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New submissions for Thu, 21 Nov 19

[1]  arXiv:1911.08488 [pdf, other]

Title: The NANOGrav 11-Year Data Set: Limits on Gravitational Wave Memory

Authors: K. Aggarwal, Z. Arzoumanian, P. T. Baker, A. Brazier, P. R. Brook, S. Burke-Spolaor, S. Chatterjee, J. M. Cordes, N. J. Cornish, F. Crawford, H. T. Cromartie, K. Crowter, M. Decesar, P. B. Demorest, T. Dolch, J. A. Ellis, R. D. Ferdman, E. Ferrara, P. Gentile, D. Good, J. S. Hazboun, A. M. Holgado, E. A. Huerta, K. Islo, R. Jennings, G. Jones, M. L. Jones, D. L. Kaplan, L. Z. Kelley, J. S. Key, M. T. Lam, T. J. W. Lazio, L. Levin, D. R. Lorimer, J. Luo, R. S. Lynch, D. R. Madison, M. A. McLaughlin, S. T. McWilliams, C. M. F. Mingarelli, C. Ng, D. J. Nice, T. T. Pennucci, N. S. Pol, S. M. Ransom, P. S. Ray, X. Siemens, J. Simon, R. Spiewak, I. H. Stairs, D. R. Stinebring, K. Stovall, J. K. Swiggum, S. R. Taylor, M. Vallisneri, R. Van Haasterer, S. J. Vigeland, C. A. Witt, W. W. Zhu, (The NANOGrav Collaboration)

Comments: 10 pages, 6 figures, submitted to ApJ

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

The mergers of supermassive black hole binaries (SMBHB) promise to be incredible sources of gravitational waves (GW). While the oscillatory part of the merger gravitational waveform will be outside the frequency sensitivity range of pulsar timing arrays (PTA), the non-oscillatory GW memory effect is detectable. Further, any burst of gravitational waves will produce GW memory, making memory a useful probe of unmodeled exotic sources and new physics. We searched the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) 11-year data set for GW memory. Finding no evidence for GWs, we placed limits on the strain amplitude of GW memory events during the observation period. We then used the strain upper limits to place limits on the rate of GW memory causing events. At a strain of $2.5\times10^{-14}$, corresponding to the median upper limit as a function of source sky position, we set a limit on the rate of GW memory events at $<0.4$ yr$^{-1}$. That strain corresponds to a SMBHB merger with reduced mass of $\eta M \sim 2\times10^{10}M_\odot$ at a distance of 1 Gpc.
As a test of our analysis, we analyzed the NANOGrav 9-year data set as well. This analysis found an anomolous signal, which does not appear in the 11-year data set. This signal is not a GW, and its origin remains unknown.

[2]  arXiv:1911.08491 [pdf, ps, other]

Title: The Pristine survey X: a large population of low-metallicity stars permeates the Galactic disk

Authors: Federico Sestito, Nicolas F. Martin, Else Starkenburg, Anke Arentsen, Rodrigo A. Ibata, Nicolas Longeard, Collin Kielty, Kristopher Youakim, Kim A. Venn, David S. Aguado, Raymond G. Carlberg, Jonay I. Gonzalez Hernandez, Vanessa Hill, Pascale Jablonka, Georges Kordopatis, Khyati Malhan, Julio F. Navarro, Ruben Sanchez-Janssen, Guillame Thomas, Eline Tolstoy, Thomas G. Wilson, Pedro Alonso Palicio, Spencer Bialek, Rafael Garcia-Dias, Romain Lucchesi, Pierre North, Yeisson Osorio, Lee R. Patrick, Luis Peralta de Arriba

Comments: Submitted to MNRAS letter, 5 pages with 1 figure. Appendices A and B with 3 figures

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

The orbits of the least chemically enriched stars open a window on the formation of our Galaxy when it was still in its infancy. The common picture is that these low-metallicity stars are distributed as an isotropic, pressure-supported component since these stars were either accreted from the early building blocks of the assembling Milky Way, or were later brought by the accretion of faint dwarf galaxies. Combining the metallicities and radial velocities from the Pristine and LAMOST surveys and Gaia DR2 parallaxes and proper motions for an unprecedented large and unbiased sample of very metal-poor stars at $[Fe/H]\leq-2.5$ we show that this picture is incomplete. This sample shows strong statistical evidence (at the $5.0\sigma$ level) of asymmetry in their kinematics, favouring prograde motion. Moreover, we find that $31\%$ of the stars that currently reside in the disk do not venture outside of the disk plane throughout their orbit. The discovery of this population implies that a significant fraction of stars with iron abundances $[Fe/H]\leq-2.5$ formed within or concurrently with the Milky Way disk and that the history of the disk was quiet enough to allow them to retain their disk-like orbital properties.

[3]  arXiv:1911.08492 [pdf, ps, other]

Title: Pulsed Disc Accretion Driven by Hot Jupiters

Authors: Jean Teyssandier, Dong Lai

Comments: 10 pages, 12 figures, submitted to MNRAS

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

We present 2D hydrodynamical simulations of hot Jupiters orbiting near the inner edge of protoplanetary discs. We systemically explore how the accretion rate at the inner disc edge is regulated by a giant planet of different mass, orbital separation and eccentricity. We find that a massive (with planet-to-star mass ratio $\gtrsim 0.003$) eccentric ($e_p\gtrsim 0.1$) planet drives a pulsed accretion at the inner edge of the disc, modulated at one or two times the planet's orbital frequency. The amplitude of accretion variability generally increases with the planet mass and eccentricity, although some non-monotonic dependences are also possible. Applying our simulation results to the T Tauri system CI Tau, where a young hot Jupiter candidate has been detected, we show that the observed luminosity variability in this system can be explained by pulsed accretion driven by an eccentric giant planet.

[4]  arXiv:1911.08493 [pdf, other]

Title: Birds of a Feather? Magellan/IMACS Spectroscopy of the Ultra-Faint Satellites Grus II, Tucana IV, and Tucana V

Authors: J. D. Simon, T. S. Li, D. Erkal, A. B. Pace, A. Drlica-Wagner, D. J. James, J. L. Marshall, K. Bechtol, T. Hansen, K. Kuehn, C. Lidman, S. Allam, J. Annis, S. Avila, E. Bertin, D. Brooks, D. L. Burke, A. Carnero Rosell, M. Carrasco Kind, J. Carretero, L. N. da Costa, J. De Vicente, S. Desai, P. Doel, T. F. Eifler, S. Everett, P. Fosalba, J. Frieman, J. Garcia-Bellido, E. Gaztanaga, D. W. Gerdes, D. Gruen, R. A. Gruendl, J. Gschwend, G. Gutierrez, D. L. Hollowood, K. Honscheid, E. Krause, N. Kuropatkin, N. MacCrann, M. A. G. Maia, M. March, R. Miquel, A. Palmese, F. Paz-Chinchon, A. A. Plazas, K. Reil, A. Roodman, E. Sanchez, B. Santiago, V. Scarpine, M. Schubnell, S. Serrano, M. Smith, E. Suchyta, G. Tarle, A. R. Walker

Comments: 16 pages, 9 figures, 6 tables. Submitted for publication in the AAS Journals

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

We present Magellan/IMACS spectroscopy of three recently discovered ultra-faint Milky Way satellites, Grus II, Tucana IV, and Tucana V. We measure systemic velocities of V_hel = -110.0 +/- 0.5 km/s, V_hel = 15.9 +/- 1.8 km/s, and V_hel = -36.2 +/-2.5 km/s for the three objects, respectively. Their large relative velocity differences demonstrate that the satellites are unrelated despite their close physical proximity to one another. We determine a velocity dispersion for Tuc IV of sigma = 4.3^+1.7_-1.0 km/s, but are unable to resolve the velocity dispersions of the other two systems. For Gru II we place an upper limit at 90% confidence on the dispersion of sigma < 1.9 km/s, and for Tuc V we are not able to obtain any useful limits. All three satellites have low mean metallicities below [Fe/H] = -2.1, but none has a detectable metallicity spread. Using the spectroscopic member stars, we determine proper motions for each satellite from the second Gaia data release. We compute their orbits around the Milky Way, finding that all three objects are currently approaching pericenter. Gru II is on a tightly bound orbit with a pericentric distance of 25 kpc and apocenter of 66 kpc. Tuc V has a significantly more extended orbit, with an apocenter likely beyond 100 kpc, and could be approaching the Milky Way for the first time. The current orbital parameters of Tuc IV are similar to those of Gru II, with a pericenter of 25 kpc. However, a backward integration of the orbit of Tuc IV demonstrates that it collided with the Large Magellanic Cloud with an impact parameter of 4 kpc ~120 Myr ago, deflecting its trajectory and possibly altering its internal kinematics. Based on their sizes, masses, and metallicities, we classify Gru II and Tuc IV as likely dwarf galaxies, but we are not able to draw strong conclusions about the nature of Tuc V. [slightly abridged]

[5]  arXiv:1911.08494 [pdf, other]

Title: Baryonic effects for weak lensing: II. Combination with X-ray data and extended cosmologies

Authors: Aurel Schneider, Alexandre Refregier, Sebastian Grandis, Dominique Eckert, Nicola Stoira, Tomasz Kacprzak, Mischa Knabenhans, Joachim Stadel, Romain Teyssier

