuk (UO), Rui-Jing Lu (GXU), En-Wei Liang (GXU)

Comments: Accepted for publication in ApJ; 26 pages, 8 figures, 3 tables

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

Gamma-ray burst (GRB) 150910A was detected by {\it Swift}/BAT, and then rapidly observed by {\it Swift}/XRT, {\it Swift}/UVOT, and ground-based telescopes. We report Lick Observatory spectroscopic and photometric observations of GRB~150910A, and we investigate the physical origins of both the optical and X-ray afterglows, incorporating data obtained with BAT and XRT. The light curves show that the jet emission episode lasts $\sim 360$~s with a sharp pulse from BAT to XRT (Episode I). In Episode II, the optical emission has a smooth onset bump followed by a normal decay ($\alpha_{\rm R,2} \approx -1.36$), as predicted in the standard external shock model, while the X-ray emission exhibits a plateau ($\alpha_{\rm X,1} \approx -0.36$) followed by a steep decay ($\alpha_{\rm X,2} \approx -2.12$). The light curves show obvious chromatic behavior with an excess in the X-ray flux. Our results suggest that GRB 150910A is an unusual GRB driven by a newly-born magnetar with its extremely energetic magnetic dipole (MD) wind in Episode II, which overwhelmingly dominates the observed early X-ray plateau. The radiative efficiency of the jet prompt emission is $\eta_{\gamma} \approx 11\%$. The MD wind emission was detected in both the BAT and XRT bands, making it the brightest among the current sample of MD winds seen by XRT. We infer the initial spin period ($P_0$) and the surface polar cap magnetic field strength ($B_p$) of the magnetar as $1.02 \times 10^{15}~{\rm G} \leq B_{p} \leq 1.80 \times 10^{15}~{\rm G}$ and 1~ms $\leq P_{0}v\leq 1.77$~ms, and the radiative efficiency of the wind is $\eta_w \geq 32\%$.

[23]  arXiv:2004.12372 [pdf, ps, other]

Title: AstroSat observation of the Be/X-ray binary Pulsar 3A 0726-260 (4U 0728-25)

Authors: Jayashree Roy, P. C. Agrawal, B. Singari, R. Misra

Comments: Accepted for publication in Research in Astronomy and Astrophysics (RAA) Journal

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

Results on timing and spectral properties of the Be/X-ray binary pulsar 3A 0726-260 (4U 0728-25) are presented. The binary was observed on 2016 May 6-7 with the Large Area X-ray Proportional Counter (LAXPC) and Soft X-ray Telescope (SXT) instruments onboard the AstroSat satellite. During this observation the source was in non-flaring persistent state at a flux level of $\sim$ 8.6 $\pm$ 0.3 $\times$10$^{-11}$ ergs cm$^{-2}$ sec$^{-1}$ in 0.4-20 keV. Strong X-ray pulsations with a period of 103.144$\pm$0.001 seconds are detected in 0.3-7 keV with the SXT and in 3-40 keV with the LAXPC. The pulse profile is energy dependent, and there is an indication that the pulse shape changes from a broad single pulse to a double pulse at higher energy. At energies above 20 keV, we report the first time detection of pulsation period 103.145$\pm$0.001 seconds and the double peaked pulse profile from the source. The energy spectrum of the source is derived from the combined analysis of the SXT and LAXPC spectral data in 0.4-20 keV. The best spectral fit is obtained by a power law model with a photon index (1.7$\pm$0.03) with high energy spectral cut-off at 12.9 $\pm$ 0.7 keV. A broad Iron line at $\sim$ 6.3 keV is detected in the energy spectrum. We briefly discuss the implications of these results.

[24]  arXiv:2004.12396 [pdf, other]

Title: Infrared interferometry to spatially and spectrally resolve jets in X-ray binaries

Authors: Sera Markoff, David M. Russell, Jason Dexter, Oliver Pfuhl, Frank Eisenhauer, Roberto Abuter, James C.A. Miller-Jones, Thomas D. Russell

Comments: 12 Pages, 3 figures, accepted for publication in MNRAS

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

Infrared interferometry is a new frontier for precision ground based observing, with new instrumentation achieving milliarcsecond (mas) spatial resolutions for faint sources, along with astrometry on the order of 10 microarcseconds. This technique has already led to breakthroughs in the observations of the supermassive black hole at the Galactic centre and its orbiting stars, AGN, and exo-planets, and can be employed for studying X-ray binaries (XRBs), microquasars in particular. Beyond constraining the orbital parameters of the system using the centroid wobble and spatially resolving jet discrete ejections on mas scales, we also propose a novel method to discern between the various components contributing to the infrared bands: accretion disk, jets and companion star. We demonstrate that the GRAVITY instrument on the Very Large Telescope Interferometer (VLTI) should be able to detect a centroid shift in a number of sources, opening a new avenue of exploration for the myriad of transients expected to be discovered in the coming decade of radio all-sky surveys. We also present the first proof-of-concept GRAVITY observation of a low-mass X-ray binary transient, MAXI J1820+070, to search for extended jets on mas scales. We place the tightest constraints yet via direct imaging on the size of the infrared emitting region of the compact jet in a hard state XRB.

[25]  arXiv:2004.12419 [pdf, other]

Title: Birth of convective low-mass to high-mass second Larson cores

Authors: Asmita Bhandare, Rolf Kuiper, Thomas Henning, Christian Fendt, Mario Flock, Gabriel-Dominique Marleau

Comments: 22 pages, 20 figures, and 2 tables. Accepted for publication in A&A. Collapse movie: this https URL

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

Stars form as an end product of the gravitational collapse of cold, dense gas in magnetized molecular clouds. This multi-scale scenario occurs via the formation of two quasi-hydrostatic cores and involves complex physical processes, which require a robust, self-consistent numerical treatment. The aim of this study is to understand the formation and evolution of the second Larson core and the dependence of its properties on the initial cloud core mass. We used the PLUTO code to perform high resolution, 1D and 2D RHD collapse simulations. We include self-gravity and use a grey FLD approximation for the radiative transfer. Additionally, we use for the gas EOS density- and temperature-dependent thermodynamic quantities to account for the effects such as dissociation, ionisation, and molecular vibrations and rotations. Properties of the second core are investigated using 1D studies spanning a wide range of initial cloud core masses from 0.5 to 100 $M_{\odot}$. Furthermore, we expand to 2D collapse simulations for a few cases of 1, 5, 10, and 20 $M_{\odot}$. We follow the evolution of the second core for $\geq$ 100 years after its formation, for each of these non-rotating cases. Our results indicate a dependence of several second core properties on the initial cloud core mass. For the first time, due to an unprecedented resolution, our 2D non-rotating collapse studies indicate that convection is generated in the outer layers of the second core, which is formed due to the gravitational collapse of a 1 $M_{\odot}$ cloud core. Additionally, we find large-scale oscillations of the second accretion shock front triggered by the standing accretion shock instability, which has not been seen before in early evolutionary stages of stars. We predict that the physics within the second core would not be significantly influenced by the effects of magnetic fields or an initial cloud rotation.

[26]  arXiv:2004.12421 [pdf, other]

Title: Post-Newtonian waveform for charged binary black hole inspirals and analysis with GWTC-1 events

Authors: Hai-Tian Wang, Peng-Cheng Li, Jin-Liang Jiang, Yi-Ming Hu, Yi-Zhong Fan

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

Since the first detection in 2015, ten black hole binary merger events have been formally reported. These gravitational wave signals have significantly enhanced our understanding of the black hole astrophysics. In general, the properties of a black hole are comprehensively described by its mass, spin, and charge. The third parameter is often ignored because of the very low value expected in the realistic astrophysical environment. In this work, we constrain the amount of charge in a way which is equivalent to the parametrized post-Einsteinian framework by treating the charge as a small perturbation with Bayesian method, and we find that the current limit on the charge is similar to the one obtained by the Fisher information matrix method in previous works. Then we develop a zeroth order post-Newtonian waveform for charged binary black hole inspirals, and apply this charged waveform to the binary black hole merger events observed by LIGO-Virgo in their first two runs. A Bayesian model selection is performed among the post-Newtonian waveform, charged post-Newtonian waveform, and full inspiral-merger-ringdown waveform. Remarkably, we show that charged post-Newtonian waveform matches the LIGO-Virgo data better compared with non-charged post-Newtonian waveform, mainly due to the influence in the late inspiral period, and the full inspiral-merger-ringdown outrun both by far. The inclusion of charge in the waveform might shift the estimated parameters significantly. Finally, we obtain certain constraints on the binary black hole charges and discuss the drawbacks. Our work calls for the development of a full inspiral-merger-ringdown waveform for charged binary black hole merger, so that more meaningful constraints could be obtained.

[27]  arXiv:2004.12434 [pdf, ps, other]

Title: Development in astronomy in Ethiopia and East-Africa through nuclear activity in galaxies

Authors: Mirjana Pović

Comments: 5 pages; Proceedings paper of the IAU symposium 356 "Nuclear Activity in Galaxies Across Cosmic Time" (Ethiopia) accepted to be published under the Cambridge University Press, eds. M. Povi\'c, P. Marziani, J. Masegosa, H. Netzer, S. H. Negu, and S. B. Tessema

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

In this paper we summarise the research that is currently going on in Ethiopia and East-Africa in extragalactic astronomy and physics of active galaxies and active galactic nuclei (AGN). The study is focused on some of the still open questions such as: what are the stellar ages and populations of ultra hard X-ray detected AGN and connection between AGN and their host galaxies?, what are the properties of AGN in galaxy clusters and the role that environment has in triggering nuclear activity?, what are the morphological properties of AGN and how precisely we can deal with morphological classification of active galaxies?, what are the properties of galaxies in the green valley and the role of AGN in galaxy evolution?, and what are the properties of radio-loud and radio-quiet quasars (QSO) and dichotomy between the two?. Each of these questions has been developed under one specific project that will be briefly introduced. These projects involve 6 PhD and 3 MSc students and collaborations between Ethiopia, Rwanda, South Africa, Uganda, Tanzania, Spain, Italy, and Chile. With all projects we aim: first, to contribute to our general knowledge about AGN, and second, to contribute to the development in astronomy and science in Ethiopia and East-Africa.

[28]  arXiv:2004.12439 [pdf, ps, other]

Title: Resolving the soft X-ray ultra fast outflow in PDS 456

Authors: James Reeves, Valentina Braito, George Chartas, Fred Hamann, Sibasish Laha, Emanuele Nardini

Comments: 13 pages, accepted for publication in the Astrophysical Journal

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

Past X-ray observations of the nearby luminous quasar PDS 456 (at $z=0.184$) have revealed a wide angle accretion disk wind (Nardini et al. 2015), with an outflow velocity of $\sim-0.25c$, as observed through observations of its blue-shifted iron K-shell absorption line profile. Here we present three new XMM-Newton observations of PDS 456; one in September 2018 where the quasar was bright and featureless, and two in September 2019, 22 days apart, occurring when the quasar was five times fainter and where strong blue-shifted lines from the wind were present. During the second September 2019 observation, three broad ($\sigma=3000$ km s$^{-1}$) absorption lines were resolved in the high resolution RGS spectrum, which are identified with blue-shifted OVIII Ly$\alpha$, NeIX He$\alpha$ and NeX Ly$\alpha$. The outflow velocity of this soft X-ray absorber was found to be $v/c=-0.258\pm0.003$, fully consistent with iron K absorber with $v/c=-0.261\pm0.007$. The ionization parameter and column density of the soft X-ray component ($\log\xi=3.4$, $N_{\rm H}=2\times10^{21}$ cm$^{-2}$) outflow was lower by about two orders of magnitude, when compared to the high ionization wind at iron K ($\log\xi=5$, $N_{\rm H}=7\times10^{23}$ cm$^{-2}$). Substantial variability was seen in the soft X-ray absorber between the 2019 observations, declining from $N_{\rm H}=10^{23}$ cm$^{-2}$ to $N_{\rm H}=10^{21}$ cm$^{-2}$ over 20 days, while the iron K component was remarkably stable. We conclude that the soft X-ray wind may originate from an inhomogeneous wind streamline passing across the line of sight and which due to its lower ionization, is located further from the black hole, on parsec scales, than the innermost disk wind.

[29]  arXiv:2004.12460 [pdf, other]

Title: Multi-Messenger Searches in Astrophysics

Authors: Kathrin Egberts

Comments: 10 pages, 3 figures

Journal-ref: PoS LeptonPhoton2019 (2019) 030

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

Multi-messenger astronomy has experienced an explosive development in the past few years. While not being a particularly young field, it has recently attracted a lot of attention by several major discoveries and unprecedented observation campaigns covering the entity of the electromagnetic spectrum as well as observations of cosmic rays, neutrinos, and gravitational waves. The exploration of synergies is in full steam and requires close cooperation between different instruments. Here I give an overview over the subject of multi-messenger astronomy and its virtues compared to classical "single messenger" observations, present the recent break throughs of the field, and discuss some of its organisational and technical challenges.

[30]  arXiv:2004.12475 [pdf, ps, other]

Title: Properties of Sub-Neptune Atmospheres: TOI-270 System

Authors: J. Chouqar, Z. Benkhaldoun, A. Jabiri, J. Lustig-Yaeger, A. Soubkiou, A. Szentgyorgyi

Comments: accepted for publication on MNRAS

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

We investigate the potential for the James Webb Space Telescope (JWST) to detect and characterize the atmospheres of the sub-Neptunian exoplanets in the TOI-270 system. Sub-Neptunes are considered more likely to be water worlds than gas dwarfs. We model their atmospheres using three atmospheric compositions - two examples of hydrogen-dominated atmospheres and a water-dominated atmosphere. We then simulate the infrared transmission spectra of these atmospheres for JWST instrument modes optimized for transit observation of exoplanet atmospheres : NIRISS, NIRSpec and MIRI. We then predict the observability of each exoplanet's atmosphere. TOI-270c and d are excellent targets for detecting atmospheres with JWST transmission spectroscopy, requiring only 1 transit observation with NIRISS, NIRSpec and MIRI; higher signal-to-noise (SNR) can be obtained for a clear H-rich atmosphere. Fewer than 3 transits with NIRISS and NIRSpec may be enough to reveal molecular features. Water-dominated atmospheres require more transits. Water spectral features in water-dominated atmospheres may be detectable with NIRISS in 2 or 3 transits. We find that the detection of spectral features in a cloudy, H-rich atmosphere does not require integrations as long as those required for the water-dominated atmosphere, which is consistent with the differences in atmospheric mean molecular weight. TOI-270c and d could be prime targets for JWST transit observations of sub-Neptune atmospheres. These results provide useful predictions for observers who may propose to use JWST to detect and characterize the TOI-270 planet atmospheres.