Comments: Submitted to JCAP, comments welcome, 30 pages, 10 figures

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

An accurate modelling of baryonic feedback effects is required to exploit the full potential of future weak-lensing surveys such as Euclid or LSST. In this second paper in a series of two, we combine Euclid-like mock data of the cosmic shear power spectrum with an eROSITA X-ray mock of the cluster gas fraction to run a combined likelihood analysis including both cosmological and baryonic parameters. Following the first paper of this series, the baryonic effects (based on the baryonic correction model of Schneider et al. 2019) are included in both the tomographic power spectrum and the covariance matrix. However, this time we assume the more realistic case of a $\Lambda$CDM cosmology with massive neutrinos and we consider several extensions of the currently favoured cosmological model. For the standard $\Lambda$CDM case, we show that including X-ray data reduces the uncertainties on the sum of the neutrino mass by $\sim30$ percent, while there is only a mild improvement on other parameters such as $\Omega_m$ and $\sigma_8$. As extensions of $\Lambda$CDM, we consider the cases of a dynamical dark energy model (wCDM), a $f(R)$ gravity model (fRCDM), and a mixed dark matter model ($\Lambda$MDM) with both a cold and a warm/hot dark matter component. We find that combining weak-lensing with X-ray data only leads to a mild improvement of the constraints on the additional parameters of wCDM, while the improvement is more substantial for both fRCDM and $\Lambda$MDM. Ignoring baryonic effects in the analysis pipeline leads significant false-detections of either phantom dark energy or a light subdominant dark matter component. Overall we conclude that for all cosmologies considered, a general parametrisation of baryonic effects is both necessary and sufficient to obtain tight constraints on cosmological parameters.

[6]  arXiv:1911.08496 [pdf, other]

Title: Mass Assembly of Stellar Systems and their Evolution with the SMA (MASSES) -- Full Data Release

Authors: Ian W. Stephens, Tyler L. Bourke, Michael M. Dunham, Philip C. Myers, Riwaj Pokhrel, John J. Tobin, Héctor G. Arce, Sarah I. Sadavoy, Eduard I. Vorobyov, Jaime E. Pineda, Stella S. R. Offner, Katherine I. Lee, Lars E. Kristensen, Jes K. Jørgensen, Mark A. Gurwell, Alyssa A. Goodman

Comments: Accepted to ApJS

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

We present and release the full dataset for the Mass Assembly of Stellar Systems and their Evolution with the SMA (MASSES) survey. This survey used the Submillimeter Array (SMA) to image the 74 known protostars within the Perseus molecular cloud. The SMA was used in two array configurations to capture outflows for scales $>$30$^{\prime\prime}$ ($>$9000 au) and to probe scales down to $\sim$1$^{\prime\prime}$ ($\sim$300 au). The protostars were observed with the 1.3 mm and 850 $\mu$m receivers simultaneously to detect continuum at both wavelengths and molecular line emission from CO(2-1), $^{13}$CO(2-1), C$^{18}$O(2-1), N$_2$D$^+$(3-2), CO(3-2), HCO$^+$(4-3), and H$^{13}$CO$^+$(4-3). Some of the observations also used the SMA's recently upgraded correlator, SWARM, whose broader bandwidth allowed for several more spectral lines to be observed (e.g., SO, H$_2$CO, DCO$^+$, DCN, CS, CN). Of the main continuum and spectral tracers observed, 84% of the images and cubes had emission detected. The median C$^{18}$O(2-1) linewidth is $\sim$1.0 km s$^{-1}$, which is slightly higher than those measured with single-dish telescopes at scales of 3000-20000 au. Of the 74 targets, six are suggested to be first hydrostatic core candidates, and we suggest that L1451-mm is the best candidate. We question a previous continuum detection toward L1448 IRS2E. In the SVS13 system, SVS13A certainly appears to be the most evolved source, while SVS13C appears to be hotter and more evolved than SVS13B. The MASSES survey is the largest publicly available interferometric continuum and spectral line protostellar survey to date, and is largely unbiased as it only targets protostars in Perseus. All visibility ($uv$) data and imaged data are publicly available at https://dataverse.harvard.edu/dataverse/full_MASSES/.

[7]  arXiv:1911.08497 [pdf, other]

Title: Star Formation in Isolated Dwarf Galaxies Hosting Tidal Debris: Extending the Dwarf-Dwarf Merger Sequence

Authors: Erin Kado-Fong, Jenny E. Greene, Johnny P. Greco, Rachael Beaton, Andy D. Goulding, Sean D. Johnson, Yutaka Komiyama

Comments: 18 pages, 9 figures. Submitted to ApJ

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

Like massive galaxies, dwarf galaxies are expected to undergo major mergers with other dwarfs. However, the end state of these mergers and the role that merging plays in regulating dwarf star formation is uncertain. Using imaging from the Hyper Suprime-Cam Subaru Strategic program, we construct a sample of dwarf-dwarf mergers and examine the star formation and host properties of the merging systems. These galaxies are selected via an automated detection algorithm from a sample of 6875 spectroscopically selected isolated dwarf galaxies at $z<0.12$ and $\log(M_\star/M_\odot)<9.6$ from the Galaxy and Mass Assembly (GAMA) and Sloan Digital Sky Survey (SDSS) spectroscopic campaigns. We find a total tidal feature detection fraction of 3.29% (6.1% when considering only galaxies at $z<0.05$). The tidal feature detection fraction rises strongly as a function of star formation activity; 15%-20% of galaxies with extremely high H$\alpha$ equivalent width (H$\alpha$ EW > 250 Angstrom) show signs of tidal debris. Galaxies that host tidal debris are also systematically bluer than the average galaxy at fixed stellar mass. These findings extend the observed dwarf-dwarf merger sequence with a significant sample of dwarf galaxies, indicating that star formation triggered in mergers between dwarf galaxies continues after coalescence.

[8]  arXiv:1911.08498 [pdf, other]

Title: The REQUIEM Survey I: A Search for Extended Ly-Alpha Nebular Emission Around 31 z>5.7 Quasars

Authors: Emanuele Paolo Farina, Fabrizio Arrigoni-Battaia, Tiago Costa, Fabian Walter, Joseph F. Hennawi, Alyssa B. Drake, Roberto Decarli, Thales A. Gutcke, Chiara Mazzucchelli, Marcel Neeleman, Iskren Georgiev, Anna-Christina Eilers, Frederick B. Davies, Eduardo Bañados, Xiaohui Fan, Masafusa Onoue, Jan-Torge Schindler, Bram P. Venemans, Feige Wang, Jinyi Yang, Sebastian Rabien, Lorenzo Busoni

Comments: 53 pages, too many figures. Accepted for publication in ApJ. For access to the data and codes used in this work, please contact the authors or visit this https URL

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

The discovery of quasars few hundred megayears after the Big Bang represents a major challenge to our understanding of black holes and galaxy formation and evolution. Their luminosity is produced by extreme gas accretion onto black holes, which already reached masses of 10$^9$ M$_\odot$ by z ~ 6. Simultaneously, their host galaxies form hundreds of stars per year, using up gas in the process. To understand which environments are able to sustain the rapid formation of these extreme sources we started a VLT/MUSE effort aimed at characterizing the surroundings of a sample of 5.7 < z < 6.6 quasars dubbed: the Reionization Epoch QUasar InvEstigation with MUSE (REQUIEM) survey. We here present results of our searches for extended Ly-Alpha halos around the first 31 targets observed as part of this program. Reaching 5-sigma surface brightness limits of 0.1-1.1 x 10$^{-17}$ erg/s/cm$^2$/arcsec$^2$ over a 1 arcsec$^2$ aperture, we were able to unveil the presence of 12 Ly-Alpha nebulae, 8 of which are newly discovered. The detected nebulae show a variety of emission properties and morphologies with luminosities ranging from 8 x 10$^{42}$ to 2 x 10$^{44}$ erg/s, FWHMs between 300 and 1700 km/s, sizes < 30 pkpc, and redshifts consistent with those of the quasar host galaxies. As the first statistical and homogeneous investigation of the circum-galactic medium of massive galaxies at the end of the reionization epoch, the REQUIEM survey enables the study of the evolution of the cool gas surrounding quasars in the first 3 Gyr of the Universe. A comparison with the extended Ly-Alpha emission observed around bright (M$_{1450}$ < -25 mag) quasars at intermediate redshift indicates little variations on the properties of the cool gas from z ~ 6 to z ~ 3 followed by a decline in the average surface brightness down to z ~ 2.

[9]  arXiv:1911.08499 [pdf, other]

Title: Lowly polarized light from a highly magnetized jet of GRB 190114C

Authors: N. Jordana-Mitjans, C. G. Mundell, S. Kobayashi, R. J. Smith, C. Guidorzi, I. A. Steele, M. Shrestha, A. Gomboc, M. Marongiu, R. Martone

Comments: The full photometry data will be available in the journal publication

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

We report multi-color optical imaging and polarimetry observations of the afterglow of the first TeV-detected gamma-ray burst, GRB 190114C, using the RINGO3 polarimeter on the 2-m autonomous robotic Liverpool Telescope. Observations begin $201 \,$s after the onset of the GRB and continue until $\sim 7000 \,$ s post-burst. High temporal resolution ($\Delta {\rm t} \simeq 2.3-4.6\, {\rm s}$) and dense sampling of the RINGO3 light curves reveal a chromatic break at ${\rm t} \sim 400- 500\,$s, with initial temporal decay $\alpha \sim 1.5$ flattening to $\alpha \sim 1$ post-break, which we model as a combination of reverse and forward-shock components, with magnetization parameter $R_{\rm B} \sim 40$. The observed polarization degree ${\rm P} \sim 2 - 4\%$ remains steady throughout the first $\sim 2000$-s observation window, with a constant position angle. Broadband spectral energy distribution modeling of the afterglow confirms GRB 190114C is highly obscured (A$_{\rm v, HG} = 1.49 \pm 0.12 \,$mag; N$_{\rm H, HG}= (9.0 \pm 0.03) \times 10^{22}$cm$^{-2}$). The measured polarization is therefore dominated by dust scattering and the intrinsic polarization is low, in contrast to ${\rm P} >10\%$ measured previously for other GRB reverse shocks. We test whether 1st and higher-order inverse Compton scattering in a magnetized reverse shock can explain the low optical polarization and the sub-TeV emission but conclude neither is explained in the reverse shock Inverse Compton model. Instead, the unexpectedly low intrinsic polarization degree in GRB 190114C can be explained if large-scale jet magnetic fields are distorted on timescales prior to reverse shock emission.

[10]  arXiv:1911.08508 [pdf, other]

Title: Parameters Estimation for the Cosmic Microwave Background with Bayesian Neural Networks

Authors: Hector J. Hortua, Riccardo Volpi, Dimitri Marinelli, Luigi Malagò

Comments: 18 pages with 15 figures. Comments are welcome!

Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Machine Learning (cs.LG)

In this paper, we present the first study that compares different models of Bayesian Neural Networks (BNNs) to predict the posterior distribution of the cosmological parameters directly from the Cosmic Microwave Background (CMB) map. We focus our analysis on four different methods to sample the weights of the network during training: Dropout, DropConnect, Reparameterization Trick (RT), and Flipout. We find that Flipout outperforms all other methods regardless of the architecture used, and provides tighter constraints for the cosmological parameters. Additionally, we describe existing strategies for calibrating the networks and propose new ones. We show how tuning the regularization parameter for the scale of the approximate posterior on the weights in Flipout and RT we can produce unbiased and reliable uncertainty estimates, i.e., the regularizer acts as a hyper parameter analogous to the dropout rate in Dropout. The best performances are nevertheless achieved with a more convenient method, in which the network is let free during training to achieve the best uncalibrated performances, and the confidence intervals are then calibrated in a subsequent phase. Furthermore, we claim that the correct calibration of these networks does not change the behavior for the epistemic and aleatoric uncertainties provided for BNNs when the training dataset size changes. The results reported in the paper can be extended to other cosmological datasets in order to estimate confidence regions for features that can be extracted directly from the raw data, such as non-Gaussianity signals or foreground emissions.

[11]  arXiv:1911.08512 [pdf, other]

Title: Inflation models in the light of self-interacting sterile neutrinos

Authors: Arindam Mazumdar, Subhendra Mohanty, Priyank Parashari

Comments: 15 pages, 5 figures

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

Short baseline neutrino experiments, like LSND and MiniBooNE experiments, pointed towards the existence of eV mass scale sterile neutrinos. To reconcile sterile neutrinos with cosmology self interaction between sterile neutrinos has been studied. We analysed Planck cosmic microwave background (CMB) data with self-interacting sterile neutrino (SI$\nu$) and study their impact on inflation models. The fit to the CMB data in SI$\nu$ model is as good as the fit to $\Lambda$CDM model. We find that the spectral index ($n_s$) values shift to $0.9375\pm 0.0058$ in SI$\nu$ model. This has significant impact on the validity of different inflation models. For example the Starobinsky and quartic hilltop model, which were allowed within $\Lambda$CDM cosmology, are ruled out. On the other hand some models like natural and Coleman-Weinberg inflation are now favoured. Therefore, the existence of self interacting sterile neutrinos with eV order of mass will play an important role in the selection of correct inflation model.

[12]  arXiv:1911.08536 [pdf, other]

Title: Strong excess Faraday rotation on the Inside of the Sagittarius spiral arm

Authors: R. Shanahan, S. J. Lemmer, J. M. Stil, H. Beuther, Y. Wang, J. Soler, L. D. Anderson, F. Bigiel, S. C. O. Glover, P. Goldsmith, R. S. Klessen, N. M. McClure-Griffiths, S. Reissl, M. Rugel, R. J. Smith

Comments: Accepted for publication in Astrophysical Journal Letters

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

We present first results for Faraday rotation of compact polarized sources (1 to 2 GHz continuum) in The HI/OH/Recombination line (THOR) survey of the inner Galaxy. In the Galactic longitude range 39 degr < l < 52 degr, we find rotation measures in the range -310 rad/m2 < RM < +4219 rad/m2, with the highest values concentrated within a degree of l = 48 degrees at the Sagittarius arm tangent. Most of the high RMs arise in diffuse plasma, along lines of sight that do not intersect HII regions. For l > 49 degr, RM drops off rapidly, while at l < 47 degr, the mean RM is higher with a larger standard deviation than at l > 49 degr. We attribute the RM structure to the compressed diffuse Warm Ionized Medium in the spiral arm, upstream of the major star formation regions. The Sagittarius arm acts as a significant Faraday screen inside the Galaxy. This has implications for models of the Galactic magnetic field and the expected amount of Faraday rotation of Fast Radio Bursts from their host galaxies. We emphasize the importance of sensitivity to high Faraday depth in future polarization surveys.

[13]  arXiv:1911.08543 [pdf, other]

Title: The Smallest Scale of Hierarchy Survey (SSH). I. Survey Description

Authors: F. Annibali (1), G. Beccari (2), M. Bellazzini (1), M. Tosi (1), F. Cusano (1), D. Paris (5), M. Cignoni (3), L. Ciotti (4), C. Nipoti (4), E. Sacchi (6) ((1) INAF-OAS Bologna (2) ESO, Garching (3) Universitá di Pisa (4) DIFA Bologna (5) INAF-OAR (6) STscI, Baltimore)

Comments: Accepted for publication in MNRAS

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

The Smallest Scale of Hierarchy (SSH) survey is an ongoing strategic large program at the Large Binocular Telescope, aimed at the detection of faint stellar streams and satellites around 45 late-type dwarf galaxies located in the Local Universe within $\simeq$10 Mpc. SSH exploits the wide-field, deep photometry provided by the Large Binocular Cameras in the two wide filters $g$ and $r$. This paper describes the survey, its goals, and the observational and data reduction strategies. We present preliminary scientific results for five representative cases (UGC 12613, NGC 2366, UGC 685, NGC 5477 and UGC 4426) covering the whole distance range spanned by the SSH targets. We reach a surface brightness limit as faint as $\mu(r)\sim$ 31 mag arcsec$^{-2}$ both for targets closer than 4$-$5 Mpc, which are resolved into individual stars, and for more distant targets through the diffuse light. Our analysis reveals the presence of extended low surface brightness stellar envelopes around the dwarfs, reaching farther out than what traced by the integrated light, and as far out as, or even beyond, the observed HI disk. Stellar streams, arcs, and peculiar features are detected in some cases, indicating possible perturbation, accretion, or merging events. We also report on the discovery of an extreme case of Ultra Diffuse Galaxy ($\mu_g(0)=27.9$~mag/arcsec$^2$) in the background of one of our targets, to illustrate the power of the survey in revealing extremely low surface brightness systems.

[14]  arXiv:1911.08545 [pdf, other]

Title: A comparison of cosmological filaments catalogues

Authors: Agustín Rost, Federico Stasyszyn, Luis Pereyra, Héctor J. Martínez

Comments: 12 pages, 16 figures. Submitted to MNRAS

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

In this work we compare three catalogues of cosmological filaments identified in the Sloan Digital Sky Survey by means of different algorithms by Tempel et al., Pereyra et al., and Mart\'inez et al. We analyse how different identification techniques determine differences in the filament statistical properties: length, elongation, redshift distribution, and abundance. We find that the statistical properties of the filaments strongly depend on the identification algorithm. We use a volume limited sample of galaxies to characterise other properties of filaments such as: galaxy overdensity, luminosity function of galaxies, mean galaxy luminosity, filament luminosity, and the overdensity profile of galaxies around filaments. In general, we find that these properties primarily depended on filament length. Shorter filaments have larger overdensities, are more populated by red galaxies, and have better defined galaxy overdensity profiles, than longer filaments. Concluding that galaxies belonging to filaments have characteristic signatures depending on the identification algorithm used.

[15]  arXiv:1911.08546 [pdf]

Title: The Complex Rotational Light Curve of (385446) Manwë-Thorondor, a Multi-Component Eclipsing System in the Kuiper Belt

Authors: David L. Rabinowitz, Susan D. Benecchi, William M. Grundy, Anne J. Verbiscer, Audrey Thirouin

Comments: 34 pages, 5 figures

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

Kuiper Belt Object (385446) Manw\"e-Thorondor is a multi-object system with mutual events predicted to occur from 2014 to 2019. To detect the events, we observed the system at 4 epochs (UT 2016 Aug 25 and 26, 2017 Jul 22 and 25, 2017 Nov 9, and 2018 Oct 6) in g, r, and VR bands using the 4-m SOAR and the 8.1-m Gemini South telescopes at Cerro Pach\'on, Chile and Lowell Observatory ' s 4.3-m Discovery Channel Telescope at Happy Jack, Arizona. These dates overlap the uncertainty range (+/- 0.5 d) for four inferior events (Thorondor eclipsing Manw\"e). We clearly observe variability for the unresolved system with a double-peaked period 11.88190 +/- 0.00005 h and ~0.5 mag amplitude together with much longer-term variability. Using a multi-component model, we simultaneously fit our observations and earlier photometry measured separately for Manw\"e and Thorondor with the Hubble Space Telescope. Our fit suggests Manw\"e is bi-lobed, close to the barbell shape expected for a strengthless body with density ~0.8 g/cm3 in hydrostatic equilibrium. For Manw\"e, we thereby derive maximum width to length ratio ~0.30, surface area equivalent to a sphere of diameter 190 km, geometric albedo 0.06, mass 1.4x1018 kg, and spin axis oriented ~75 deg from Earth ' s line of sight. Changes in Thorondor ' s brightness by ~0.6 mag with ~300-d period may account for the system ' s long-term variability. Mutual events with unexpectedly shallow depth and short duration may account for residuals to the fit. The system is complex, providing a challenging puzzle for future modeling efforts.