[31]  arXiv:2004.12499 [pdf, other]

Title: Considerations for a new low-/moderate-resolution optical facility spectrograph at the VLT Coudé focus

Authors: Valentin D. Ivanov, Jean-Louis Lizon

Comments: 14 pages, 1 figure; write up of a poster presented at The Very Large Telescope in 2030 workshop, ESO Garching, June 17-20, 2019

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

Observing at the VLT Coude focus can boost the collecting area by combining light from multiple VLT unit telescopes (UTs; albeit with some losses in the light train). An instrument at the Coude enjoys significant operational flexibility advantage: it can be attached to any available UT and the "extra" instrument can help to match better the observing constraints with the current conditions. With modifications to the existing train it can even observe in parallel with ESPRESSO with different UTs. Here we consider a general purpose VLT Coude fiber-fed low-resolution facility spectrograph - provisionally named Cappuccino - suitable for rapid follow up and characterization of faint transients, for late-stage monitoring of transients and for rapid classification under poor conditions or during twilight. Like any instrument of its class, Cappuccino can be used to address diverse set of science questions. The building cost can be reduced greatly if it is based - with modest changes - on existing hardware.

[32]  arXiv:2004.12509 [pdf, other]

Title: Pluto's Ultraviolet Spectrum, Surface Reflectance, and Airglow Emissions

Authors: Andrew J. Steffl, Leslie A. Young, Darrell F. Strobel, Joshua A. Kammer, J. Scott Evans, Michael H. Stevens, Rebecca N. Schindhelm, Joel Wm. Parker, S. Alan Stern, Harold A. Weaver, Catherine B. Olkin, Kimberly Ennico, Jay R. Cummings, G. Randall Gladstone, Thomas K. Greathouse, David P. Hinson, Kurt D. Retherford, Michael E. Summers, Maarten Versteeg

Comments: 27 pages, 8 figures

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

During the New Horizons spacecraft's encounter with Pluto, the Alice ultraviolet spectrograph conducted a series of observations that detected emissions from both the interplanetary medium (IPM) and Pluto. In the direction of Pluto, the IPM was found to be 133.4$\pm$0.6R at Lyman $\alpha$, 0.24$\pm$0.02R at Lyman $\beta$, and <0.10R at He I 584{\AA}. We analyzed 3,900s of data obtained shortly before closest approach to Pluto and detect airglow emissions from H I, N I, N II, N$_2$, and CO above the disk of Pluto. We find Pluto's brightness at Lyman $\alpha$ to be $29.3\pm1.9$R, in good agreement with pre-encounter estimates. The detection of the N II multiplet at 1085{\AA} marks the first direct detection of ions in Pluto's atmosphere. We do not detect any emissions from noble gasses and place a 3$\sigma$ upper limit of 0.14 R on the brightness of the Ar I 1048{\AA} line. We compare pre-encounter model predictions and predictions from our own airglow model, based on atmospheric profiles derived from the solar occultation observed by New Horizons, to the observed brightness of Pluto's airglow. Although completely opaque at Lyman $\alpha$, Pluto's atmosphere is optically thin at wavelengths longer than 1425{\AA}. Consequently, a significant amount of solar FUV light reaches the surface, where it can participate in space weathering processes. From the brightness of sunlight reflected from Pluto, we find the surface has a reflectance factor (I/F) of 17% between 1400-1850{\AA}. We also report the first detection of an C$_3$ hydrocarbon molecule, methylacetylene, in absorption, at a column density of ~5$\times10^{15}$ cm$^{-2}$, corresponding to a column-integrated mixing ratio of $1.6\times10^{-6}$.

[33]  arXiv:2004.12510 [pdf, other]

Title: Self-consistent Nonlinear Force-free Field Reconstruction from Weighted Boundary Conditions

Authors: Alpha Mastrano, Kai E. Yang, Michael S. Wheatland

Comments: 12 pages, 5 figures, submitted to Solar Physics

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

Vector magnetogram data are often used as photospheric boundary conditions for force-free coronal magnetic field extrapolations. In general, however, vector magnetogram data are not consistent with the force-free assumption. In this article, we demonstrate a way to deal with inconsistent boundary data, by generalizing the "self-consistency procedure" of Wheatland & Regnier (2009). In that procedure, the inconsistency is resolved by an iterative process of constructing two solutions based on the values of the force-free parameter alpha on the two polarities of the field in the boundary (the P and N polarities), and taking uncertainty-weighted averages of the boundary alpha values in the P and N solutions. When the alpha values in the P and N regions are very different, the self-consistent solution may lose high alpha values from the boundary conditions. We show how, by altering the weighting of the uncertainties in the P or N boundary conditions, we can preserve high alpha values in the self-consistent solution. The weighted self-consistent extrapolation method is demonstrated on an analytic bipole field and applied to vector magnetogram data taken by the Helioseismic and Magnetic Imager (HMI) instrument for NOAA active region AR 12017 on 2014 March 29.

[34]  arXiv:2004.12516 [pdf, ps, other]

Title: Persistent Radio Emission from Synchrotron Heating by a Repeating Fast Radio Burst Source in a Nebula

Authors: Qiao-Chu Li, Yuan-Pei Yang, Zi-Gao Dai

Comments: 11 pages, 9 figures, accepted for publication in ApJ

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

The first repeating fast radio burst (FRB), FRB 121102, was found to be associated with a spatially coincident, persistent nonthermal radio source, but the origin of the persistent emission remains unknown. In this paper, we propose that the persistent emission is produced via synchrotron-heating process by multiple bursts of FRB 121102 in a self-absorbed synchrotron nebula. As a population of bursts of the repeating FRB absorbed by the synchrotron nebula, the energy distribution of electrons in the nebula will change significantly. As a result, the spectrum of the nebula will show a hump steadily. For the persistent emission of FRB 121102, the total energy of bursts injecting into the nebula is required to be about $3.3\times10^{49}\,\unit{erg}$, the burst injection age is over $6.7\times 10^4\,\unit{yr}$, the nebula size is $\sim0.02\,\unit{pc}$, and the electron number is about $3.2\times10^{55}$. We predict that as more bursts inject, the brightness of the nebula would be brighter than the current observation, and meanwhile, the peak frequency would become higher. Due to the synchrotron absorption of the nebula, some low-frequency bursts would be absorbed, which may explain why most bursts were detected above $\sim1~\unit{GHz}$.

[35]  arXiv:2004.12547 [pdf, other]

Title: On the Formation of SS433

Authors: Qin Han, Xiang-Dong Li (NJU)

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

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

SS433 is an extraordinary X-ray binary which is ejecting bipolar jets with $26\%$ of the speed of light. Associated with the supernova-like shell W50, SS433 is also probably one of the youngest X-ray binaries with an age of $\lesssim 10^5$ yr. However, the masses of the two components in SS433 and even the nature of the compact object are still under debate. In this work, assuming that the compact object is a black hole, we employ a binary population synthesis method to study the formation of SS433. We use previous estimates of the age of W50 and the duration of the jet activity to constrain the evolutionary history. Our calculations suggest that SS433 likely harboured a Hertzsprung gap star at the beginning of the current Roche-lobe overflow phase. The masses of the black hole and the optical/donor star in SS433 suggested by the simulations are around $8\ M_{\odot}$ and $24\ M_{\odot}$, respectively. Future measurement of the donor mass and radius can help infer not only the orgin of the binary but also the nature of the nebula W50.

[36]  arXiv:2004.12548 [pdf, other]

Title: ALMA ACA and Nobeyama observations of two Orion cores in deuterated molecular lines

Authors: Ken'ichi Tatematsu, Tie Liu, Gwanjeong Kim, Hee-Weon Yi, Jeong-Eun Lee, Naomi Hirano, Sheng-Yuan Liu, Satoshi Ohashi, Patricio Sanhueza, James Di Francesco, Neal J. Evans II, Gary A. Fuller, Ryo Kandori, Minho Choi, Miju Kang, Siyi Feng, Tomoya Hirota, Takeshi Sakai, Xing Lu, Quang Nguyen Lu'o'ng, Mark A. Thompson, Yuefang Wu, Di Li, Kee-Tae Kim, Ke Wang, Isabelle Ristorcelli, Mika Juvela, L. Viktor T'oth

Comments: 31 pages, 17 figures, 9 tables, to appear in ApJ (accepted April 23, 2020)

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

We mapped two molecular cloud cores in the Orion A cloud with the ALMA ACA 7-m Array and with the Nobeyama 45-m radio telescope. These cores have bright N$_2$D$^+$ emission in single-pointing observations with the Nobeyama 45-m radio telescope, have relatively high deuterium fraction, and are thought to be close to the onset of star formation. One is a star-forming core, and the other is starless. These cores are located along filaments observed in N$_2$H$^+$, and show narrow linewidths of 0.41 km s$^{-1}$ and 0.45 km s$^{-1}$ in N$_2$D$^+$, respectively, with the Nobeyama 45-m telescope. Both cores were detected with the ALMA ACA 7m Array in the continuum and molecular lines at Band 6. The starless core G211 shows clumpy structure with several sub-cores, which in turn show chemical differences. Also, the sub-cores in G211 have internal motions that are almost purely thermal. The starless sub-core G211D, in particular, shows a hint of the inverse P Cygni profile, suggesting infall motion. The star-forming core G210 shows an interesting spatial feature of two N$_2$D$^+$ peaks of similar intensity and radial velocity located symmetrically with respect to the single dust continuum peak. One interpretation is that the two N$_2$D$^+$ peaks represent an edge-on pseudo-disk. The CO outflow lobes, however, are not directed perpendicular to the line connecting both N$_2$D$^+$ peaks.

[37]  arXiv:2004.12579 [pdf, other]

Title: Power spectrum of halo intrinsic alignments in simulations

Authors: Toshiki Kurita, Masahiro Takada, Takahiro Nishimichi, Ryuichi Takahashi, Ken Osato, Yosuke Kobayashi

Comments: 21 pages, 17 figures

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

We use a suite of $N$-body simulations to study intrinsic alignments (IA) of halo shapes with the surrounding large-scale structure in the $\Lambda$CDM model. For this purpose, we develop a novel method to measure multipole moments of the three-dimensional power spectrum of the $E$-mode field of halo shapes with the matter/halo distribution, $P_{\delta E}^{(\ell)}(k)$ (or $P^{(\ell)}_{{\rm h}E}$), and those of the auto-power spectrum of the $E$ mode, $P^{(\ell)}_{EE}(k)$, based on the $E$/$B$-mode decomposition. The IA power spectra have non-vanishing amplitudes over the linear to nonlinear scales, and the large-scale amplitudes at $k\lesssim 0.1~h~{\rm Mpc}^{-1}$ are related to the matter power spectrum via a constant coefficient ($A_{\rm IA}$), similar to the linear bias parameter. We find that the cross- and auto-power spectra $P_{\delta E}$ and $P_{EE}$ at nonlinear scales, $k\gtrsim 0.1~h~{\rm Mpc}^{-1}$, show different $k$-dependences relative to the matter power spectrum, suggesting a violation of the nonlinear alignment model commonly used to model contaminations of cosmic shear signals. The IA power spectra exhibit baryon acoustic oscillations, and vary with halo samples of different masses, redshifts and cosmological parameters ($\Omega_{\rm m}, S_8$). The cumulative signal-to-noise ratio for the IA power spectra is about 60\% of that for the halo density power spectrum, where the super-sample covariance is found to give a significant contribution to the total covariance. Our results demonstrate that the IA power spectra of galaxy shapes, measured from imaging and spectroscopic surveys for an overlapping area of the sky, can be powerful tools to probe the underlying matter power spectrum, the primordial curvature perturbations, and cosmological parameters, in addition to the standard galaxy density power spectrum.

[38]  arXiv:2004.12589 [pdf, other]

Title: Thermal spectra of thin accretion disks of finite thickness around Kerr black holes

Authors: Menglei Zhou, Askar B. Abdikamalov, Cosimo Bambi, Ashutosh Tripathi

Comments: 7 pages, 3 figures

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

The analysis of the thermal spectrum of geometrically thin and optically thick accretion disks of black holes, the so-called continuum-fitting method, is one of the leading techniques for measuring black hole spins. Current models normally approximate the disk as infinitesimally thin, while in reality the disk thickness is finite and increases as the black hole mass accretion rate increases. Here we present an XSPEC model to calculate the multi-temperature blackbody spectrum of a thin accretion disk of finite thickness around a Kerr black hole. We test our new model with an RXTE observation of the black hole binary GRS 1915+105. We find that the spin value inferred with the new model is slightly higher than the spin value obtained with a model with an infinitesimally thin disk, but the difference is small and the effect is currently subdominant with respect to other sources of uncertainties in the final spin measurement.

[39]  arXiv:2004.12597 [pdf, other]

Title: Herschel Observations of Disks around Late-type Stars

Authors: Angelle Tanner, Peter Plavchan, Geoff Bryden, Grant Kennedy, Luca Matrá, Patrick Cronin-Coltsmann, Patrick Lowrance, Todd Henry, Basmah Riaz, John E. Gizis, Adric Riedel, Elodie Choquet

Comments: Accepted for publication in PASP

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

A set of twenty late-type (K5-M5) stars were observed with the Herschel Space Observatory at 100 and 160 microns with the goal of searching for far-infrared excesses indicative of the presence of circumstellar disks. Out of this sample, four stars (TYC 7443-1102-1, TYC 9340-437-1, GJ 784 and GJ 707) have infrared excesses above their stellar photospheres at either 100 or 160 micron or both. At 100 microns TYC 9340-437-1 is spatially resolved with a shape that suggests it is surrounded by a face-on disk. The 100 micron excess flux associated with GJ 707 is marginal at around 3sigma. The excess flux associated with GJ 784 is most likely due to a background galaxy as the dust radius estimated from the spectral energy fit implies that any associated dust disk should have been resolved in the Herschel images but is not. TYC 7443-1102-1 has been observed with ALMA which resolves the emission at its location into two distinct sources making the Herschel excess most likely also due to a background galaxy. It is worth noting that this star is in the 23 Myr old beta Pic association. With a disk luminosity on the order of 10^-3 L*, this system is an ideal follow-up target for high-contrast imaging and ALMA.

[40]  arXiv:2004.12612 [pdf, ps, other]

Title: Radiative equilibrium estimates of dust temperature and mass in high-redshift galaxies

Authors: Akio K. Inoue (1), Takuya Hashimoto (2), Hiroki Chihara (3), Chiyoe Koike (3) ((1) Waseda University, (2) Tsukuba University, (3) Osaka Sangyo University)

Comments: MNRAS accepted

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

Estimating the temperature and mass of dust in high-$z$ galaxies is essential for discussions of the origin of dust in the early Universe. However, this suffers from limited sampling of the infrared spectral-energy distribution. Here we present an algorithm for deriving the temperature and mass of dust in a galaxy, assuming dust to be in radiative equilibrium. We formulate the algorithm for three geometries: a thin spherical shell, a homogeneous sphere, and a clumpy sphere. We also discuss effects of the mass absorption coefficients of dust at ultraviolet and infrared wavelengths, $\kappa_{\rm UV}$ and $\kappa_{\rm IR}$, respectively. As an example, we apply the algorithm to a normal, dusty star-forming galaxy at $z=7.5$, A1689zD1, for which three data points in the dust continuum are available. Using $\kappa_{\rm UV}=5.0\times10^4$ cm$^2$ g$^{-1}$ and $\kappa_{\rm IR}=30(\lambda/100\mu m)^{-\beta}$ cm$^2$ g$^{-1}$ with $\beta=2.0$, we obtain dust temperatures of 38--70~K and masses of $10^{6.5-7.3}$ M$_\odot$ for the three geometries considered. We obtain similar temperatures and masses from just a single data point in the dust continuum, suggesting the usefulness of the algorithm for high-$z$ galaxies with limited infrared observations. In the clumpy-sphere case, the temperature becomes equal to that of the usual modified black-body fit, because an additional parameter describing the clumpiness works as an adjuster. The best-fit clumpiness parameter is $\xi_{\rm cl}=0.1$, corresponding to $\sim10$\% of the volume filling factor of the clumps in this high-$z$ galaxy if the clump size is $\sim10$ pc, similar to that of giant molecular clouds in the local Universe.

[41]  arXiv:2004.12622 [pdf, other]

Title: The K supergiant runaway star HD 137071

Authors: F. Comerón, F. Figueras

Comments: 6 pages, 4 figures. To be published in Astronomy and Astrophysics

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

Very few examples are known of red supergiant runaways, all of them descending from the more massive O-type precursors, but none from the lower mass B-type precursors, although runaway statistics among B-type stars suggest that K-type runaways must be relatively numerous. We study HD 137071, a star that has been considered so far as a normal K-type red giant. Its parallax measured by Gaia and the derived luminosity suggest that it is actually a supergiant, whereas its derived distance to the galactic plane and its spatial velocity of 54.1 km s$^{-1}$ with respect to the local standard of rest suggest that it is also a runaway star. However, intrinsic limitations in determining the trigonometric parallaxes of cool supergiants, even in the Gaia era, require accurate spectral classifications for confirmation. We reliably classify HD 137071 as a K4II star establishing its membership to the extreme Population I, which is in agreement with the luminosity derived using the Gaia DR2 parallax measurement. Kinematical data from the Gaia DR2 catalog confirm its high spatial velocity and its runaway nature. Combining the spectral classification with astrometric information, a state-of-the-art galactic potential model, and evolutionary models for high-mass stars we trace the motion of HD 137071 back to the proximities of the galactic plane and speculate on which of the two proposed mechanisms for the production of runaway stars may be responsible for the high velocity of HD 137071. The available data favor the formation of HD 137071 in a massive binary system where the more massive companion underwent a supernova explosion about 32 Myr ago.

[42]  arXiv:2004.12641 [pdf, other]

Title: The extended Gaia-PS1-SDSS (GPS1+) proper motion catalog

Authors: Hai-Jun Tian, Yang Xu, Chao Liu, Hans-Walter Rix, Branimir Sesar, Bertrand Goldman

Comments: 10 pages, 9 figues, 2 tables, accepted for publication on ApJS

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

The GPS1 catalog was released in 2017. It delivered precise proper motions for around 350 million sources across three-fourths of the sky down to a magnitude of $r\sim20$\,mag. In this study, we present GPS1+ the extension GPS1 catalog down to $r\sim22.5$\,mag, based on {\it Gaia} DR2, PS1, SDSS and 2MASS astrometry. The GPS1+ totally provides proper motions for $\sim$400 million sources with a characteristic systematic error of less than 0.1\masyr. This catalog is divided into two sub-samples, i.e., the primary and secondary parts. The primary $\sim$264 million sources have either or both of the {\it Gaia} and SDSS astrometry, with a typical precision of 2.0-5.0 \masyr. In this part, $\sim$160 million sources have {\it Gaia} proper motions, we provide another new proper motion for each of them by building a Bayesian model. Relative to {\it Gaia}'s values, the precision is improved by $\sim$0.1\,dex on average at the faint end; $\sim$50 million sources are the objects whose proper motions are missing in {\it Gaia} DR2, we provide their proper motion with a precision of $\sim$4.5\masyr; the remaining $\sim$54 million faint sources are beyond {\it Gaia} detecting capability, we provide their proper motions for the first time with a precision of 7.0 \masyr. However, the secondary $\sim$136 million sources only have PS1 astrometry, the average precision is worse than 15.0 \masyr. All the proper motions have been validated using QSOs and the existing {\it Gaia} proper motions. The catalog will be released on-line and available via the VO-TAP Service.

[43]  arXiv:2004.12649 [pdf, other]

Title: A New Method to Measure Hubble Parameter $H(z)$ using Fast Radio Bursts

Authors: Q. Wu, Hai Yu, F. Y. Wang (NJU)

Comments: 10 pages, 4 figures, accepted for publication in ApJ

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

The Hubble parameter $H(z)$ is directly related to the expansion of our Universe. It can be used to study dark energy and constrain cosmology models. In this paper, we propose that $H(z)$ can be measured using fast radio bursts (FRBs) with redshift measurements. We use dispersion measures contributed by the intergalactic medium, which is related to $H(z)$, to measure Hubble parameter. We find that 500 mocked FRBs with dispersion measures and redshift information can accurately measure Hubble parameters using Monte Carlo simulation. The maximum deviation of $H(z)$ from standard $\Lambda$CDM model is about 6\% at redshift $z= 2.4$. We also test our method using Monte Carlo simulation. Kolmogorov-Smirnov (K-S) test is used to check the simulation. The $p$-value of K-S test is 0.23, which confirms internal consistency of the simulation. In future, more localizations of FRBs make it as an attractive cosmological probe.

[44]  arXiv:2004.12659 [pdf, other]

Title: A study on Cubic Galileon Gravity Using N-body Simulations

Authors: Jiajun Zhang, Bikash R. Dinda, Md. Wali Hossain, Anjan A. Sen, Wentao Luo

Comments: 19 pages, 12 figures, submitted to PRD

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

We use N-body simulation to study the structure formation in the Cubic Galileon Gravity model where along with the usual kinetic and potential term we also have a higher derivative self-interaction term. We find that the large scale structure provides a unique constraining power for this model. The matter power spectrum, halo mass function, galaxy-galaxy weak lensing signal, marked density power spectrum as well as count in cell are measured. The simulations show that there are less massive halos in the Cubic Galileon Gravity model than corresponding $\Lambda$CDM model and the marked density power spectrum in these two models are different by more than $10\%$. Furthermore, the Cubic Galileon model shows significant differences in voids compared to $\Lambda$CDM. The number of low density cells is far higher in the Cubic Galileon model than that in the $\Lambda$CDM model. Therefore, it would be interesting to put constraints on this model using future large scale structure observations, especially in void regions.

[45]  arXiv:2004.12663 [pdf, ps, other]

Title: Observational features of exoplanetary synchrotron radio bursts

Authors: Yang Gao (SYSU), Lei Qian (NAOC), Di Li (NAOC)

Comments: Accepted for publication in ApJ, 3 figures

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

Magnetic fields of exoplanets are important in shielding the planets from cosmic rays and interplanetary plasma. Due to the interaction with the electrons from their host stars, the exoplanetary magnetospheres are predicted to have both cyclotron and synchrotron radio emissions, of which neither has been definitely identified in observations yet. As the coherent cyclotron emission has been extensively studied in literatures, here we focus on the planetary synchrotron radiation with bursty behaviors (i.e., radio flares) caused by the outbreaks of energetic electron ejections from the host star. Two key parameters of the bursty synchrotron emissions, namely the flux density and burst rate, and two key features namely the burst light curve and frequency shift, are predicted for star - hot Jupiter systems. The planetary orbital phase - burst rate relation is also considered as the signature of star-planet interactions (SPI). As examples, previous X-ray and radio observations of two well studied candidate systems, HD 189733 and V830 \tau, are adopted to predict their specific burst rates and fluxes of bursty synchrotron emissions for further observational confirmations. The detectability of such emissions by current and upcoming radio telescopes shows that we are at the dawn of discoveries.

[46]  arXiv:2004.12666 [pdf, other]

Title: The RAdial Velocity Experiment: Parameterization of RAVE spectra based on Convolutional Neural Network

Authors: G. Guiglion, G. Matijevic, A. B. A. Queiroz, M. Valentini, M. Steinmetz, C. Chiappini, E. K. Grebel, P. J. McMillan, G. Kordopatis, A. Kunder, T. Zwitter, A. Khalatyan, F. Anders, H. Enke, I. Minchev, G. Monari, R. F. G. Wyse, O. Bienayme, J. Bland-Hawthorn, B. K. Gibson, J. F. Navarro, Q. Parker, W. Reid, G. M. Seabroke, A. Sieber

Comments: 30 pages, 29 figures, submitted to A&A

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

Data-driven methods play an increasingly important role in the field of astrophysics. In the context of large spectroscopic surveys of stars, data-driven methods are key in deducing physical parameters for millions of spectra in a short time. Convolutional Neural Networks (CNNs) enable us to connect observables (e.g., spectra, stellar magnitudes) to physical properties (atmospheric parameters, chemical abundances, or labels in general). We trained a CNN, adopting stellar atmospheric parameters and chemical abundances from APOGEE DR16 (resolution R~22500) data as training set labels. As input we used parts of the intermediate-resolution RAVE DR6 spectra (R~7500) overlapping with the APOGEE DR16 data as well as broad-band ALL_WISE and 2MASS photometry together with Gaia DR2 photometry and parallaxes. We derived precise atmospheric parameters Teff, log(g), [M/H] and chemical abundances of [Fe/H], [alpha/M], [Mg/Fe], [Si/Fe], [Al/Fe], and [Ni/Fe] for 420165 RAVE spectra. The precision typically amounts to 60K in Teff, 0.06 in log(g), and 0.02-0.04 dex for individual chemical abundances. Incorporating photometry and astrometry as additional constraints substantially improves the results in terms of accuracy and precision of the derived labels, as long as we operate in parts of the parameter space that is well covered by the training sample. Scientific validation confirms the robustness of the CNN results. We provide a catalog of CNN-trained atmospheric parameters and abundances along with their uncertainties for 420165 stars in the RAVE survey. CNN-based methods provide a powerful way to combine spectroscopic, photometric, and astrometric data, without applying any priors in the form of stellar evolutionary models. The developed procedure can extend the scientific output of RAVE spectra beyond DR6 to on-going and planned surveys such as Gaia RVS and 4MOST.

[47]  arXiv:2004.12688 [pdf, other]

Title: $^{44}\rm Ti$ ejecta in young supernova remnants

Authors: Christoph Weinberger (1), Roland Diehl (1), Moritz M. M. Pleintinger (1), Thomas Siegert (2), Jochen Greiner (1) ((1) Max-Planck-Institut für extraterrestrische Physik, Gießenbachstraße, (2) Center for Astrophysics and Space Sciences, University of California, San Diego)

Comments: 15 pages, 11 figures, Accepted for publication in A&A

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

Context: Tracing unstable isotopes produced in supernova nucleosynthesis provides a direct diagnostic of supernova explosion physics. Theoretical models predict an extensive variety of scenarios, which can be constrained through observations of the abundant isotopes $^{56}$Ni and $^{44}$Ti. Direct evidence of the latter was previously found only in two core-collapse supernova events, and appears to be absent in thermonuclear supernovae.Aims: We aim to to constrain the supernova progenitor types of Cas A, SN 1987A, Vela Jr., G1.9+0.3, SN1572, and SN1604 through their $^{44}$Ti ejecta masses and explosion kinematics. Methods: We analyzed INTEGRAL/SPI observations of the candidate sources utilizing an empirically motivated high-precision background model. We analyzed the three dominant spectroscopically resolved de-excitation lines at 68, 78, and 1157\,keV emitted in the decay chain of $^{44}$Ti. The fluxes allow the determination of the production yields of $^{44}$Ti. Remnant kinematics were obtained from the Doppler characteristics of the lines. Results: We find a significant signal for Cas A in all three lines with a combined significance of 5.4$\sigma$. The fluxes are $(3.3 \pm 0.9) \times 10^{-5}$ ph cm$^{-2}$ s$^{-1}$, and $(4.2 \pm 1.0) \times 10^{-5}$ ph cm$^{-2}$ s$^{-1}$ for the $^{44}$Ti and $^{44}$Sc decay, respectively. We obtain higher fluxes for $^{44}$Ti with our analysis of Cas A than were obtained in previous analyses. We discuss potential differences. Conclusions: We obtain a high $^{44}$Ti ejecta mass for Cas A that is in disagreement with ejecta yields from symmetric 2D models. Upper limits for the other core-collapse supernovae are in agreement with model predictions and previous studies. The upper limits we find for the three thermonuclear supernovae consistently exclude the double detonation and pure helium deflagration models as progenitors.

[48]  arXiv:2004.12708 [pdf, other]

Title: Time-Distance Helioseismology of Deep Meridional Circulation

Authors: S.P. Rajaguru (1), H.M. Antia (2) ((1) Indian Institute of Astrophysics, Bangalore, India (2) Tata Institute of Fundamental Research, Mumbai, India)

Comments: 6 pages, 3 figures, to appear in the Springer series Astrophysics and Space Science Proceedings of "Dynamics of the Sun & Stars: Honoring the Life & Work of Michael Thompson" (2020)

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

A key component of solar interior dynamics is the meridional circulation (MC), whose poleward component in the surface layers has been well observed. Time-distance helioseismic studies of the deep structure of MC, however, have yielded conflicting inferences. Here, following a summary of existing results we show how a large center-to-limb systematics (CLS) in the measured travel times of acoustic waves affect the inferences through an analysis of frequency dependence of CLS, using data from the Helioseismic and Doppler Imager (HMI) onboard Solar Dynamics Observatory (SDO). Our results point to the residual systematics in travel times as a major cause of differing inferences on the deep structure of MC.