[16]  arXiv:1911.08580 [pdf, other]

Title: Long lived dust rings around HD169142

Authors: Claudia Toci (INAF OA Brera), Giuseppe Lodato (Unimi), Davide Fedele (INAF OA Arcetri), Leonardo Testi (ESO), Christophe Pinte (Monash University)

Comments: 8 pages, 5 figures, accepted Apj Letters

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

Recent ALMA observations of the protoplanetary disc around HD~169142 reveal a peculiar structure made of concentric dusty rings: a main ring at $\sim$20 au, a triple system of rings at $\sim 55-75$ au in millimetric continuum emission and a perturbed gas surface density from the $^{12}$CO,$^{13}$CO and C$^{18}$O$(J=2-1)$ surface brightness profile. In this Letter, we perform three-dimensional numerical simulations and radiative transfer modeling exploring the possibility that two giant planets interacting with the disc and orbiting in resonant locking can be responsible for the origin of the observed dust inner rings structure. We find that in this configuration the dust structure is actually long lived while the gas mass of the disc is accreted onto the star and the giant planets, emptying the inner region. In addition, we also find that the innermost planet is located at the inner edge of the dust ring, and can accrete mass from the disc, generating a signature in the dust ring shape that can be observed in mm ALMA observations.

[17]  arXiv:1911.08596 [pdf, other]

Title: Impact of Clouds and Hazes on the Simulated JWST Transmission Spectra of Habitable Zone Planets in the TRAPPIST-1 System

Authors: Thomas J. Fauchez, Martin Turbet, Geronimo L. Villanueva, Eric T. Wolf, Giada Arney, Ravi K. Kopparapu, Andrew Lincowski, Avi Mandell, Julien de Wit, Daria Pidhorodetska, Shawn D. Domagal-Goldman, Kevin B. Stevenson

Comments: 36 pages, 19 figures

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

The TRAPPIST-1 system, consisting of an ultra-cool host star having seven known Earth-size planets will be a prime target for atmospheric characterization with JWST. However, the detectability of atmospheric molecular species may be severely impacted by the presence of clouds and/or hazes. In this work, we perform 3-D General Circulation Model (GCM) simulations with the LMD Generic model supplemented by 1-D photochemistry simulations at the terminator with the Atmos model to simulate several possible atmospheres for TRAPPIST-1e, 1f and 1g: 1) modern Earth, 2) Archean Earth, and 3) CO2-rich atmospheres. JWST synthetic transit spectra were computed using the GSFC Planetary Spectrum Generator (PSG). We find that TRAPPIST-1e, 1f and 1g atmospheres, with clouds and/or hazes, could be detected using JWST's NIRSpec prism from the CO2 absorption line at 4.3 um in less than 15 transits at 3 sigma or less than 35 transits at 5 sigma. However, our analysis suggests that other gases would require hundreds (or thousands) of transits to be detectable. We also find that H2O, mostly confined in the lower atmosphere, is very challenging to detect for these planets or similar systems if the planets' atmospheres are not in a moist greenhouse state. This result demonstrates that the use of GCMs, self-consistently taking into account the effect of clouds and sub-saturation, is crucial to evaluate the detectability of atmospheric molecules of interest as well as for interpreting future detections in a more global (and thus robust and relevant) approach.

[18]  arXiv:1911.08627 [pdf, other]

Title: The chemical evolution of the dwarf Spheroidal galaxy Sextans

Authors: R. Theler, P. Jablonka, C. Lardo, P. North, M. Irwin, G. Battaglia, V. Hill, E. Tolstoy, K. Venn, A. Helmi, A. Kaufer, R. Lucchesi, F. Primas, M. Shetrone

Comments: Submitted to A&A

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

We present the analysis of the FLAMES dataset targeting the central 25 arcmin region of the Sextans dSph. This dataset is the third major part of the high resolution spectroscopic section of the ESO large program 171.B-0588(A) obtained by the Dwarf galaxy Abundances and Radial-velocities Team (DART). Our sample is composed of red giant branch stars down to the level of the horizontal branch in Sextans. It allows to address questions related to both stellar nucleosynthesis and galaxy evolution. We provide metallicities for 81 stars, which cover the wide [Fe/H]=$-$3.2 to $-$1.5 dex range. The abundances of 10 other elements are derived: Mg, Ca, Ti, Sc, Cr, Mn, Co, Ni, Ba, and Eu. Despite its small mass, Sextans is a chemically evolved system, with evidence for the contribution of core-collapse and Type Ia supernovae as well as low metallicity AGBs. This new FLAMES sample offers a sufficiently large number of stars with chemical abundances derived at high accuracy to firmly establish the existence of a plateau in [$\alpha$/Fe] at $\sim 0.4$ dex, followed by a decrease above [Fe/H]$\sim-2$ dex. This is in stark similarity with the Fornax and Sculptor dSphs despite their very different masses and star formation histories. This suggests that these three galaxies had very similar star formation efficiencies in their early formation phases, probably driven by the early accretion of smaller galactic fragments, until the UV-background heating impacted them in different ways. The parallel between the Sculptor and Sextans dSph is also striking when considering Ba and Eu. Finally, as to the iron-peak elements, the decline of [Co/Fe] and [Ni/Fe] above [Fe/H]$\sim -2$ implies that the production yields of Ni and Co in SNeIa is lower than that of Fe. The decrease in [Ni/Fe] favours models of SNeIa based on the explosion of double degenerate sub-Chandrasekhar mass white dwarfs.

[19]  arXiv:1911.08634 [pdf, other]

Title: High-Resolution Simulations of Catastrophic Disruptions: Resultant Shape Distributions

Authors: Keisuke Sugiura, Hiroshi Kobayashi, Shu-ichiro Inutsuka

Comments: 16 pages, 8 figures, accepted for publication in Planetary and Space Science

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

The members of asteroid families have various shapes. We investigate the origin of their shapes by high-resolution impact simulations for catastrophic disruptions using a Smoothed Particle Hydrodynamics code. Collisional remnants produced through our simulations of the catastrophic disruptions mainly have spherical or bilobed shapes. However, no flat remnants with the ratio of minor to major axis lengths c/a < 0.5 are formed. The results of the simulations provide various shapes of asteroids and explain most of the shapes in asteroid families that are supposed to be produced through catastrophic disruptions. However, the present simulations do not explain significantly flat asteroids. We suggest that these flat asteroids may be interlopers or formed through low-velocity collisions between member asteroids.

[20]  arXiv:1911.08640 [pdf, other]

Title: Differences in radio emission from similar M dwarfs in the binary system Ross 867-8

Authors: L. H. Quiroga-Nuñez, H. T. Intema, J. R. Callingham, J. Villadsen, H. J. van Langevelde, P. Jagannathan, T. W. Shimwell, E. P. Boven

Comments: Accepted for publication in A&A

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

Serendipitously, we have rediscovered radio emission from the binary system Ross 867 (M4.5V) and Ross 868 (M3.5V) while inspecting archival Giant Metrewave Radio Telescope (GMRT) observations. The binary system consists of two M-dwarf stars that share common characteristics such as spectral type, astrometric parameters, age and emission at infrared, optical and X-rays frequencies. The GMRT data at 610 MHz taken on July 2011 shows that the radio emission from Ross 867 is polarized and highly variable on hour time scales with a peak flux of 10.4 $\pm$ 0.7 mJy/beam. Additionally, after reviewing archival data from several observatories (VLA, GMRT, JVLA and LOFAR), we confirm that although both stars are likely coeval, only Ross 867 has been detected, while Ross 868 remains undetected at radio wavelengths. As they have a a large orbital separation, this binary stellar system provides a coeval laboratory to examine and constrain the stellar properties linked to radio activity in M dwarfs. We speculate that the observed difference in radio activity between the dwarfs could be due to vastly different magnetic field topologies or that Ross 867 has an intrinsically different dynamo.

[21]  arXiv:1911.08649 [pdf]

Title: NASA Probe Study Report: Farside Array for Radio Science Investigations of the Dark ages and Exoplanets (FARSIDE)

Authors: Jack O. Burns, Gregg Hallinan, Jim Lux, Lawrence Teitelbaum, Jonathon Kocz, Robert MacDowall, Richard Bradley, David Rapetti, Wenbo Wu, Steven Furlanetto, Alex Austin, Andres Romero-Wolf, Tzu-Ching Chang, Judd Bowman, Justin Kasper, Marin Anderson, Zhongwen Zhen, Jonathan Pober, Jordan Mirocha

Comments: 50 pages, NASA Probe final study report. arXiv admin note: text overlap with arXiv:1907.05407

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

This is the final report submitted to NASA for a Probe-class concept study of the "Farside Array for Radio Science Investigations of the Dark ages and Exoplanets" (FARSIDE), a low radio frequency interferometric array on the farside of the Moon. The design study focused on the instrument, a deployment rover, the lander and base station, and delivered an architecture broadly consistent with the requirements for a Probe mission. This notional architecture consists of 128 dipole antennas deployed across a 10 km area by a rover, and tethered to a base station for central processing, power and data transmission to the Lunar Gateway, or an alternative relay satellite. FARSIDE would provide the capability to image the entire sky each minute in 1400 channels spanning frequencies from 150 kHz to 40 MHz, extending down two orders of magnitude below bands accessible to ground-based radio astronomy. The lunar farside can simultaneously provide isolation from terrestrial radio frequency interference, auroral kilometric radiation, and plasma noise from the solar wind. This would enable near-continuous monitoring of the nearest stellar systems in the search for the radio signatures of coronal mass ejections and energetic particle events, and would also detect the magnetospheres for the nearest candidate habitable exoplanets. Simultaneously, FARSIDE would be used to characterize similar activity in our own solar system, from the Sun to the outer planets. Through precision calibration via an orbiting beacon, and exquisite foreground characterization, FARSIDE would also measure the Dark Ages global 21-cm signal at redshifts from 50-100. It will also be a pathfinder for a larger 21-cm power spectrum instrument by carefully measuring the foreground with high dynamic range.

[22]  arXiv:1911.08661 [pdf, other]

Title: Stellar Magnetic Activity and "Butterfly Diagram" of Kepler-63

Authors: Yuri Netto, Adriana Valio

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

Context. The study of young solar type stars is fundamental for a better understanding of the magnetic activity of the Sun. As a planet in transit crosses in front of its host star, a darkspot on the stellar surface may be occulted, causing a detectable variation in the light curve. Kepler-63 is a young solar-like star withan age of only 210 Myr that exhibit photometric variations compatible with spot signatures. Since its orbiting planet is in an almostpolar orbit, different latitudes of the star can be probed by the method of spot transit mapping. Methods. A total of 150 transits of Kepler-63b were observed in the short cadence light curve, corresponding to a total duration of about 4 years. Each transit light curve was fit by a model that simulates planetary transits and allows the inclusion of starspots on the surface of the host star. This enables the physical characterisation of the spots size, intensity, and location. We determine the spot position in a reference frame that rotates with the star, and thus obtain the latitudinal distribution of the spots. Results. A total of 297 spots were fit and their sizes, intensities, and positions determined. The latitude distribution of spots exhibits a bimodality with a lack of spots around 34{\deg}. The high latitude spots dominate the magnetic cycle of Kepler-63. For a mean stellar rotation period of 5.400d, 59 spots were found at approximately the same longitude and latitude on a later transit. Conclusions. Due to the geometry of the Kepler-63 system, we were able to build a starspot "butterfly diagram". It was also possible to infer Kepler-63 differential rotation from the presence of spots at different latitudes. This star was found to rotate almost rigidly with a period of 5.400d and relative shear close to 0.01% for latitudes less than 34{\deg}, whereas the high latitudes do not follow a well behaved pattern.

[23]  arXiv:1911.08664 [pdf, other]

Title: Globular Cluster Systems and X-Ray Atmospheres in Galaxies

Authors: Gretchen L. H. Harris, Iurii V. Babyk, William E. Harris, Brian R. McNamara

Comments: In press for Astrophysical Journal

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

We compare the empirical relationships between the mass of a galaxy's globular system M_GCS, the gas mass in the hot X-ray atmosphere M_X within a fiducial radius of 5 r_e, the total gravitational mass M_grav within 5 r_e, and lastly the total halo mass M_h calibrated from weak lensing. We use a sample of 45 early-type galaxies (ETGs) for which both GCS and X-ray data are available; all the galaxies in our sample are relatively high-mass ones with M_h > 10^12 M_sun. We find that M_X ~ M_h^1.0, similar to the previously known scaling relation M_GCS ~ M_h^1.0. Both components scale much more steeply than the more well known dependence of total stellar mass M_star ~ M_h^0.3 for luminous galaxies. These results strengthen previous suggestions that feedback had little effect on formation of the globular cluster system. The current data are also used to measure the relative mass fractions of baryonic matter and dark matter (DM) within 5 r_e. We find a strikingly uniform mean of <f_DM> = 0.83 with few outliers and an rms scatter of +-0.07. This result is in good agreement with two recent suites of hydrodynamic galaxy formation models.

[24]  arXiv:1911.08667 [pdf, ps, other]

Title: Quasi-simultaneous Spectroscopic and Multi-band Photometric Observations of Blazar S5 0716+714 during 2018-2019

Authors: Hai-Cheng. Feng, H. T. Liu, J. M. Bai, L. F. Xing, Y. B. Li, M. Xiao, Y. X. Xin

Comments: 28 pages, 11 figures, accepted in ApJ

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

In order to study short timescale optical variability of $\gamma$-ray blazar S5 0716+714, quasi-simultaneous spectroscopic and multi-band photometric observations were performed from 2018 November to 2019 March with the 2.4 m optical telescope located at Lijiang Observatory of Yunnan Observatories. The observed spectra are well fitted with a power-law $F_{\lambda}=A\lambda ^{-\alpha}$ (spectral index $\alpha >0$). Correlations found between $\dot{\alpha}$, $\dot{A}$, $\dot{A}/A$, $\dot{F_{\rm{\lambda}}}$, and $\dot{F_{\rm{\lambda}}}/F_{\rm{\lambda}}$ are consistent with the trend of bluer-when-brighter (BWB). \textbf{The same case is for colors, magnitudes, color variation rates, and magnitude variation rates of photometric observations.} The variations of $\alpha$ lead those of $F_{\rm{\lambda}}$. Also, the color variations lead the magnitude variations. The observational data are mostly distributed in the I(+,+) and III(-,-) quadrants of coordinate system. Both of spectroscopic and photometric observations show BWB behaviors in S5 0716+714. The observed BWB may be explained by the shock-jet model, and its appearance may depend on the relative position of the observational frequency ranges with respect to the synchrotron peak frequencies, e.g., at the left of the peak frequencies. \textbf{Fractional variability amplitudes are $F_{\rm{var}}\sim 40\%$ for both of spectroscopic and photometric observations. Variations of $\alpha$ indicate variations of relativistic electron distribution producing the optical spectra. }

[25]  arXiv:1911.08675 [pdf, other]

Title: Exploring the origin of moving groups and diagonal ridges by simulations of stellar orbits and birthplaces

Authors: Douglas A. Barros, Angeles Pérez-Villegas, Jacques R. D. Lépine, Tatiana A. Michtchenko, Ronaldo S. S. Vieira

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

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

The present paper is the culminating one of a series aimed to contribute to the understanding of the kinematic structures of the solar neighbourhood (SN), explaining the origin of the Local Arm and relating the moving groups with the spiral-arms resonances in the disk. With a model for the Galactic potential, with the Sun inside the spiral corotation resonance (CR), we integrate the 2D orbits of test particles distributed in birthplaces along the main spiral arms, the Local Arm, and in the axisymmetric disk. A comparison of the resulting U-V plane of the SN with that provided by Gaia DR2 confirms our previous conclusion that the moving groups of Coma Berenices, Pleiades, and Hyades are associated with the CR, and that the Hercules stream is formed by the bulk of high-order inner Lindblad resonances. The kinematic structures result from stellar orbits trapped by the spiral resonances in a timespan of ~ 1 Gyr, indicating the long-living nature of the spiral structure and challenging recent arguments in favor of short-lived structures originated from incomplete phase mixing in the Galactic disk. As a byproduct, our simulations give some insight into the birthplaces of the stars presently located in the SN; the majority of stars of the main moving groups and the Hercules stream were likely born in the Local Arm, while stars of the Sirius group possibly originated from the outer segment of the Sagittarius-Carina arm. We also propose the spiral resonances as the dynamical origin for the diagonal ridges in the Galactic distribution of rotation velocities.

[26]  arXiv:1911.08685 [pdf, other]

Title: Star Formation in Accretion Disks and SMBH Growth

Authors: Alexander J. Dittmann, M. Coleman Miller

Comments: 13 pages, 5 figures, 1 table

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

Accretion disks around active galactic nuclei are potentially unstable to star formation at large radii. We note that when the compact objects formed from some of these stars spiral into the central supermassive black hole, there is no radiative feedback and therefore the accretion rate is not limited by radiation forces. Using a set of accretion disk models, we calculate the accretion rate onto the central supermassive black hole in both gas and compact objects. We find that the timescale for a supermassive black hole to double in mass can decrease by factors ranging from $\sim0.7$ to as low as $\sim0.1$ in extreme cases, compared to gas accretion alone. Our results suggest that the formation of extremely massive black holes at high redshift may occur without prolonged super-Eddington gas accretion or very massive seed black holes. We comment on potential observational signatures as well as implications for other observations of active galactic nuclei.