[49]  arXiv:2004.12718 [pdf, other]

Title: Prospects for High-Elevation Radio Detection of >100 PeV Tau Neutrinos

Authors: Stephanie Wissel, Andrés Romero-Wolf, Harm Schoorlemmer, Washington R. Carvalho Jr., Jaime Alvarez-Muñiz, Enrique Zas, Austin Cummings, Cosmin Deaconu, Kaeli Hughes, Andrew Ludwig, Joalda Morancy, Eric Oberla, Caroline Paciaroni, Steven Prohira, Dan Southall, Max Stapel-Kalat, Ben Strutt, Mercedes Vasquez, Abigail Vieregg

Comments: 25 pages, 11 figures

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

Tau neutrinos are expected to comprise roughly one third of both the astrophysical and cosmogenic neutrino flux, but currently the flavor ratio is poorly constrained and the expected flux at energies above $10^{17}$ eV is low. We present a detector concept aimed at measuring the diffuse flux of tau neutrinos in this energy range via a high-elevation mountaintop detector using the radio technique. The detector searches for radio signals from upgoing air showers generated by Earth-skimming tau neutrinos. Signals from several antennas in a compact array are coherently summed at the trigger level, permitting not only directional masking of anthropogenic backgrounds, but also a low trigger threshold. This design takes advantage of both the large viewing area available at high-elevation sites and the nearly full duty cycle available to radio instruments. We present trade studies that consider the station elevation, frequency band, number of antennas in the array, and the trigger threshold to develop a highly efficient station design. Such a mountaintop detector can achieve a factor of ten improvement in acceptance over existing instruments with 100 independent stations. With 1000 stations and three years of observation, it can achieve a sensitivity to an integrated $\mathcal{E}^{-2}$ flux of $<10^{-9}$ GeV cm$^{-2}$ sr$^{-1}$ s$^{-1}$, in the range of the expected flux of all-flavor cosmogenic neutrinos assuming a pure iron cosmic-ray composition.

[50]  arXiv:2004.12748 [pdf, ps, other]

Title: Optical spectral properties of radio loud quasars along the main sequence

Authors: A. del Olmo, P. Marziani, V. Ganci, M. D'Onofrio, E. Bon, N. Bon, A. C. Negrete

Comments: 3 pages, 2 figures; Proceedings paper of the IAU symposium 356 "Nuclear Activity in Galaxies Across Cosmic Time" (Ethiopia) accepted to be published under the Cambridge University Press, eds. M. Povic, P. Marziani, J. Masegosa, H. Netzer, S. H. Negu, and S. B. Tessema

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

We analyze the optical properties of Radio-Loud quasars along the Main Sequence (MS) of quasars. A sample of 355 quasars selected on the basis of radio detection was obtained by cross-matching the FIRST survey at 20cm and the SDSS DR12 spectroscopic survey. We consider the nature of powerful emission at the high-FeII end of the MS. At variance with the classical radio-loud sources which are located in the Population B domain of the MS optical plane, we found evidence indicating a thermal origin of the radio emission of the highly accreting quasars of Population A.

[51]  arXiv:2004.12808 [pdf, ps, other]

Title: To power the X-ray plateaus of gamma-ray bursts through larger amplitude electromagnetic waves

Authors: Shuang Du, Fangkun Peng, Renxin Xu

Comments: 8 pages, 2 figures, ApJ submitted

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

The origin of gamma-ray burst (GRB) X-ray plateau, especially the internal plateau is still unclear, but could be related to GRB's central engine of magnetar. It is generally believed that the spin-down power of the magnetar is injected into forward external shock, however we propose here that most of the power will be dissipated behind the GRB jet through larger amplitude electromagnetic wave (LAEMW). The relevant physical conditions and observational implications are analyzed and discussed, and various kinds of X-ray light curves could be reproduced. Although it is still a matter of debate about the chromatic multi-band afterglow in the standard external afterglow fireball model, we can explain naturally this feature under this scenario. Furthermore, we predict that the X-ray emission of spin-down wind could possibly precede the prompt emission of GRB jet if the energy of LAEMW is dissipated first but shock-induced radiation in the jet is produced later. It is emphasized that both the GRB jet and the spin-down wind should have significant observational consequences in the magnetar scenario, and would be focused equally in GRB physics.

[52]  arXiv:2004.12812 [pdf, other]

Title: A He I upper atmosphere around the warm Neptune GJ 3470b

Authors: E. Palle, L. Nortmann, N. Casasayas-Barris, M. Lampón, M. López-Puertas, J. A. Caballero, J. Sanz-Forcada, L. M. Lara, E. Nagel, F. Yan, F. J. Alonso-Floriano, P. J. Amado, G. Chen, C. Cifuentes, M. Cortés-Contreras, S. Czesla, K. Molaverdikhani, D. Montes, V. M. Passegger, A. Quirrenbach, A. Reiners, I. Ribas, A. Sánchez-López, A. Schweitzer, M. Stangret, M. R. Zapatero Osorio, M. Zechmeister

Comments: Accepted for publication in A&A

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

High resolution transit spectroscopy has proven to be a reliable technique for the characterization of the chemical composition of exoplanet atmospheres. Taking advantage of the broad spectral coverage of the CARMENES spectrograph, we initiated a survey aimed at characterizing a broad range of planetary systems. Here, we report our observations of three transits of \tplanet with CARMENES in search of \het\ absorption. On one of the nights, the He~{\sc i} region was heavily contaminated by OH$^-$ telluric emission and, thus, it was not useful for our purposes. The remaining two nights had a very different signal-to-noise ratio (S/N) due to weather. They both indicate the presence of \het\ absorption in the transmission spectrum of \tplanet, although a statistically valid detection can only be claimed for the night with higher S/N. For that night, we retrieved a 1.5$\pm$0.3\% absorption depth, translating into a $R_p(\lambda)/R_p = 1.15\pm 0.14$ at this wavelength. Spectro-photometric light curves for this same night also indicate the presence of extra absorption during the planetary transit with a consistent absorption depth. The \het\ absorption is modeled in detail using a radiative transfer code, and the results of our modeling efforts are compared to the observations. We find that the mass-loss rate, \mlr, is confined to a range of 3\,$\times\,10^{10}$\,\gs\ for $T$ = 6000\,K to 10\,$\times\,10^{10}$\,\gs\ for $T$ = 9000\,K. We discuss the physical mechanisms and implications of the He~{\sc i} detection in \tplanet and put it in context as compared to similar detections and non-detections in other Neptune-size planets. We also present improved stellar and planetary parameter determinations based on our visible and near-infrared observations.

[53]  arXiv:2004.12829 [pdf, other]

Title: WISEA J083011.95+283716.0: A Missing Link Planetary-Mass Object

Authors: Daniella C. Bardalez Gagliuffi, Jacqueline K. Faherty, Adam C. Schneider, Aaron Meisner, Dan Caselden, Guilluame Colin, Sam Goodman, J. Davy Kirkpatrick, Marc Kuchner, Jonathan Gagné, Sarah E. Logsdon, Adam J. Burgasser, Katelyn Allers, John Debes, John Wisniewski, Austin Rothermich, Nikolaj Stevnbak Andersen, Melina Thévenot, Jim Walla

Comments: 13 pages, 6 figures, 5 tables

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

We present the discovery of WISEA J083011.95+283716.0, the first Y dwarf candidate identified through the Backyard Worlds: Planet 9 citizen science project. We identified this object as a red, fast-moving source with a faint $W2$ detection in multi-epoch \textit{AllWISE} and unWISE images. We have characterized this object with Spitzer Space Telescope and \textit{Hubble Space Telescope} follow-up imaging. With mid-infrared detections in \textit{Spitzer}'s \emph{ch1} and \emph{ch2} bands and flux upper limits in Hubble Space Telescope $F105W$ and $F125W$ filters, we find that this object is both very faint and has extremely red colors ($ch1-ch2 = 3.25\pm0.23$ mag, $F125W-ch2 \geq 9.36$ mag), consistent with a T$_{eff}\sim300$ K source, as estimated from the known Y dwarf population. A preliminary parallax provides a distance of $11.1^{+2.0}_{-1.5}$ pc, leading to a slightly warmer temperature of $\sim350$ K. The extreme faintness and red Hubble Space Telescope and Spitzer Space Telescope colors of this object suggest it may be a link between the broader Y dwarf population and the coldest known brown dwarf WISE J0855$-$0714, and highlight our limited knowledge of the true spread of Y dwarf colors. We also present four additional Backyard Worlds: Planet 9 late-T brown dwarf discoveries within 30 pc.

[54]  arXiv:2004.12872 [pdf, other]

Title: Ions in the Thermosphere of Exoplanets: Observable Constraints Revealed by Innovative Laboratory Experiments

Authors: Jérémy Bourgalais, Nathalie Carrasco, Quentin Changeat, Olivia Venot, Lora Jovanović, Pascal Pernot, Jonathan Tennyson, Katy L. Chubb, Sergey N. Yurchenko, Giovanna Tinetti

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

With the upcoming launch of space telescopes dedicated to the study of exoplanets, the \textit{Atmospheric Remote-Sensing Infrared Exoplanet Large-survey} (ARIEL) and the \textit{James Webb Space Telescope} (JWST), a new era is opening in the exoplanetary atmospheric explorations. However, especially in relatively cold planets around later-type stars, photochemical hazes and clouds may mask the composition of the lower part of the atmosphere, making it difficult to detect any chemical species in the troposphere or to understand whether there is a surface or not. This issue is particularly exacerbated if the goal is to study the habitability of said exoplanets and to search for biosignatures.\par This work combines innovative laboratory experiments, chemical modeling and simulated observations at ARIEL and JWST resolutions. We focus on the signatures of molecular ions that can be found in upper atmospheres above cloud decks. Our results suggest that H$_3^+$ along with H$_3$O$^+$ could be detected in the observational spectra of sub-Neptunes based on realistic mixing ratio assumption. This new parametric set may help to distinguish super-Earths with a thin atmosphere from H$_2$-dominated sub-Neptunes, to address the critical question whether a low-gravity planet around a low-mass active star is able to retain its volatile components. These ions may also constitute potential tracers to certain molecules of interest such as H$_2$O or O$_2$ to probe the habitability of exoplanets. Their detection will be an enthralling challenge for the future JWST and ARIEL telescopes.

[55]  arXiv:2004.12878 [pdf, other]

Title: K-Stacker, an algorithm to hack the orbital parameters of planets hidden in high-contrast imaging. First applications to VLT SPHERE multi-epoch observations

Authors: H. Le Coroller, M. Nowak, P. Delorme, G. Chauvin, R. Gratton, M. Devinat, J. Bec-Canet, A. Schneeberger, D. Estevez, L. Arnold, H. Beust, M. Bonnefoy, A. Boccaletti, C. Desgrange, S. Desidera, R. Galicher, A.M. Lagrange, M. Langlois, A.L. Maire, F. Menard, P. Vernazza, A. Vigan, A. Zurlo, T. Fenouillet, J.C. Lambert, M. Bonavita, A. Cheetham, V. Dorazi, M. Feldt, M. Janson, R. Ligi, D. Mesa, M. Meyer, M. Samland, E. Sissa, J.L. Beuzit, K. Dohlen, T. Fusco, D. Le Mignant, D. Mouillet, J. Ramos, S. Rochat, J.F. Sauvage

Comments: Astronomy & Astrophysics accepted, 13 Pages, 11 Figures

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

Recent high-contrast imaging surveys, looking for planets in young, nearby systems showed evidence of a small number of giant planets at relatively large separation beyond typically 20 au where those surveys are the most sensitive. Access to smaller physical separations between 5 and 20 au is the next step for future planet imagers on 10 m telescopes and ELTs in order to bridge the gap with indirect techniques (radial velocity, transit, astrometry with Gaia). In that context, we recently proposed a new algorithm, Keplerian-Stacker, combining multiple observations acquired at different epochs and taking into account the orbital motion of a potential planet present in the images to boost the ultimate detection limit. We showed that this algorithm is able to find planets in time series of simulated images of SPHERE even when a planet remains undetected at one epoch. Here, we validate the K-Stacker algorithm performances on real SPHERE datasets, to demonstrate its resilience to instrumental speckles and the gain offered in terms of true detection. This will motivate future dedicated multi-epoch observation campaigns in high-contrast imaging to search for planets in emitted and reflected light. Results. We show that K-Stacker achieves high success rate when the SNR of the planet in the stacked image reaches 7. The improvement of the SNR ratio goes as the square root of the total exposure time. During the blind test and the redetection of HD 95086 b, and betaPic b, we highlight the ability of K-Stacker to find orbital solutions consistent with the ones derived by the state of the art MCMC orbital fitting techniques, confirming that in addition to the detection gain, K-Stacker offers the opportunity to characterize the most probable orbital solutions of the exoplanets recovered at low signal to noise.

[56]  arXiv:2004.12882 [pdf, other]

Title: The hidden companion in LB-1 unveiled by spectral disentangling

Authors: T. Shenar, J. Bodensteiner, M. Abdul-Masih, M. Fabry, L. Mahy, P. Marchant, G. Banyard, D. M. Bowman, K. Dsilva, C. Hawcroft, M. Reggiani, H. Sana

Comments: Submitted to A&A. 5 pages (4 figures, 1 table); 2 pages of supporting material (3 figures and 1 table)

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

The intriguing binary LS V + 22 25 (LB-1) drew much attention after being claimed to be a 79-day binary comprising a B-type star orbiting a ~70Ms black hole - the most massive stellar black hole reported to date. Subsequent studies showed that evidence for such a large companion mass is lacking. Recent analyses implied that the primary star is a stripped, He-rich star with peculiar sub-solar abundances of heavy elements such as Mg and Fe. However, the nature of the secondary, which was proposed to be a black hole, a neutron star, or a main sequence star, remains unknown. Relying on 26 newly acquired spectroscopic observations secured with the HERMES and FEROS spectrographs, we perform an orbital analysis and spectral disentangling of LB-1 to elucidate the nature of the system.
We find that LB-1 contains two non-degenerate stars. The "hidden" secondary is a rapidly rotating (vsini ~ 300 km/s) B3 V star with a decretion disk - a Be star. The properties of the primary match those predicted for stripped stars: it is He- and N-rich and portrays significant Balmer-line emission, presumably stemming from its wind. Adopting a light contribution in the optical of 55% for the stripped primary, the abundances of heavy elements are found to be solar. With the derived value of K2 = 11.2 +- 1.0 km/s and by calibrating the mass of the B3 Ve secondary to M2 = 7 +- 2Ms, we derive an orbital mass for the stripped primary of M1 = 1.5 +- 0.4Ms. The orbital inclination of 39 +- 4deg implies a near-critical rotation for the Be secondary Veq ~ 470 km/s.
Hence, LB-1 does not contain a compact object. Instead, it is a rare Be binary system consisting of a stripped donor star and a Be mass accretor rotating at near its critical velocity. This system is a clear example that binary interactions play a decisive role in the production of rapid stellar rotators and Be stars.

[57]  arXiv:2004.12899 [pdf, other]

Title: Proper motion measurements for stars up to $100$ kpc with Subaru HSC and SDSS Stripe 82

Authors: Tian Qiu, Wenting Wang, Masahiro Takada, Naoki Yasuda, Željko Ivezić, Robert H. Lupton, Masashi Chiba, Miho Ishigaki, Yutaka Komiyama

Comments: submitted to MNRAS

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

We present proper motion measurements for more than $0.55$ million main-sequence stars, by comparing astrometric positions of matched stars between the multi-band imaging datasets from the Hyper Suprime-Cam (HSC) Survey and the SDSS Stripe 82. In doing this we use $3$ million galaxies to recalibrate the astrometry and set up a common reference frame between the two catalogues. The exquisite depth and the nearly $12$ years of time baseline between HSC and SDSS enable high-precision measurements of statistical proper motions for stars down to $i\simeq 24$. A validation of our method is demonstrated by the agreement with the $Gaia$ proper motions, to the precision better than $0.1$ mas yr$^{-1}$. To retain the precision, we make a correction of the subtle effects due to the differential chromatic refraction in the SDSS images based on the comparison with the $Gaia$ proper motions against colour of stars, which is validated using the SDSS spectroscopic quasars. Combining with the photometric distance estimates for individual stars based on the precise HSC photometry, we show a significant detection of the net proper motions for stars in each bin of distance out to $100$ kpc. The two-component tangential velocities after subtracting the apparent motions due to our own motion display rich phase-space structures including a clear signature of the Sagittarius stream in the halo region of distance range $[10,\ 35]$ kpc. We also measure the tangential velocity dispersion in the distance range $5-20$ kpc and find that the data are consistent with a constant isotropic dispersion of $80\pm 10\ {\rm km/s}$. More distant stars appear to have random motions with respect to the Galactic centre on average.

[58]  arXiv:2004.12900 [pdf, ps, other]

Title: On the effects of UV photons/X-rays on the chemistry of the Sgr B2 cloud

Authors: J. Armijos-Abendaño, J. Martín-Pintado, E. López, M. Llerena, N. Harada, M. A. Requena-Torres, S. Martín, V. M. Rivilla, D. Riquelme, F. Aldas

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

The lines of HOC$^+$, HCO and CO$^+$ are considered good tracers of photon-dominated regions (PDRs) and X-ray dominated regions. We study these tracers towards regions of the Sgr B2 cloud selected to be affected by different heating mechanisms. We find the lowest values of the column density ratios of HCO$^+$ versus HOC$^+$, HCO and CO$^+$ in dense HII gas, where UV photons dominate the heating and chemistry of gas. HOC$^+$, HCO and CO$^+$ abundances and the above ratios are compared with those of chemical modeling, finding that high temperature chemistry, a cosmic-ray ionization rate of 10$^{-16}$ s$^{-1}$ and timescales $>$10$^{5.0}$ years explain well the HOC$^+$ abundances in quiescent Sgr B2 regions, while shocks are also needed to explain the highest HCO abundances derived for these regions. CO$^+$ is mainly formed in PDRs since the highest CO$^+$ abundances of $\sim$(6-10)$\times$10$^{-10}$ are found in HII regions with electron densities $>$540 cm$^{-3}$ and that CO$^+$ emission is undetected in quiescent gas. Between the ratios, the HCO$^+$/HCO ratio is sensitive to the electron density as it shows different values in dense and diffuse HII regions. We compare SiO J=2-1 emission maps of Sgr B2 with X-ray maps from 2004 and 2012. One known spot shown on the 2012 X-ray map is likely associated with molecular gas at velocities of 15-25 km s$^{-1}$. We also derive the X-ray ionization rate of $\sim$10$^{-19}$ s$^{-1}$ for Sgr B2 regions pervaded by X-rays in 2004, which is quite low to affect the chemistry of the molecular gas.

[59]  arXiv:2004.12907 [pdf, other]

Title: Photometric Limits on the High Resolution Imaging of Exoplanets Using the Solar Gravity Lens

Authors: Phil A. Willems (Jet Propulsion Laboratory, California Institute of Technology)

Journal-ref: Acta Astronautica vol. 152, pp. 408-414 (2018)

Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR); General Relativity and Quantum Cosmology (gr-qc)

We present an analysis of high-resolution imaging of an exoplanet by a telescope positioned at a real image of the exoplanet created by the solar gravity lens. We assume an exoplanet viewed in full phase and a simple deconvolution method to correct for the intrinsic blur caused by aberrations in the solar gravity lens, and account for the foreground light of the solar corona. We derive equations for the measurement times required to produce such a high-resolution image, and find that due to shot noise considerations these times are large compared to human lifespans. We also discuss how measurement times could potentially be significantly shorter for exoplanets with special orbital and rotational parameters.

[60]  arXiv:2004.12924 [pdf, other]

Title: Unveiling pure-metal ejecta X-ray emission in supernova remnants through their radiative recombination continuum

Authors: Emanuele Greco, Jacco Vink, Marco Miceli, Salvatore Orlando, Vladimir Domcek, Ping Zhou, Fabrizio Bocchino, Giovanni Peres

Comments: 13 pages, 12 figures, accepted for publication in A&A

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

Spectral analysis of X-ray emission from ejecta in supernova remnants (SNRs) is hampered by the low spectral resolution of CCD cameras, which creates a degeneracy between the best-fit values of abundances and emission measure. The combined contribution of shocked ambient medium and ejecta to the X-ray emission complicates the determination of the ejecta mass and chemical composition, leading to big uncertainties in mass estimates and it can introduce a bias in the comparison between the observed ejecta composition and the yields predicted by explosive nucleosynthesis. We explore the capabilities of present and future spectral instruments with the aim of identifying a spectral feature which may allow us to discriminate between metal-rich and pure-metal plasmas in X-ray spectra of SNRs. We studied the behavior of the most common X-ray emission processes of an optically thin plasma in the high-abundance regime. We investigated spectral features of bremsstrahlung, radiative recombination continua (RRC) and line emission, by exploring a wide range of chemical abundances, temperatures and ionization parameters. We synthesized X-ray spectra from a 3D hydrodynamic (HD) simulation of Cas A, by using the response matrix from the Chandra/ACIS-S CCD detector and that of the XRISM/Resolve X-ray calorimeter. We found that a bright RRC shows up when the plasma is made of pure-metal ejecta, and a high spectral resolution is needed to identify this ejecta signature. We verified the applicability of our novel diagnostic tool and we propose a promising target for the future detection of such spectral feature: the southeastern Fe-rich clump of Cas A. While there is no way to unambiguously reveal pure-metal ejecta emission with CCD detectors, X-ray calorimeters will be able to pinpoint the presence of pure-metal RRC and to recover correctly absolute mass and the chemical composition of the ejecta.

[61]  arXiv:2004.12938 [pdf, other]

Title: Molecular globules in Orion's Veil bubble. IRAM 30m 12CO, 13CO, and C18O 2-1 expanded maps of Orion A

Authors: J. R. Goicoechea, C. H. M. Pabst, S. Kabanovic, M. G. Santa-Maria, N. Marcelino, A. G. G. M. Tielens, A. Hacar, O. Berne, C. Buchbender, S. Cuadrado, R. Higgins, C. Kramer, J. Stutzki, S. Suri, D. Teyssier, M. Wolfire

Comments: Accepted for publication in A&A. (Abridged abstract. English not edited. Some figures have been bitmapped to lower resolution)

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

Strong winds and ultraviolet (UV) radiation from O-type stars disrupt and ionize their molecular core birthplaces sweeping up material into parsec size shells. Owing to dissociation by starlight, the thinnest shells are expected to host low molecular abundances; thus, little star-formation. Here we enlarge previous observations taken with the IRAM 30m telescope and present square-degree 12CO and 13CO (J=2-1) maps of the wind-driven "Veil bubble" that surrounds the Trapezium cluster and its natal Orion molecular core (OMC). Although widespread and extended CO emission is largely absent from the Veil, we show that several CO "globules" exist embedded in the [CII]158um-bright shell that confines the bubble. This includes the first detection of quiescent CO at negative LSR velocities in Orion. Given the harsh UV irradiation conditions in this translucent material, the detection of CO globules is surprising. These globules are small: R_cl=7,100 AU, not massive: M_cl=0.3 M_sun, and moderately dense: n_H=4x10^4 cm^-3 (median values). They are confined by the shell's external pressure, P_ext/k ~ 10^7 cm^-3 K, and are likely magnetically supported. They are either transient objects formed by instabilities or have detached from pre-existing molecular structures, sculpted by the passing shock associated with the expanding shell and by UV radiation from the Trapezium. Some represent the first stages in the formation of small pillars, others of isolated small globules. Although their masses do not suggest they will form stars, one globule matches the position of a known young stellar object. The lack of extended CO in the "Veil shell" demonstrates that feedback from massive stars expels, agitates, and reprocesses most of the disrupted molecular cloud gas; thus, limiting the star-formation rate in the region. The presence of globules is a result of this feedback.

[62]  arXiv:2004.12946 [pdf, ps, other]

Title: The evolution of the broadband temporal features observed in the black-hole transient MAXI J1820+070 with Insight-HXMT

Authors: Yanan Wang, Long Ji, S. N. Zhang, Mariano Méndez, J. L. Qu, Pierre Maggi, M. Y. Ge, Erlin Qiao, L. Tao, S. Zhang, Diego Altamirano, L. Zhang, X. Ma, F. J. Lu, T. P. Li, Y. Huang, S. J. Zheng, Y. P. Chen, Z. Chang, Y. L. Tuo, C. Gungor, L. M. Song, Y. P. Xu, X. L. Cao, Y. Chen, C. Z. Liu, Q. C. Bu, C. Cai, G. Chen, L. Chen, T. X. Chen, Y. B. Chen, W. Cui, W. W. Cui, J. K. Deng, Y. W. Dong, Y. Y. Du, M. X. Fu, G. H. Gao, H. Gao, M. Gao, Y. D. Gu, J. Guan, C. C. Guo, D. W. Han, J. Huo, S. M. Jia, L. H. Jiang, W. C. Jiang, J. Jin, Y. J. Jin, L. D. Kong, B. Li, C. K. Li, G. Li, M. S. Li, W. Li, X. Li, X. B. Li, X. F. Li, Y. G. Li, Z. W. Li, X. H. Liang, J. Y. Liao, G. Q. Liu, H. W. Liu, X. J. Liu, Y. N. Liu, B. Lu, X. F. Lu, Q. Luo, T. Luo, B. Meng, Y. Nang, J. Y. Nie, G. Ou, N. Sai, R. C. Shang, et al. (43 additional authors not shown)

Comments: Accepted for publication in ApJ

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

We study the evolution of the temporal properties of MAXI 1820+070 during the 2018 outburst in its hard state from MJD 58190 to 58289 with Insight-HXMT in a broad energy band 1-150 keV. We find different behaviors of the hardness ratio, the fractional rms and time lag before and after MJD 58257, suggesting a transition occurred at around this point. The observed time lags between the soft photons in the 1-5 keV band and the hard photons in higher energy bands, up to 150 keV, are frequency-dependent: the time lags in the low-frequency range, 2-10 mHz, are both soft and hard lags with a timescale of dozens of seconds but without a clear trend along the outburst; the time lags in the high-frequency range, 1-10 Hz, are only hard lags with a timescale of tens of milliseconds; first increase until around MJD 58257 and decrease after this date. The high-frequency time lags are significantly correlated to the photon index derived from the fit to the quasi-simultaneous NICER spectrum in the 1-10 keV band. This result is qualitatively consistent with a model in which the high-frequency time lags are produced by Comptonization in a jet.

[63]  arXiv:2004.12955 [pdf, ps, other]

Title: The evolutionary status of chemically peculiar eclipsing binary star DV Boo

Authors: Filiz Kahraman Alicavus, Fahri Alicavus

Comments: accepted for publication in RAA

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

Eclipsing binary systems are unique stellar objects to examine and understand the stellar evolution and the formation. Thanks to these systems, the fundamental stellar parameters (mass, radius) can be obtained very precisely. The existence of metallic-line (Am) stars in binaries is noticeably common. However, the known number of Am stars in eclipsing binaries is less. The Am stars in eclipsing binaries are extremely useful to deeply investigate the properties of Am stars, as the eclipsing binaries are the only tool to directly derive the fundamental stellar parameters. Additionally, the atmospheric parameters and the metallicities of the binary components could be obtained by a detailed spectroscopic study. Therefore, in this study, we present a comprehensive photometric and spectroscopic analysis of the eclipsing binary system DV\,Boo which has a possible Am component. The fundamental stellar parameters were determined by the analysis of radial velocity and photometric light curves. The atmospheric parameters of both binary components of DV\,Boo were derived using the disentangled spectra. The chemical abundance analysis was carried out as well. As a result, we showed that the primary component illustrates a typical Am star chemical abundance distribution. The fundamental stellar parameters of the binary components were also obtained with an accuracy of <1\% for masses and $<$3\% for radii. The evolutionary status of DV\,Boo was examined using the precisely obtained stellar parameters. The age of the system was found to be 1.00 +- 0.08\,Gyr.

[64]  arXiv:2004.12981 [pdf, other]

Title: On the importance of lensing for galaxy clustering in photometric and spectroscopic surveys

Authors: Goran Jelic-Cizmek, Francesca Lepori, Camille Bonvin, Ruth Durrer

Comments: 39 pages, 19 figures

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

We study the importance of gravitational lensing in the modelling of the number counts of galaxies. We confirm previous results for photometric surveys, showing that lensing cannot be neglected in a survey like LSST since it would infer a significant shift of cosmological parameters. For a spectroscopic survey like SKA2, we find that neglecting lensing in the monopole, quadrupole and hexadecapole of the correlation function also induces an important shift of parameters. For $\Lambda$CDM parameters, the shift is moderate, of the order of $0.6\sigma$ or less. However, for a model-independent analysis, that measures the growth rate of structure in each redshift bin, neglecting lensing introduces a shift of up to $2.3\sigma$ at high redshift. Since the growth rate is directly used to test the theory of gravity, such a strong shift would wrongly be interpreted as the breakdown of General Relativity. This shows the importance of including lensing in the analysis of future surveys. On the other hand, for a survey like DESI, we find that lensing is not important, mainly due to the value of the magnification bias parameter of DESI, $s(z)$, which strongly reduces the lensing contribution at high redshift. We also propose a way of improving the analysis of spectroscopic surveys, by including the cross-correlations between different redshift bins (which is neglected in spectroscopic surveys) from the spectroscopic survey or from a different photometric sample. We show that including the cross-correlations in the SKA2 analysis does not improve the constraints. On the other hand replacing the cross-correlations from SKA2 by cross-correlations measured with LSST improves the constraints by 10 to 20 %. Interestingly, for $\Lambda$CDM parameters, we find that LSST and SKA2 are highly complementary, since they are affected differently by degeneracies between parameters.