[27]  arXiv:1911.08687 [pdf, other]

Title: Tidally Excited Oscillations in Heartbeat Binary Stars: Pulsation Phases and Mode Identification

Authors: Zhao Guo, Avi Shporer, Kelly Hambleton, Howard Isaacson

Comments: ApJ accepted

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

Tidal forces in eccentric binary stars known as heartbeat stars excite detectable oscillations that shed light on the processes of tidal synchronization and circularization. We examine the pulsation phases of tidally excited oscillations (TEOs) in heartbeat binary systems. The target list includes four published heartbeat binaries and four additional systems observed by {\it Kepler}. To the first order, the pulsation phases of TEOs can be explained by the geometric effect of the dominant $l=2$, $m=0$, or $\pm 2$ modes assuming pulsations are adiabatic. We found that this simple theoretical interpretation can account for more than half of the systems on the list, assuming their spin and orbit axes are aligned. We do find significant deviations from the adiabatic predictions for some other systems, especially for the misaligned binary KIC 8164262. The deviations can potentially help to probe the non-adiabaticity of pulsation modes as well as resonances in the tidal forcing.

[28]  arXiv:1911.08740 [pdf, other]

Title: New insights in giant molecular cloud hosting S147/S153 complex: signatures of interacting clouds

Authors: J.S. Dhanya, L. K. Dewangan, D. K. Ojha, S. Mandal

Comments: 22 pages, 8 figures, Accepted for publication in The Publications of the Astronomical Society of Japan (PASJ)

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

In order to understand the formation of massive OB stars, we report a multi-wavelength observational study of a giant molecular cloud hosting the S147/S153 complex (size ~90 pc X 50 pc). The selected complex is located in the Perseus arm, and contains at least five HII regions (S147, S148, S149, S152, and S153) powered by massive OB stars having dynamical ages of ~0.2 - 0.6 Myr. The Canadian Galactic Plane Survey 12CO line data (beam size ~100".4) trace the complex in a velocity range of [-59, -43] km/s, and also reveal the presence of two molecular cloud components around -54 and -49 km/s in the direction of the complex. Signatures of the interaction/collision between these extended cloud components are investigated through their spatial and velocity connections. These outcomes suggest the collision of these molecular cloud components about 1.6 Myr ago. Based on the observed overlapping zones of the two clouds, the collision axis appears to be parallel to the line-of-sight. Deep near-infrared photometric analysis of point-like sources shows the distribution of infrared-excess sources in the direction of the overlapping zones of the molecular cloud components, where all the HII regions are also spatially located. All elements put together, the birth of massive OB stars and embedded infrared-excess sources seems to be triggered by two colliding molecular clouds in the selected site. High resolution observations of dense gas tracer will be required to further confirm the proposed scenario.

[29]  arXiv:1911.08778 [pdf, other]

Title: AT 2018cow VLBI: No Long-Lived Relativistic Outflow

Authors: Michael F. Bietenholz, Raffaella Margutti, Deanne Coppejans, Kate D. Alexander, Megan Argo, Norbert Bartel, Tarraneh Eftekhari, Dan Milisavljevic, Giacomo Terreran, Edo Berger

Comments: Accepted for publication in MNRAS 3 figurs]es

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

We report on VLBI observations of the fast and blue optical transient (FBOT), AT 2018cow. At ~62 Mpc, AT 2018cow is the first relatively nearby FBOT. The nature of AT 2018cow is not clear, although various hypotheses from a tidal disruption event to different kinds of supernovae have been suggested. It had a very fast rise time (3.5 d) and an almost featureless blue spectrum although high photospheric velocities (40,000 km s$^{-1}$) were suggested early on. The X-ray luminosity was very high, ~$1.4 \times 10^{43}$ erg s$^{-1}$, larger than those of ordinary SNe, and more consistent with those of SNe associated with gamma-ray bursts. Variable hard X-ray emission hints at a long-lived "central engine." It was also fairly radio luminous, with a peak 8.4-GHz spectral luminosity of ~$4 \times 10^{28}$ erg s$^{-1}$ Hz$^{-1}$, allowing us to make VLBI observations at ages between 22 and 287 d. We do not resolve AT 2018cow. Assuming a circularly symmetric source, our observations constrain the average apparent expansion velocity to be <0.49$c$ by t = 98 d (3$\sigma$ limit). We also constrain the proper motion of AT 2018cow to be <0.51$c$. Since the radio emission generally traces the fastest ejecta, our observations make the presence of a long-lived relativistic jet with a lifetime of more than one month very unlikely.

[30]  arXiv:1911.08788 [pdf, other]

Title: CTA 102 -- year over year receiving you

Authors: M. Zacharias, M. Boettcher, F. Jankowsky, J.-P. Lenain, S.J. Wagner, A. Wierzcholska

Comments: 8 pages; Proceedings paper of "High Energy Phenomena in Relativistic Outflows VII - HEPRO VII", held 9-12 July 2019 at Facultat de F\'isica, Universitat de Barcelona, Spain; accepted by PoS

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

The FSRQ CTA 102 (z=1.032) has been tremendously active over the last few years. During its peak activity lasting several months in late 2016 and early 2017, the gamma-ray and optical fluxes rose by up to a factor 100 above the quiescence level. We have interpreted the peak activity as the ablation of a gas cloud by the relativistic jet, which can nicely account for the months-long lightcurve in 2016 and 2017. The peak activity was in the middle of a 2-year-long high-state, which was characterized by increased fluxes and increased rms variability compared to the previous low-states, and which was flanked by two bright flares. In this presentation, we put the cloud-ablation scenario into the broader context of the 2-year-long high-state.

[31]  arXiv:1911.08819 [pdf, other]

Title: The impact of progenitor asymmetries on the neutrino-driven convection in core-collapse supernovae

Authors: Rémi Kazeroni, Ernazar Abdikamalov

Comments: 15 pages, 16 figures. Submitted to MNRAS

Subjects: Solar and Stellar Astrophysics (astro-ph.SR); High Energy Astrophysical Phenomena (astro-ph.HE); Fluid Dynamics (physics.flu-dyn)

The explosion of massive stars in core-collapse supernovae may be aided by the convective instabilities that develop in their innermost nuclear burning shells. The resulting fluctuations support the explosion by generating additional turbulence behind the supernova shock. It was suggested that the buoyant density perturbations arising from the interaction of the pre-collapse asymmetries with the shock may be the primary contributor to the enhancement of the neutrino-driven turbulent convection in the post-shock region. Employing three-dimensional numerical simulations of a toy model, we investigate the impact of such density perturbations on the post-shock turbulence. We consider a wide range of perturbation parameters. The spatial scale and the amplitude of the perturbations are found to be of comparable importance. The turbulence is particularly enhanced when the perturbation frequency is close to that of the convective turnovers in the gain region. Our analysis confirms that the buoyant density perturbations is indeed the main source of the additional turbulence in the gain region, validating the previous order-of-magnitude estimates.

[32]  arXiv:1911.08852 [pdf, other]

Title: Stellar cosmic rays as an important source of ionisation in protoplanetary disks: a disk mass dependent process

Authors: D. Rodgers-Lee, A. M. Taylor, T. P. Downes, T. P. Ray

Comments: 11 pages, 6 figures, accepted for publication in MNRAS

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

We assess the ionising effect of low energy protostellar cosmic rays in protoplanetary disks around a young solar mass star for a wide range of disk parameters. We assume a source of low energy cosmic rays located close to the young star which travel diffusively through the protoplanetary disk. We use observationally inferred values from nearby star-forming regions for the total disk mass and the radial density profile. We investigate the influence of varying the disk mass within the observed scatter for a solar mass star. We find that for a large range of disk masses and density profiles that protoplanetary disks are "optically thin" to low energy ($\sim$3 GeV) cosmic rays. At $R\sim10$au, for all of the disks that we consider ($M_\mathrm{disk}=6.0\times10^{-4} - 2.4\times 10^{-2}M_\odot$), the ionisation rate due to low energy stellar cosmic rays is larger than that expected from unmodulated galactic cosmic rays. This is in contrast to our previous results which assumed a much denser disk which may be appropriate for a more embedded source. At $R\sim70$au, the ionisation rate due to stellar cosmic rays dominates in $\sim$50% of the disks. These are the less massive disks with less steep density profiles. At this radius there is at least an order of magnitude difference in the ionisation rate between the least and most massive disk that we consider. Our results indicate, for a wide range of disk masses, that low energy stellar cosmic rays provide an important source of ionisation at the disk midplane at large radii ($\sim$70au).

[33]  arXiv:1911.08857 [pdf, other]

Title: Are galactic star formation and quenching governed by local, global or environmental phenomena?

Authors: Asa F. L. Bluck, Roberto Maiolino, Sebastian Sanchez, Sara L. Ellison, Mallory D. Thorp, Joanna M. Piotrowska, Hossen Teimoorinia, Kevin A. Bundy

Comments: Accepted for publication in MNRAS. 45 pages; 20 figures

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

We present an analysis of star formation and quenching in the SDSS-IV MaNGA-DR15, utilising over 5 million spaxels from $\sim$3500 local galaxies. We estimate star formation rate surface densities ($\Sigma_{\rm SFR}$) via dust corrected $H\alpha$ flux where possible, and via an empirical relationship between specific star formation rate (sSFR) and the strength of the 4000 Angstrom break (D4000) in all other cases. We train a multi-layered artificial neural network (ANN) and a random forest (RF) to classify spaxels into `star forming' and `quenched' categories given various individual (and groups of) parameters. We find that global parameters (pertaining to the galaxy as a whole) perform collectively the best at predicting when spaxels will be quenched, and are substantially superior to local/ spatially resolved and environmental parameters. Central velocity dispersion is the best single parameter for predicting quenching in central galaxies. We interpret this observational fact as a probable consequence of the total integrated energy from AGN feedback being traced by the mass of the black hole, which is well known to correlate strongly with central velocity dispersion. Additionally, we train both an ANN and RF to estimate $\Sigma_{\rm SFR}$ values directly via regression in star forming regions. Local/ spatially resolved parameters are collectively the most predictive at estimating $\Sigma_{\rm SFR}$ in these analyses, with stellar mass surface density at the spaxel location ($\Sigma_*$) being by far the best single parameter. Thus, quenching is fundamentally a global process but star formation is governed locally by processes within each spaxel.