[65]  arXiv:2004.12985 [pdf]

Title: El Bahr: A Prospective Impact Crater

Authors: Antonia Paris, Shalabiea Osama M, Ahmed Mohamed, Evan Davies

Comments: 7 Pages, 8 Figures, Peer-reviewed and published

Journal-ref: Journal of the Washington Academy of Sciences, 2018

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

This preliminary investigation addresses the discovery of an unidentified crater located south of the Sahara Desert between Qaret Had El Bahr and Qaret El Allafa, Egypt. The unidentified crater (hereafter tentatively named El Bahr Crater) was discovered during a terrain analysis of the Sahara Desert. El Bahr Crater is located Southwest Al-Jiza Giza and is approximately 327 meters across, has a rim with a circumference of approximately 1,027 meters, and occupies a surface area of approximately 83,981 square meters. Preliminary spectral and topographic analysis reveal features characteristic of an impact crater produced by a hypervelocity event of extraterrestrial origin, including a bowl-shaped rim and a crater wall. No proximal and/or distal ejecta, however, are visible from Landsat imagery. Moreover, the geomorphic features, along with the fact that the El Bahr basalts are known to be rich in orthopyroxene while the surrounding basalts are not, imply an impact as the most plausible explanation. The El Bahr Crater is not indexed in the Earth Impact Database, and an analysis of impact structures in Africa did not identify it as either a confirmed, proposed or disproved impact crater. In collaboration with the University of Cairo, therefore, an expedition has been organized to conduct an in-situ investigation of El Bahr Crater, to ascertain if planar formations, shatter cones, and shock metamorphic and or other meteoritic properties are present.

[66]  arXiv:2004.12996 [pdf, other]

Title: Col-OSSOS: Compositional homogeneity of three Kuiper belt binaries

Authors: Michael Marsset, Wesley C. Fraser, Michele T. Bannister, Megan E. Schwamb, Rosemary E. Pike, Susan Benecchi, J. J. Kavelaars, Mike Alexandersen, Ying-Tung Chen, Brett J. Gladman, Stephen D. J. Gwyn, Jean-Marc Petit, Kathryn Volk

Comments: 10 pages, 4 figures, accepted to The Planetary Science Journal

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

The surface characterization of Trans-Neptunian Binaries (TNBs) is key to understanding the properties of the disk of planetesimals from which these objects formed. In the optical wavelengths, it has been demonstrated that most equal-sized component systems share similar colors, suggesting they have a similar composition. The color homogeneity of binary pairs contrasts with the overall diversity of colors in the Kuiper belt, which was interpreted as evidence that Trans-Neptunian Objects (TNOs) formed from a locally homogeneous and globally heterogeneous protoplanetary disk. In this paradigm, binary pairs must have formed early, before the dynamically hot TNOs were scattered out from their formation location. The latter inferences, however, relied on the assumption that the matching colors of the binary components imply matching composition. Here, we test this assumption by examining the component-resolved photometry of three TNBs found in the Outer Solar System Origins Survey: 505447 (2013 SQ99), 511551 (2014 UD225) and 506121 (2016 BP81), across the visible and J-band near-infrared wavelength range. We report similar colors within 2 sigma for the binary pairs suggestive of similar reflectance spectra and hence surface composition. This advocates for gravitational collapse of pebble clouds as a possible TNO formation route. We however stress that several similarly small TNOs, including at least one binary, have been shown to exhibit substantial spectral variability in the near-infrared, implying color equality of binary pairs is likely to be violated in some cases.

[67]  arXiv:2004.12999 [pdf, other]

Title: Constraining the delay time distribution of compact binary objects from the stochastic gravitational wave background searches

Authors: Mohammadtaher Safarzadeh, Sylvia Biscoveanu, Abraham Loeb

Comments: submitted to AAS journal, Comments are welcome

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

The initial separation of massive star binaries sets the timescale over which their compact remnants merge through the emission of gravitational waves. We show that the delay time distribution (DTD) of binary neutron stars or black holes can be inferred from the stochastic gravitational wave background (SGWB). If the DTD of a population is long, most of the mergers take place at low redshifts and the background would be rather quiet compared to a scenario in which the DTD is short leading to few individual detections at low redshift but a rather loud background. We show that different DTDs predict a factor of 5 difference in the magnitude of the gravitational wave background energy density ($\Omega_{\rm GW}$) and have the dominant effect on $\Omega_{\rm GW}$ over other factors such as the mass function of the primary BH mass, $p(m_1)$, the maximum considered BH mass ($M_{\rm max}$), and the effective spin of the black hole ($\chi_{\rm eff}$). A non-detection of such a background can rule out the short DTD scenario. We show that SGWB searches can rule out the short DTD scenario for the BBHs within about four years of observing time at advanced LIGO design sensitivty for a local merger rate of 30 $\rm Gpc^{-3} yr^{-1}$ assuming $p(m_1)\propto m_1^{-1}$, and $M_{\rm max}=50 M_{\odot}$.

Cross-lists for Tue, 28 Apr 20

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

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

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

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

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

[69]  arXiv:2004.12060 (cross-list from gr-qc) [pdf, other]

Title: Constraining $f(T,B)$ teleparallel gravity from energy conditions

Authors: Snehasish Bhattacharjee

Comments: 11 pages with 6 figures

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

$f(T,B)$ teleparallel gravity is a recently proposed straightforward generalization of the popular $f(T)$ teleparallel gravity by the incorporation of a boundary term $B=\frac{2}{e}\partial_{i}(e T ^{i}) = \bigtriangledown_{i}T^{i}$ where $T$ denote the torsion scalar \cite{ftb13}. In this work, I investigate the viability of some well motivated $f(T,B)$ teleparallel gravity models of the forms $f=\alpha B^n+\beta T^m$, $f=\alpha B^n T^m$ and $f=\alpha \log (B)+\beta T$ where $\alpha, \beta, n$ and $m$ are free parameters from the inequalities imposed the the weak energy condition. I use the recent estimates of Hubble, deceleration, jerk and snap parameters in finding corners in parameter spaces for the cosmological models for which the energy density remain positive and the weak energy condition ( i.e, $\rho+p \geq 0$, where $p$ and $\rho$ represent respectively the cosmological pressure and energy density) attains a minute positive value, as this implies the EoS parameter $\omega = p/\rho \simeq-1$ and therefore consistent with an accelerating universe.

[70]  arXiv:2004.12189 (cross-list from hep-ph) [pdf, ps, other]

Title: Supernova neutrino scattering off Gadolinium odd isotopes in water Cherenkov detectors

Authors: Paraskevi C. Divari

Comments: 10 pages, 5 figures, 2 Tables

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

In this work, the supernova neutrino(SN) charged-current interactions with Gd odd isotopes (A=155 and 157) are studied. We use measured spectra and the quasiparticle-phonon model (MQPM) to calculate the charged current response of odd Gd isotopes to supernova neutrinos. Flux-averaged cross-sections are obtained considering quasi-thermal neutrino spectra.

[71]  arXiv:2004.12270 (cross-list from physics.space-ph) [pdf, other]

Title: Development of a High Fidelity Simulator for Generalised Photometric Based Space Object Classification using Machine Learning

Authors: James Allworth, Lloyd Windrim, Jeffrey Wardman, Daniel Kucharski, James Bennett, Mitch Bryson

Comments: This paper is a pre-print that appeared in Proceedings of 70th International Astronautical Congress (IAC), 2019

Journal-ref: Proceedings of the 70th International Astronautical Congress, 2019

Subjects: Space Physics (physics.space-ph); Instrumentation and Methods for Astrophysics (astro-ph.IM); Computer Vision and Pattern Recognition (cs.CV)

This paper presents the initial stages in the development of a deep learning classifier for generalised Resident Space Object (RSO) characterisation that combines high-fidelity simulated light curves with transfer learning to improve the performance of object characterisation models that are trained on real data. The classification and characterisation of RSOs is a significant goal in Space Situational Awareness (SSA) in order to improve the accuracy of orbital predictions. The specific focus of this paper is the development of a high-fidelity simulation environment for generating realistic light curves. The simulator takes in a textured geometric model of an RSO as well as the objects ephemeris and uses Blender to generate photo-realistic images of the RSO that are then processed to extract the light curve. Simulated light curves have been compared with real light curves extracted from telescope imagery to provide validation for the simulation environment. Future work will involve further validation and the use of the simulator to generate a dataset of realistic light curves for the purpose of training neural networks.

[72]  arXiv:2004.12272 (cross-list from hep-ph) [pdf]

Title: Mass distribution of magnetized quark-nugget dark matter and comparison with observations

Authors: J. Pace VanDevender (VanDevender Enterprises LLC), Ian Shoemaker (Virginia Tech), T. Sloan (Lancaster University, UK), Aaron P. VanDevender (Founders Fund), Benjamin A. Ulmen (Sandia National Laboratories)

Comments: 24 pages including 2 page supplement, 6 figures, 1 table, 51 references

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

Quark nuggets are theoretical objects composed of approximately equal numbers of up, down, and strange quarks. They are also called strangelets, nuclearites, AQNs, slets, Macros, and MQNs. Quark nuggets are a candidate for dark matter, which has been a mystery for decades despite constituting ${\sim}85\%$ of the mass in the universe. Most previous models of quark nuggets have assumed no intrinsic magnetic field. However, Tatsumi found that quark nuggets may exist in magnetars as a ferromagnetic liquid with core magnetic field B between $10^{ 11}$ T and $10^{ 13}$ T. We apply that result to quark-nugget dark-matter and report results on aggregation of magnetized quark nuggets (MQNs) after formation from the quark-gluon plasma until expansion of the universe freezes out the mass distribution of $10^{ -24}$ kg to $10^{ 14}$ kg. Aggregation overcomes decay by weak interaction. Their aggregated mass distributions make MQNs consistent with all requirements for dark matter and fully compliant with Standard Model of Particle Physics. Observations narrow the range of B to between $10^{ 11}$ T and 3 $10^{ 13}$ T and indicate that geologic (craters in peat bogs) and planetary (seismic and radio-frequency emissions during passage through atmosphere) detectors can detect MQN dark matter.

[73]  arXiv:2004.12310 (cross-list from physics.comp-ph) [pdf, other]

Title: Time-implicit schemes in fluid dynamics? -- Their advantage in the regime of ultra-relativistic shock fronts

Authors: Moritz S. Fischer, Ahmad A. Hujeirat

Subjects: Computational Physics (physics.comp-ph); High Energy Astrophysical Phenomena (astro-ph.HE)

Relativistic jets are intrinsic phenomena of active galactic nuclei (AGN) and quasars. They have been observed to also emanate from systems containing compact objects, such as white dwarfs, neutron stars and black hole candidates. The corresponding Lorentz factors, $\Gamma$, were found to correlate with the compactness of the central objects. In the case of quasars and AGNs, plasmas with $\Gamma$-factors larger than $8$ were detected. However, numerically consistent modelling of propagating shock-fronts with $\Gamma \geq 4$ is a difficult issue, as the non-linearities underlying the transport operators increase dramatically with $\Gamma$, thereby giving rise to a numerical stagnation of the time-advancement procedure or alternatively they may diverge completely. In this paper, we present a unified numerical solver for modelling the propagation of one-dimensional shock fronts with high Lorentz factors. The numerical scheme is based on the finite-volume formulation with adaptive mesh refinement (AMR) and domain decomposition for parallel computation. It unifies both time-explicit and time-implicit numerical schemes within the framework of the pre-conditioned defect-correction iteration solution procedure. We find that time-implicit solution procedures are remarkably superior over their time-explicit counterparts in the very high $\Gamma$-regime and therefore most suitable for consistent modelling of relativistic outflows in AGNs and micro-quasars.

[74]  arXiv:2004.12326 (cross-list from hep-ph) [pdf, other]

Title: Clocking Out Superradiance Limits

Authors: Anubhav Mathur, Surjeet Rajendran, Erwin H. Tanin

Comments: 12 pages, 1 figure

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

The superradiant instability of black hole space-times has been used to place limits on ultra-light bosonic particles. We show that these limits are model dependent. While the initial growth of the mode is gravitational and thus model independent, the ability to place a limit on new particles requires the mode to grow unhindered to a large number density. Non-linear interactions between the particle and other light degrees of freedom that are mediated through higher dimension operators can damp this growth, eliminating the limit. However, these non-linearities may also destroy a cosmic abundance of these light particles, an attractive avenue for their discovery in several experiments. We study the specific example of the QCD axion and show that it is easy to construct models where these non-linearities eliminate limits from superradiance while preserving their cosmic abundance.

[75]  arXiv:2004.12328 (cross-list from physics.space-ph) [pdf, ps, other]

Title: Hyperfine excitation of SH$^+$ by H

Authors: François Lique, Alexandre Zanchet, Niyazi Bulut, Javier R. Goicoechea, Octavio Roncero

Comments: 3 figures

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

SH$^+$ is a surprisingly widespread molecular ion in diffuse interstellar clouds. There, it plays an important role triggering the sulfur chemistry. In addition, SH$^+$ emission lines have been detected at the UV-illuminated edges of dense molecular clouds, \mbox{so-called} photo-dissociation regions (PDRs), and toward high-mass protostars. An accurate determination of the SH$^+$ abundance and of the physical conditions prevailing in these energetic environments relies on knowing the rate coefficients of inelastic collisions between SH$^+$ molecules and hydrogen atoms, hydrogen molecules, and electrons. In this paper, we derive SH$^+$--H fine and hyperfine-resolved rate coefficients from the recent quantum calculations for the SH$^+$--H collisions, including inelastic, exchange and reactive processes. The method used is based on the infinite order sudden approach. State-to-state rate coefficients between the first 31 fine levels and 61 hyperfine levels of SH$^+$ were obtained for temperatures ranging from 10 to 1000 K. Fine structure-resolved rate coefficients present a strong propensity rule in favour of $\Delta j = \Delta N$ transitions. The $\Delta j = \Delta F$ propensity rule is observed for the hyperfine transitions. {The new rate coefficients will help significantly in the interpretation of SH$^+$ spectra from PDRs and UV-irradiated shocks where the abundance of hydrogen atoms with respect to hydrogen molecules can be significant.

[76]  arXiv:2004.12382 (cross-list from gr-qc) [pdf, ps, other]

Title: General constraints on Horndeski wormhole throats

Authors: Roman Korolev, Francisco S. N. Lobo, Sergey V. Sushkov

Comments: 16 pages

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

In this work, we consider the full Horndeski Lagrangian applied to wormhole geometries and present the full gravitational field equations. We analyse the general constraints imposed by the flaring-out conditions at the wormhole throat and consider a plethora of specific subclasses of the Horndeski Lagrangian, namely, quintessence/phantom fields, $k$-essence, scalar-tensor theories, covariant galileons, nonminimal kinetic coupling, kinetic gravity braiding, and the scalar-tensor representation of Gauss-Bonnet couplings, amongst others. The generic constraints analysed in this work serve as a consistency check of the main solutions obtained in the literature and draws out new avenues of research in considering applications of specific subclasses of the Horndeski theory to wormhole physics.

[77]  arXiv:2004.12448 (cross-list from physics.ed-ph) [pdf]

Title: Authentic Science Experiences with STEM Datasets: Post-secondary Results and Potential Gender Influences

Authors: Andria C. Schwortz, Andrea C. Burrows

Comments: Accepted to Research in Science & Technological Education; 40 pages, 12 tables

Subjects: Physics Education (physics.ed-ph); Astrophysics of Galaxies (astro-ph.GA)

Background: Dataset skills are used in STEM fields from healthcare work to astronomy research. Few fields explicitly teach students the skills to analyze datasets, and yet the increasing push for authentic science implies these skills should be taught.
Purpose: The overarching motivation is to understand learning of dataset skills within an astronomy context. Specifically, when participants work with a 200-entry Google Sheets dataset of astronomical data about quasars, what are they learning, how are they learning it, and who is doing the learning?
Sample: The authors studied a matched set of participants (n=87) consisting of 54 university undergraduate students (34 male, 18 female), and 33 science educators (16 male, 17 female).
Design and methods: Participants explored a three-phase dataset activity and were given an eight-question multiple-choice pre/post-test covering skills of analyzing datasets and astronomy content, with questions spanning Bloom's Taxonomy. Pre/post-test scores were compared and a t-test performed for subsamples by population.
Results: Participants exhibited learning of both dataset skills and astronomy content, indicating that dataset skills can be learned through this astronomy activity. Participants exhibited gains in both recall and synthesis questions, indicating learning is non-sequential. Female undergraduate students exhibited lower levels of learning than other populations.
Conclusions: Implications of the study include a stronger dataset focus in post-secondary STEM education and among science educators, and the need for further investigation into how instructors can ameliorate the challenges faced by female undergraduate students.

[78]  arXiv:2004.12549 (cross-list from gr-qc) [pdf, ps, other]

Title: A theory of type-II minimally modified gravity

Authors: Antonio De Felice, Andreas Doll, Shinji Mukohyama

Comments: 14 pages

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

We propose a modified gravity theory that propagates only two local gravitational degrees of freedom and that does not have an Einstein frame. According to the classification in JCAP 01 (2019) 017 [arXiv:1810.01047 [gr-qc]], this is a type-II minimally modified gravity theory. The theory is characterized by the gravitational constant $G_{\rm N}$ and a function $V(\phi)$ of a non-dynamical auxiliary field $\phi$ that plays the role of dark energy. Once one fixes a homogeneous and isotropic cosmological background, the form of $V(\phi)$ is determined and the theory no longer possesses a free parameter or a free function, besides $G_{\rm N}$. For $V'(\phi) = 0$ the theory reduces to general relativity (GR) with $G_N$ being the Newton's constant and $V=const.$ being the cosmological constant. For $V'(\phi) \ne 0$, it is shown that gravity behaves differently from GR but that GR with $G_{\rm N}$ being the Newton's constant is recovered for weak gravity at distance and time scales sufficiently shorter than the scale associated with $V(\phi)$. Therefore this theory provides the simplest framework of cosmology in which deviations from GR can be tested by observational data.

[79]  arXiv:2004.12664 (cross-list from gr-qc) [pdf, ps, other]

Title: First-principles study of Schwinger production of scalar particles during inflation and preheating

Authors: O.O. Sobol, E.V. Gorbar, A.I. Momot, S.I. Vilchinskii

Comments: 22 pages, 4 figures

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

By using the first-principles approach, we derive a system of three quantum kinetic equations governing the production and evolution of charged scalar particles by electric field in expanding Universe. Analyzing the ultraviolet asymptotic behavior of the kinetic functions, divergent parts of the electric current and the energy-momentum tensor of produced particles are found and the corresponding counterterms are determined. The renormalized system of equations is used to study the generation of electromagnetic fields during inflation and preheating in the kinetic coupling model $\mathcal{L}_{\rm EM}=-(1/4)f^{2}(\phi)F_{\mu\nu}F^{\mu\nu}$ with the Ratra coupling function $f=\exp(\beta\phi/M_{p})$. It is found that the electric current of created particles is retarded with respect to the electric field. This leads to an oscillatory behavior of both quantities in agreement with the results obtained previously in phenomenological kinetic and hydrodynamical approaches.

[80]  arXiv:2004.12766 (cross-list from physics.data-an) [pdf, ps, other]

Title: Parametric unfolding. Method and restrictions

Authors: Nikolay Gagunashvili

Comments: 14 pages, 9 figures

Subjects: Data Analysis, Statistics and Probability (physics.data-an); Instrumentation and Methods for Astrophysics (astro-ph.IM); High Energy Physics - Experiment (hep-ex); Nuclear Experiment (nucl-ex); Applications (stat.AP)

Parametric unfolding of a true distribution distorted due to finite resolution and limited efficiency for the registration of individual events is discussed. Details of the computational algorithm of the unfolding procedure are presented.

[81]  arXiv:2004.12874 (cross-list from gr-qc) [pdf, ps, other]

Title: Extremal Kerr white holes as a source of ultra high energy particles

Authors: Mandar Patil, Tomohiro Harada

Comments: 21 pages, 4 figures

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

We consider a process where two identical massive particles fall inwards, starting from rest at infinity towards the extremal Kerr black hole, collide outside the event horizon in its vicinity and produce two massless particles. The center of mass energy of collision between the two particles diverges if one of the particle admits a specific critical value of the angular momentum and if the collision takes place at a location arbitrarily close to the event horizon. Assuming the isotropic emission of particles in the center of mass frame we show that one of the massless particles produced has divergent conserved energy comparable to the center of mass energy with probability slightly less than half. This particle enters the black hole event horizon which coincides with the Cauchy horizon, turns back, and emerges through the white hole event horizon into another asymptotic region in the maximal extension of Kerr spacetime. Since conserved energy is preserved in this process, it is perceived as a particle with divergent energy by the observer when it reaches infinity. Thus the extremal white hole appears to be a source of ultra high energy particles. Similar processes wherein collision takes place slightly inside the black hole event horizon or just outside or inside of white hole event horizon also produce high energy particles.

Replacements for Tue, 28 Apr 20

[82]  arXiv:1801.05942 (replaced) [pdf, other]

Title: Imprints of the redshift evolution of double neutron star merger rate on the signal to noise ratio distribution

Authors: Shilpa Kastha, M. Saleem, K G Arun

Comments: 9 pages, 4 figures

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

[83]  arXiv:1801.06859 (replaced) [pdf, other]

Title: Magnetic Imprisonment of Dusty Pinballs by a Supernova Remnant

Authors: Brian J. Fry, Brian D. Fields, John R. Ellis

Comments: 31 pages, 13 figures. Comments welcome

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

[84]  arXiv:1812.05216 (replaced) [pdf, other]

Title: On the slow quenching of M* galaxies: heavily-obscured AGNs clarify the picture

Authors: Thibaud Moutard, Nicola Malavasi, Marcin Sawicki, Stéphane Arnouts, Shruti Tripathi

Comments: 11 pages, 6 figures; submitted to MNRAS; latest revised version

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

[85]  arXiv:1901.02724 (replaced) [pdf, other]

Title: Can HI gas trace the matter density distribution linearly on large scales?

Authors: Zhenyuan Wang (Tsinghua/PSU), Yangyao Chen (Tsinghua), Yi Mao (Tsinghua), Houjun Mo (Tsinghua/UMass), Huiyuan Wang (USTC), Hong Guo (SHAO), Cheng Li (Tsinghua), Jian Fu (SHAO), Yipeng Jing (SJTU), Jing Wang (PKU), Xiaohu Yang (SJTU), Zheng Zheng (Utah)

Comments: 8 pages, 5 figures

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

[86]  arXiv:1902.04877 (replaced) [pdf, other]

Title: Estimating the Integrated Bispectrum from Weak Lensing Maps

Authors: D. Munshi, J. D. McEwen, T. Kitching, P. Fosalba, R. Teyssier, J. Stadel

Comments: 49 pages, 8 figures, To appear in JCAP

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

[87]  arXiv:1903.10698 (replaced) [pdf, other]

Title: A Galactic centre gravitational-wave Messenger

Authors: Marek Abramowicz, Michal Bejger, Eric Gourgoulhon, Odele Straub

Comments: 7 pages, 2 figures, published in Scientific Reports

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

[88]  arXiv:1905.03792 (replaced) [pdf, other]

Title: Precise predictions for multi-${\rm TeV}$ and ${\rm PeV}$ energy neutrino scattering rates

Authors: Rhorry Gauld

Comments: 7 pages, 5 figures. v2: Matches published version. Additionally includes coherent scattering results. All numerical results available from zeondo record: this https URL

Journal-ref: Phys. Rev. D 100, 091301 (2019)

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

[89]  arXiv:1906.07676 (replaced) [pdf, other]

Title: Euclid: Nonparametric point spread function field recovery through interpolation on a graph Laplacian

Authors: M. A. Schmitz, J.-L. Starck, F. Ngole Mboula, N. Auricchio, J. Brinchmann, R. I. Vito Capobianco, R. Clédassou, L. Conversi, L. Corcione, N. Fourmanoit, M. Frailis, B. Garilli, F. Hormuth, D. Hu, H. Israel, S. Kermiche, T. D. Kitching, B. Kubik, M. Kunz, S. Ligori, P. B. Lilje, I. Lloro, O. Mansutti, O. Marggraf, R. J. Massey, F. Pasian, V. Pettorino, F. Raison, J. D. Rhodes, M. Roncarelli, R. P. Saglia, P. Schneider, S. Serrano, A. N. Taylor, R. Toledo-Moreo, L. Valenziano, C. Vuerli, J. Zoubian

Comments: 19 pages, 19 figures. This version matches that published in A&A

Journal-ref: A&A 636, A78 (2020)

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

[90]  arXiv:1906.09980 (replaced) [pdf, ps, other]

Title: New Type Ia supernova Yields and the Manganese and Nickel Problems in the Milky Way and Dwarf Spheroidal Galaxies

Authors: Chiaki Kobayashi, Shing-Chi Leung, Ken'ichi Nomoto

Comments: 23 pages, 26 figures, Accepted for publication in the Astrophysical Journal

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

[91]  arXiv:1906.10825 (replaced) [pdf, other]

Title: A new cosmological probe using super-massive black hole shadows

Authors: Jing-Zhao Qi, Xin Zhang

Comments: 5 pages, 3 figures

Journal-ref: Chinese Physics C Vol. 44, No. 5 (2020) 055101

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

[92]  arXiv:1908.00987 (replaced) [pdf, other]

Title: Electromagnetic transients and gravitational waves from white dwarf disruptions by stellar black holes in triple systems

Authors: Giacomo Fragione, Brian D. Metzger, Rosalba Perna, Nathan W. C. Leigh, Bence Kocsis

Comments: 13 pages, 8 figures, 1 table, accepted by MNRAS

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

[93]  arXiv:1908.04589 (replaced) [pdf, other]

Title: Study of Particle Multiplicity of Cosmic Ray Events using 2m$\times$2m Resistive Plate Chamber Stack at IICHEP-Madurai

Authors: Suryanarayan Mondal, V. M. Datar, Gobinda Majumder, N. K. Mondal, S. Pethuraj, K. C. Ravindran, B. Satyanarayana

Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Experiment (hep-ex); Instrumentation and Detectors (physics.ins-det)

[94]  arXiv:1908.09841 (replaced) [pdf, other]

Title: Dark Matter and Naturalness

Authors: Mark P. Hertzberg, McCullen Sandora

Comments: 32 pages, 3 figures. V2: Further clarifications; updated towards version published in JHEP

Journal-ref: JHEP 12 (2019) 037

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

[95]  arXiv:1909.11873 (replaced) [pdf, other]

Title: Massively parallel Bayesian inference for transient gravitational-wave astronomy

Authors: Rory Smith, Gregory Ashton, Avi Vajpeyi, Colm Talbot

Comments: 9 pages, 2 figures, 1 table

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

[96]  arXiv:1909.12889 (replaced) [pdf, other]

Title: Sandblasting the $\textit{r}$-Process: Spallation of Ejecta from Neutron Star Mergers

Authors: Xilu Wang, Brian D. Fields, Matthew Mumpower, Trevor Sprouse, Rebecca Surman, Nicole Vassh

Comments: 30 pages, 11 figures, 1 table, v2 matches version to appear in ApJ

Journal-ref: The Astrophysical Journal, 2020, Volume 893, Number 2

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

[97]  arXiv:1910.05015 (replaced) [pdf, other]

Title: A mean density of $112\, M_{\odot}\,\rm pc^{-3}$ for Central Molecular Zone clumps -- Evidences for shear-enabled pressure equilibrium in the Galactic Center

Authors: Guang-Xing Li, Chuan-Peng Zhang

Comments: Accepted for publication by the ApJ

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

[98]  arXiv:1910.08077 (replaced) [pdf, other]

Title: A Novel CMB Component Separation Method: Hierarchical Generalized Morphological Component Analysis

Authors: Sebastian Wagner-Carena, Max Hopkins, Ana Diaz Rivero, Cora Dvorkin

Comments: Updated to reflect accepted MNRAS version

Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Instrumentation and Methods for Astrophysics (astro-ph.IM); Machine Learning (cs.LG); Data Analysis, Statistics and Probability (physics.data-an)

[99]  arXiv:1910.08324 (replaced) [pdf, ps, other]

Title: Single Pulse Detection Algorithms for Real-time Fast Radio Burst Searches using GPUs

Authors: Karel Adamek, Wesley Armour

Comments: Published in The Astrophysical Journal Supplement Series

Journal-ref: The Astrophysical Journal Supplement Series 247, 56 (2020)

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

[100]  arXiv:1910.08558 (replaced) [pdf, other]

Title: CP violation and circular polarisation in neutrino radiative decay

Authors: Shyam Balaji, Maura Ramirez-Quezada, Ye-Ling Zhou

Comments: 25 pages, 3 figures, discussions added, published in JHEP

Journal-ref: JHEP 2004 (2020) 178

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

[101]  arXiv:1910.08559 (replaced) [pdf, ps, other]

Title: Extremely Metal-Poor Representatives Explored by the Subaru Survey (EMPRESS). I. A Successful Machine Learning Selection of Metal-Poor Galaxies and the Discovery of a Galaxy with M*<10^6 M_sun and 0.017 Z_sun

Authors: Takashi Kojima (1,2), Masami Ouchi (1,3,4), Michael Rauch (5), Yoshiaki Ono (1), Kimihiko Nakajima (4), Yuki Isobe (1,2), Seiji Fujimoto (6,7), Yuichi Harikane (4,8), Takuya Hashimoto (9), Masao Hayashi (4), Yutaka Komiyama (4), Haruka Kusakabe (10), Ji Hoon Kim (11,12), Chien-Hsiu Lee (13), Shiro Mukae (1,2), Tohru Nagao (14), Masato Onodera (8,15), Takatoshi Shibuya (16), Yuma Sugahara (17), Masayuki Umemura (18), Kiyoto Yabe (3) ((1) ICRR, (2) Univ. of Tokyo, (3) Kavli IPMU, (4) NAOJ, (5) Carnegie Observatory, (6) DAWN fellow, (7) Univ. of Copenhagen, (8) UCL, (9) TCHoU, (10) Observatoire de Geneve, (11) Subaru Telescope, (12) Metaspace, (13) NOAO, (14) Ehime Univ., (15) SOKENDAI, (16) Kitami Institute of Tech., (17) Waseda Univ., (18) Univ. of Tsukuba)

Comments: 30 pages, 26 figures, and 8 tables; (Revision: metallicities changed due to the use of a more pricise dust correction method, but conclusion does not change, Minor: a table, some figures, and sentences are added for a clear explanation.)