[34]  arXiv:1911.08859 [pdf, other]

Title: A super-solar metallicity atmosphere for WASP-127b revealed by transmission spectroscopy from HST and Spitzer

Authors: Jessica J. Spake, David K. Sing, Hannah R. Wakeford, Nikolay Nikolov, Thomas Mikal-Evans, Drake Deming, Joanna Barstow, David R. Anderson, Aarynn L. Carter, Michael Gillon, Jayesh M. Goyal, Guillaume Hebrard, Coel Hellier, Tiffany Kataria, Kristine W. F. Lam, A. H. M. J. Triaud

Comments: Submitted to MNRAS

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

The chemical abundances of exoplanet atmospheres may provide valuable information about the bulk compositions, formation pathways, and evolutionary histories of planets. Exoplanets which have large, relatively cloud-free atmospheres, and which orbit bright stars provide the best opportunities for accurate abundance measurements. For this reason, we measured the transmission spectrum of the bright (V~10.2), large (1.37RJ), sub-Saturn mass (0.19MJ) exoplanet WASP-127b across the near-UV to near-infrared wavelength range (0.3 - 5 microns), using the Hubble and Spitzer Space Telescopes. Our results show a feature-rich transmission spectrum, with absorption from Na, H2O, and CO2, as well as wavelength-dependent scattering from small-particle condensates, and a grey absorber which somewhat mutes the molecular absorption features. We ran two types of atmospheric retrieval models: one enforcing chemical equilibrium, and the other which fit the abundances freely. Our retrieved abundances at chemical equilibrium for Na, O and C are all super-solar, with abundances relative to solar values of 51+30-29, 23+15-9, and 33+43-25 respectively. Despite giving conflicting C/O ratios, both retrievals gave super-solar CO2 volume mixing ratios, which adds to the likelihood that WASP-127b's bulk metallicity is super-solar, since CO2 abundance is highly sensitive to atmospheric metallicity. In the future, spectroscopy with JWST will be able to constrain WASP-127b's C/O ratio, and may reveal the formation history of this metal-enriched, highly observable exoplanet.

[35]  arXiv:1911.08861 [pdf, other]

Title: Improved calculations of electron-ion Bremsstrahlung Gaunt factors for astrophysical applications

Authors: Jens Chluba, Andrea Ravenni, Boris Bolliet

Comments: 12 pages + 5 pages appendix and references, 17 figures, to be submitted to MNRAS, BRpack will be made available at www.chluba.de/BRpack

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

Electron-ion Bremsstrahlung (free-free) emission and absorption occur in many astrophysical plasmas for a wide range of physical conditions. This classical problem has been studied multiple times, and many analytical and numerical approximations exist. However, accurate calculations of the transition from the non-relativistic to the relativistic regime remain sparse. Here we provide a comprehensive study of the free-free Gaunt factors for ions with low charge (Z<=10). We compute the Gaunt factor using the expressions for the differential cross section given by Elwert & Haug (EH) and compare to various limiting cases. We develop a new software package, BRpack, for direct numerical applications. This package uses a combination of pre-computed tables and analytical approximations to efficiently cover a wide range of electron and photon energies, providing a representation of the EH Gaunt factor to better than 0.03% precision for Z<=2. Our results are compared to those of previous studies highlighting the improvements achieved here. BRpack should be useful in computations of spectral distortions of the cosmic microwave background, radiative transfer problems during reionization or inside galaxy clusters, and the modeling of galactic free-free foregrounds. The developed computational methods can furthermore be extended to higher energies and ion charge.

[36]  arXiv:1911.08878 [pdf, other]

Title: Revised mass-radius relationships for water-rich terrestrial planets beyond the runaway greenhouse limit

Authors: Martin Turbet, Emeline Bolmont, David Ehrenreich, Pierre Gratier, Jérémy Leconte, Franck Selsis, Nathan Hara, Christophe Lovis

Comments: Submitted for publication to A&A. The abstract is abridged to meet ArXiv size limit

Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Atmospheric and Oceanic Physics (physics.ao-ph); Geophysics (physics.geo-ph)

Mass-radius relationships for water-rich terrestrial planets are usually calculated assuming most water is present in condensed (either liquid or solid) form. Planet density estimates are then compared to these mass-radius relationships even when these planets are more irradiated than the runaway greenhouse irradiation limit (around 1.06x the Earth irradiation for planets orbiting a Sun-like star), for which water has been shown to be unstable in condensed form and should rather form a thick H2O-dominated atmosphere. Here we use the LMD Generic numerical climate model to derive new mass-radius relationships appropriate for water-rich terrestrial planets located beyond the runaway greenhouse limit, i.e. planets endowed with a steam, water-dominated atmosphere. These new mass-radius relationships significantly differ from those traditionnally used in the literature. For a given water-to-rock mass ratio, these new mass-radius relationships lead to planet bulk densities much lower than calculated when water is assumed to be in condensed form. In other words, using traditional mass-radius relationships for planets that are more irradiated than the runaway greenhouse limit tends to dramatically overestimate their bulk water content. In particular, this result applies to TRAPPIST-1b, c and d, that should not have more (assuming planetary core with a terrestrial composition) than 2, 0.3 and 0.08% of water, respectively. In addition, we show with the example of the TRAPPIST-1 multiplanetary system that the jumps in mass-radius relationships (related to the runaway greenhouse transition) can be used to remove usual composition degeneracies in mass-radius relationships. Finally, we provide an empirical formula for the H2O steam atmosphere thickness that can easily be used to construct mass-radius relationships for water-rich, terrestrial planets located beyond the runaway greenhouse limit.

[37]  arXiv:1911.08883 [pdf, other]

Title: White Dwarf Bounds on CHAMPs

Authors: Michael A. Fedderke, Peter W. Graham, Surjeet Rajendran

Comments: 60 pages, 9 figures

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

White dwarfs effectively act as high-gain amplifiers for relatively small energy deposits within their volume via their supernova instability. In this paper, we consider the ways a galactic abundance of $\mathcal{O}(1)$-charged massive relics (i.e., CHAMPs) could trigger this instability, thereby destroying old WD. The dense central core structure formed inside the WD when heavy CHAMPs sink to its center can trigger a supernova via injection of energy during collapse phases, via direct density-enhanced (pycnonuclear) fusion processes of carbon nuclei dragged into the core by the CHAMPs, or via the formation of a black hole (BH) at the center of the WD. In the latter scenario, Hawking radiation from the BH can ignite the star if the BH forms with a sufficiently small mass; if the BH instead forms at large enough mass, heating of carbon nuclei that accrete onto the BH as it grows in size may be able to achieve the same outcome (with the conservative alternative being simply that the WD is devoured by the BH). The known existence of old WD that have not been destroyed by these mechanisms allows us to improve by many orders of magnitude on the existing CHAMP abundance constraints in the regime of large CHAMP mass, $m_X \sim 10^{11}$-$10^{18}\,$GeV. Additionally, in certain regions of parameter space, we speculate that this setup could provide a trigger mechanism for the calcium-rich gap transients: a class of anomalous, sub-luminous supernova events that occur far outside of a host galaxy.

[38]  arXiv:1911.08904 [pdf, other]

Title: New mysteries and challenges from the Toothbrush relic: wideband observations from 550 MHz to 8 GHz

Authors: K. Rajpurohit, M. Hoeft, F. Vazza, L. Rudnick, R. J. van Weeren, D. Wittor, A. Drabent, M. Brienza, F. Loi, E. Bonnassieux, N. Locatelli, R. Kale, C. Dumba

Comments: Submitted to A&A

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

Radio relics are diffuse extended synchrotron sources that originate from shock fronts induced by galaxy cluster mergers. The actual particle acceleration mechanism at the shock fronts is still under debate. The galaxy cluster 1RXS J0603.3+4214 hosts one of the most intriguing examples of radio relics, known as the Toothbrush. We present new wideband radio continuum observations made with uGMRT and VLA. Our new observations, in combination with previously published data, allowed us to carry out a detailed high spatial resolution spectral and curvature analysis of the known diffuse radio emission sources, over a broad range of frequencies. The integrated spectrum of the Toothbrush follows closely a power law over close to 2 decades in frequency, with a spectral index of $-1.16\pm0.02$. We do not find any evidence of spectral steepening below 8 GHz. The subregions of the main Toothbrush also exhibit near-perfect power laws, implying a very regular combination of shock properties across the shock front. Recent numerical simulations show an intriguing similar spectral index, suggesting that the radio spectrum is dominated by the average over the inhomogeneities within the shock, with most of the emission coming from the tail of the Mach number distribution. In contrast to the Toothbrush, the spectrum of the fainter relics show a high frequency steepening. Moreover, also the integrated spectrum of the halo follows a power law from 150 MHz to 3 GHz with a spectral index of $-1.16\pm0.04$. We do not find any evidence for spectral curvature, not even in subareas of the halo. This suggest a homogeneous acceleration throughout the cluster volume. Between the brush region of the Toothbrush and the halo, the color-color analysis revealed emission that was consistent with an overlap between the two different spectral regions.