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

[102]  arXiv:1911.02021 (replaced) [pdf, other]

Title: Cosmic Ray Driven Outflows from the Large Magellanic Cloud: Contributions to the LMC Filament

Authors: Chad Bustard, Ellen G. Zweibel, Elena D'Onghia, J.S. Gallagher III, Ryan Farber

Comments: 23 pages, 13 figures, 2 tables. Accepted to ApJ. See expanded discussion of clustered stellar feedback in Section 3 and clarifications in Figure 3

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

[103]  arXiv:1911.05311 (replaced) [pdf, ps, other]

Title: Gravitational lensing signature of matter distribution around Schwarzschild black hole

Authors: Harsha Miriam Reji, Mandar Patil

Comments: 42 pages, 7 figures, published in PRD

Journal-ref: Phys. Rev. D 101, 064051 (2020)

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

[104]  arXiv:1911.11671 (replaced) [pdf, ps, other]

Title: Black Hole Ringdown as a Probe for Dark Energy

Authors: Johannes Noller, Luca Santoni, Enrico Trincherini, Leonardo G. Trombetta

Comments: 10+4 pages, 2 figures, 1 table

Journal-ref: Phys. Rev. D 101, 084049 (2020)

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

[105]  arXiv:1912.04916 (replaced) [pdf, other]

Title: Characterising the Dynamo in a Radiatively Inefficient Accretion Flow

Authors: Prasun Dhang, Abhijit Bendre, Prateek Sharma, Kandaswamy Subramanian

Comments: 13 pages, 11 figures, published in MNRAS

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

[106]  arXiv:1912.05398 (replaced) [pdf, ps, other]

Title: Low energy core collapse supernovae in the frame of the jittering jets explosion mechanism

Authors: Roni Anna Gofman, Noam Soker

Comments: New version after comments by the referee, Accepted for publication in MNRAS

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

[107]  arXiv:1912.08301 (replaced) [pdf, other]

Title: The PDFI_SS Electric Field Inversion Software

Authors: George H. Fisher, Maria D. Kazachenko, Brian T. Welsch, Xudong Sun, Erkka Lumme, David J. Bercik, Marc L. DeRosa, Mark C. M. Cheung

Comments: 68 pages, 28 figures, 3 tables. This version (arXiv) will be updated when major changes to the software occur

Journal-ref: Astrophysical Journal Supplement Series, 248:2 (52pp) 2020 May

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

[108]  arXiv:1912.12723 (replaced) [pdf, ps, other]

Title: Stabilizing effect of magnetic helicity on magnetic cavities in the intergalactic medium

Authors: Simon Candelaresi, Fabio Del Sordo

Comments: 9 pages, 9 figures. Accepted for publication in the Astrophysical Journal

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

[109]  arXiv:2001.02897 (replaced) [pdf, ps, other]

Title: Second law of black hole thermodynamics

Authors: Koji Azuma, Go Kato

Comments: 8 pages, 1 figure

Subjects: High Energy Physics - Theory (hep-th); High Energy Astrophysical Phenomena (astro-ph.HE); Statistical Mechanics (cond-mat.stat-mech); General Relativity and Quantum Cosmology (gr-qc); Quantum Physics (quant-ph)

[110]  arXiv:2001.06492 (replaced) [pdf, other]

Title: On the origin of GW190425

Authors: Isobel M Romero-Shaw, Nicholas Farrow, Simon Stevenson, Eric Thrane, Xing-Jiang Zhu

Comments: 5 pages, 3 figures

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

[111]  arXiv:2001.08340 (replaced) [pdf, other]

Title: The Radial Acceleration Relation in CLASH Galaxy Clusters

Authors: Yong Tian, Keiichi Umetsu, Chung-Ming Ko, Megan Donahue, I-Non Chiu

Comments: Version accepted by ApJ. Textual changes to improve clarity. Semi-analytical model predictions improved (Figures 3, 4, and 5), better agreement with data. Results and conclusions unchanged

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

[112]  arXiv:2001.11032 (replaced) [pdf, other]

Title: Universal transition diagram from dormant to actively accreting supermassive black holes

Authors: Kohei Inayoshi, Kohei Ichikawa, Luis C. Ho

Comments: 9 pages (main text), 2 figures, 1 table, accepted for publication in ApJ

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

[113]  arXiv:2002.07967 (replaced) [pdf, other]

Title: Effective field theory of degenerate higher-order inflation

Authors: Hayato Motohashi, Wayne Hu

Comments: 24 pages, 5 figures; matches published version

Journal-ref: Phys. Rev. D 101, 083531 (2020)

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

[114]  arXiv:2002.08883 (replaced) [pdf]

Title: Datasets of ionospheric parameters provided by SCINDA GNSS receiver from Lisbon airport area

Authors: Tatiana Barlyaeva, Teresa Barata, Anna Morozova

Comments: arXiv admin note: text overlap with arXiv:1910.04044

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

[115]  arXiv:2002.10471 (replaced) [pdf, other]

Title: Small-scale structure traced by neutral hydrogen absorption in the direction of multiple-component radio continuum sources

Authors: Daniel R. Rybarczyk, Snezana Stanimirovic, Ellen G. Zweibel, Claire E. Murray, John M. Dickey, Brian Babler, Carl Heiles

Comments: 29 pages, 19 figures, 4 tables. Accepted to ApJ. Section 4.3.1 updated from previous version

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

[116]  arXiv:2002.12152 (replaced) [pdf, ps, other]

Title: The persistent radio jet coupled to hard X-rays in the soft state of Cyg X-1

Authors: Andrzej A. Zdziarski, J. N. S. Shapopi, Guy G. Pooley

Comments: ApJL in press, 6 pages

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

[117]  arXiv:2003.02066 (replaced) [pdf, other]

Title: Bounce from Inflation

Authors: Debottam Nandi (IIT Madras, India)

Comments: 5 pages, 3 figures, references added with minor modifications

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

[118]  arXiv:2003.02069 (replaced) [pdf, ps, other]

Title: A surprise in the updated list of stellar perturbers of long period comets motion

Authors: Rita Wysoczańska, Piotr A. Dybczyński, Magdalena Polińska

Comments: 12 pages, 3 figures, submitted to Astronomy and Astrophysics

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

[119]  arXiv:2003.07431 (replaced) [pdf, ps, other]

Title: Inflationary equilibrium configurations of scalar-tensor theories of gravity

Authors: Israel Quiros, Tame Gonzalez, Roberto De Arcia, Ricardo García-Salcedo, Ulises Nucamendi, Joel F. Saavedra

Comments: 30 pages, 6 figures (12 eps files). Comments acknowledged. Version accepted in PRD

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

[120]  arXiv:2003.10460 (replaced) [pdf, ps, other]

Title: Proton Synchrotron $γ$-rays and the Energy Crisis in Blazars

Authors: I. Liodakis, M. Petropoulou

Comments: 8 pages, 4 figures, accepted for publication in the Astrophysical Journal Letters

Journal-ref: Volume 893, Issue 1, id.L20, April 2020

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

[121]  arXiv:2004.03941 (replaced) [pdf, other]

Title: Global Mapping of an Exo-Earth using Sparse Modeling

Authors: Masataka Aizawa, Hajime Kawahara, Siteng Fan

Comments: 17 pages, 9 figures; revised assumptions of distance to a planet and telescope size in section 5; accepted for publication in the Astrophysical Journal

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

[122]  arXiv:2004.04930 (replaced) [pdf, ps, other]

Title: Study of Recent outburst in the Be/X-ray binary RX J0209.6-7427 with AstroSat: A new ultraluminous X-ray pulsar in the Magellanic Bridge?

Authors: Amar Deo Chandra, Jayashree Roy, P. C. Agrawal, Manojendu Choudhury

Comments: 9 pages, 8 figures, accepted for publication in MNRAS Journal

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

[123]  arXiv:2004.06476 (replaced) [pdf, other]

Title: A search for new $γ$-ray blazars from infrared selected candidates

Authors: Blessing Musiimenta, Bruno Sversut Arsioli, Edward Jurua, Tom Mutabazi

Comments: 3 pages, 2 figures, Proceedings paper of the IAU symposium "Nuclear Activity in Galaxies Across Cosmic Time" (Ethiopia) accepted to be published under the Cambridge University Press, eds. M. Povi\'c, P. Marziani, J. Masegosa, H. Netzer, S. H. Negu, and S. B. Tessema, the first figure is made clear with energy and time ranges

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

[124]  arXiv:2004.06733 (replaced) [pdf, other]

Title: Modeling Dark Photon Oscillations in Our Inhomogeneous Universe

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

Comments: 22+4 pages, 17 figures; v2, clarified comparison with previous work, minor improvements to the text, results and conclusions unchanged

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

[125]  arXiv:2004.08342 (replaced) [pdf, other]

Title: GW190412: Observation of a Binary-Black-Hole Coalescence with Asymmetric Masses

Authors: The LIGO Scientific Collaboration, the Virgo Collaboration: R. Abbott, T. D. Abbott, S. Abraham, F. Acernese, K. Ackley, C. Adams, R. X. Adhikari, V. B. Adya, C. Affeldt, M. Agathos, K. Agatsuma, N. Aggarwal, O. D. Aguiar, A. Aich, L. Aiello, A. Ain, P. Ajith, S. Akcay, G. Allen, A. Allocca, P. A. Altin, A. Amato, S. Anand, A. Ananyeva, S. B. Anderson, W. G. Anderson, S. V. Angelova, S. Ansoldi, S. Antier, S. Appert, K. Arai, M. C. Araya, J. S. Areeda, M. Arène, N. Arnaud, S. M. Aronson, K. G. Arun, Y. Asali, S. Ascenzi, G. Ashton, S. M. Aston, P. Astone, F. Aubin, P. Aufmuth, K. AultONeal, C. Austin, V. Avendano, S. Babak, P. Bacon, F. Badaracco, M. K. M. Bader, S. Bae, A. M. Baer, J. Baird, F. Baldaccini, G. Ballardin, S. W. Ballmer, A. Bals, A. Balsamo, G. Baltus, S. Banagiri, D. Bankar, et al. (1192 additional authors not shown)

Comments: 26 pages, 11 figures; author list added

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

[126]  arXiv:2004.08536 (replaced) [pdf, other]

Title: The obscured X-ray binaries V404 Cyg, Cyg X-3, V4641 Sgr, and GRS 1915+105

Authors: Karri I. I. Koljonen, John A. Tomsick

Comments: 24 pages, 14 figures, 8 tables. Accepted for publication in A&A. Abstract slightly abridged to meet ArXiv size limit

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

[127]  arXiv:2004.09076 (replaced) [pdf, other]

Title: Warming Early Mars with Climate Cycling: The Effect of CO2-H2 Collision-induced Absorption

Authors: Benjamin P.C. Hayworth, Ravi Kumar Kopparapu, Jacob Haqq-Misra, Natasha E. Batalha, Rebecca C. Payne, Bradford J. Foley, Mma Ikwut-Ukwa, James F. Kasting

Comments: Publication date July 15 2020

Journal-ref: Icarus 345 (2020) 113770

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

[128]  arXiv:2004.09291 (replaced) [pdf, other]

Title: Investigating the relationship between cosmic curvature and dark energy models with the latest supernova sample

Authors: Chao Gao, Yun Chen, Jie Zheng

Comments: 8 pages, 2 figures, 1 table, accepted for publication in RAA

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

[129]  arXiv:2004.09586 (replaced) [pdf, other]

Title: Unusually High CO Abundance of the First Active Interstellar Comet

Authors: M. A. Cordiner, S. N. Milam, N. Biver, D. Bockelée-Morvan, N. X. Roth, E. A. Bergin, E. Jehin, A. J. Remijan, S. B. Charnley, M. J. Mumma, J. Boissier, J. Crovisier, L. Paganini, Y.-J. Kuan, D. C Lis

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

[130]  arXiv:2004.09979 (replaced) [pdf, other]

Title: Using quasar X-ray and UV flux measurements to constrain cosmological model parameters

Authors: Narayan Khadka, Bharat Ratra

Comments: 16 pages, 14 figures. arXiv admin note: text overlap with arXiv:1909.01400

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)

[131]  arXiv:2004.10817 (replaced) [pdf, other]

Title: A dark matter profile to model diverse feedback-induced core sizes of $Λ$CDM haloes

Authors: Alexandres Lazar, James S. Bullock, Michael Boylan-Kolchin, T.K. Chan, Philip F. Hopkins, Andrew S. Graus, Andrew Wetzel, Kareem El-Badry, Coral Wheeler, Maria C. Straight, Dušan Kereš, Claude-André Faucher-Giguère, Alex Fitts, Shea Garrison-Kimmel

Comments: Submitted to MNRAS; corrected typos

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

[132]  arXiv:2004.11223 (replaced) [pdf, ps, other]

Title: A Geometrical Explanation for Repeating Fast Radio Bursts

Authors: Shuang Du, Weihua Wang, Xuhao Wu, Renxin Xu

Comments: 5 pages, 2 figures

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

[133]  arXiv:2004.11225 (replaced) [pdf, other]

Title: Spectroscopic Orbits of Eleven Nearby, Mid-to-Late M Dwarf Binaries

Authors: Jennifer G. Winters (1), Jonathan M. Irwin (1), David Charbonneau (1), David W. Latham (1), Amber M. Medina (1), Jessica Mink (1), Gilbert A. Esquerdo (1), Perry Berlind (1), Michael L. Calkins (1), Zachory K. Berta-Thompson (2) ((1) Center for Astrophysics | Harvard & Smithsonian, (2) UC Boulder)

Comments: Accepted for publication in AJ. Full table of RVs available upon request before publication. Corrected uncertainty on LHS 1817 mass ratio & T_eff

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

[134]  arXiv:2004.11669 (replaced) [pdf, other]

Title: Why the mean mass of primordial black hole distribution is close to 10$M_{\odot}$

Authors: Alexander Dolgov (ITEP Moscow, NGU Novosibirsk), Konstantin Postnov (Sternberg Astronomical Institute, Moscow)

Comments: 4 pages, LaTeX, no figures; typos corrected

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

• New submissions
• Cross-lists
• Replacements