[39]  arXiv:1911.08910 [pdf, ps, other]

Title: Features of the Flow Structure in the Vicinity of the Inner Lagrangian Point in Polars

Authors: P. B. Isakova, A. G. Zhilkin, D. V. Bisikalo

Comments: 16 pages, 6 figures

Journal-ref: Astronomy Reports, Volume 62, Issue 8, pp.492-501, 2018

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

The structures of plasma flows in close binary systems whose accretors have strong intrinsic magnetic fields are studied. A close binary system with the parameters of a typical polar is considered. The results of three dimensional numerical simulations of the material flow from the donor into the accretor Roche lobe are presented. Special attention is given to the flow structure in the vicinity of the inner Lagrangian point, where the accretion flow is formed. The interaction of the accretion flow material from the envelope of the donor with the magnetic field of the accretor results in the formation of a hierarchical structure of the magnetosphere, because less dense areas of the accretion flow are captured by the magnetic field of the white dwarf earlier than more dense regions. Taking into account this kind of magnetosphere structure can affect analysis results and interpretation of the observations.

[40]  arXiv:1911.08912 [pdf, other]

Title: Extreme & High Synchrotron Peak $\rm γ$-ray Blazars beyond 4FGL: The 2BIGB $\rm γ$-ray catalog

Authors: Bruno Arsioli, Yu-Ling Chang, Blessing Musiimenta

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

We present the results of a gamma-ray likelihood analysis over all the extreme and high synchrotron peak blazars (EHSP & HSP) from the 3HSP sample. We investigate 2013 multifrequency seed positions under the eyes of Fermi Large Area Telescope, integrating over 11 years of observations. We report on 1160 gamma-ray signatures detected down to the 3$\sigma$ threshold in the energy range between 500 MeV to 500 GeV. The detections include 235 additional sources concerning 4FGL, all confirmed via high-energy TS maps, and represent an improvement of ~25% for the number of EHSP & HSP currently described in gamma-rays. We build the gamma-ray spectral energy distribution for all the 1160 sources, delivering to the very high-energy community a dedicated spectral description of the entire 3HSP population. We plot the gamma-ray logN-logS for the 3HSP sample, and also for the EHSP & HSP subsamples. We measure the total contribution of HSP+EHSP to the extragalactic gamma-ray background, which reaches up to ~33% at 100 GeV. Also, we show how does the gamma-ray detectability improves according to the synchrotron peak flux as represented by the Figure of Merit (FOM) parameter. We highlight that the search for TeV peaked blazars may benefit from considering HSP and EHSP as a whole, instead of EHSPs only. We entitle this gamma-ray database as Second Brazil-ICRANet Gamma-ray Blazar catalog, with the acronym 2BIGB. All information will be available on public data repositories (Brazilian Science Data Center-BSDC, OpenUniverse, and GitHub at https://github.com/BrunoArsioli ), including the broadband models and the spectral energy distribution data points.

[41]  arXiv:1911.08961 [pdf, other]

Title: A very-high-energy component deep in the Gamma-ray Burst afterglow

Authors: H. Abdalla R. Adam F. Aharonian F. Ait Benkhali E.O. Anguener M. Arakawa, C. Arcaro, C. Armand, H. Ashkar, M. Backes, V. Barbosa Martins, M. Barnard Y. Becherini, D. Berge, K. Bernloehr, E. Bissaldi, R. Blackwell, M. Boettcher, C. Boisson, J. Bolmont, S. Bonnefoy, J. Bregeon, M. Breuhaus, F. Brun, P. Brun, M. Bryan, M. Buechele, T. Bulik, T. Bylund, M. Capasso, S. Caroff, A. Carosi, S. Casanova, M. Cerruti, T. Chand, S. Chandra, A. Chen, S. Colafrancesco, M. Curylo, I.D. Davids, C. Deil, J. Devin, P. deWilt, L. Dirson, A. Djannati-Atai, A. Dmytriiev, A. Donath, V. Doroshenko, J. Dyks, K. Egberts, G. Emery, J.-P. Ernenwein, S. Eschbach, K. Feijen, S. Fegan, A. Fiasson, G. Fontaine, S. Funk, M. Fuessling, S. Gabici, Y.A. Gallant, F. Gate, G. Giavitto, L. Giunti, D. Glawion, J.F. Glicenstein, et al. (162 additional authors not shown)

Comments: Preprint version of Nature paper. Contacts: E.Ruiz-Velasco, F. Aharonian, E.Bissaldi, C.Hoischen, R.D Parsons, Q.Piel, A.Taylor, D.Khangulyan

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

Gamma-ray bursts (GRBs) are brief flashes of gamma rays, considered to be the most energetic explosive phenomena in the Universe. The emission from GRBs comprises a short (typically tens of seconds) and bright prompt emission, followed by a much longer afterglow phase. During the afterglow phase, the shocked outflow -- produced by the interaction between the ejected matter and the circumburst medium -- slows down, and a gradual decrease in brightness is observed. GRBs typically emit most of their energy via gamma-rays with energies in the kiloelectronvolt-to-megaelectronvolt range, but a few photons with energies of tens of gigaelectronvolts have been detected by space-based instruments. However, the origins of such high-energy (above one gigaelectronvolt) photons and the presence of very-high-energy (more than 100 gigaelectronvolts) emission have remained elussive. Here we report observations of very-high-energy emission in the bright GRB 180720B deep in the GRB afterglow -ten hours after the end of the prompt emission phase, when the X-ray flux had already decayed by four orders of magnitude. Two possible explanations exist for the observed radiation: inverse Compton emission and synchrotron emission of ultrarelativistic electrons. Our observations show that the energy fluxes in the X-ray and gamma-ray range and their photon indices remain comparable to each other throughout the afterglow. This discovery places distinct constraints on the GRB environment for both emission mechanisms, with the inverse Compton explanation alleviating the particle energy requirements for the emission observed at late times. The late timing of this detection has consequences for the future observations of GRBs at the highest energies.

[42]  arXiv:1911.08977 [pdf, ps, other]

Title: Rotation of molecular clouds in M~51

Authors: J. Braine, A. Hughes, E. Rosolowsky, P. Gratier, D. Colombo, S. Meidt, E. Schinnerer

Comments: Accepted by Astronomy and Astrophysics

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

The grand-design spiral galaxy M~51 was observed at 40pc resolution in CO(1--0) by the PAWS project. A large number of molecular clouds were identified and we search for velocity gradients in two high signal-to-noise subsamples, containing 682 and 376 clouds. The velocity gradients are found to be systematically prograde oriented, as was previously found for the rather flocculent spiral M~33. This strongly supports the idea that the velocity gradients reflect cloud rotation, rather than more random dynamical forces, such as turbulence. Not only are the gradients prograde, but their $\frac{\partial v}{\partial x}$ and $\frac{\partial v}{\partial y}$ coefficients follow galactic shear in sign, although with a lower amplitude. No link is found between the orientation of the gradient and the orientation of the cloud. The values of the cloud angular momenta appear to be an extension of the values noted for galactic clouds despite the orders of magnitude difference in cloud mass. Roughly 30\% of the clouds show retrograde velocity gradients. For a strictly rising rotation curve, as in M~51, gravitational contraction would be expected to yield strictly prograde rotators within an axisymmetric potential. In M~51, the fraction of retrograde rotators is found to be higher in the spiral arms than in the disk as a whole. Along the leading edge of the spiral arms, a majority of the clouds are retrograde rotators. While this work should be continued on other nearby galaxies, the M~33 and M~51 studies have shown that clouds rotate and that they rotate mostly prograde, although the amplitudes are not such that rotational energy is a significant support mechanism against gravitation. In this work, we show that retrograde rotation is linked to the presence of a spiral gravitational potential.

[43]  arXiv:1911.08988 [pdf, other]

Title: The presupernova core mass-radius relation of massive stars: understanding its formation and evolution

Authors: Alessandro Chieffi, Marco Limongi

Comments: 22 pages, 10 figures

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

We present a fine grid of solar metallicity models of massive stars (320 in the range 12$\leq$M(\msun)$\leq$27.95), extending from the Main Sequence up to the onset of the collapse, in order to quantitatively determine how their compactness $\xi_{2.5}$ (as defined by O'Connor $\&$ Ott, 2011, ApJ 730, 70) scales with the Carbon Oxygen core mass at the beginning of the core collapse. We find a well defined, not monotonic (but not scattered) trend of the compactness with the Carbon Oxygen core mass that is strictly (and mainly) correlated to the behavior, i.e. birth, growth and disappearance, of the various C convective episodes that follow one another during the advanced evolutionary phases. Though both the mass size of the Carbon Oxygen core and the amount of \nuk{C}{12} left by the He burning play a major role in sculpting the final Mass-Radius relation, it is the abundance of \nuk{C}{12} the ultimate responsible for the final degree of compactness of a star because it controls the ability of the C burning shell to advance in mass before the final collapse.

[44]  arXiv:1911.08991 [pdf, other]

Title: Astrochemistry as a tool to follow the protostellar evolution: the Class I stage

Authors: Eleonora Bianchi, Cecilia Ceccarelli, Claudio Codella, Juan Enrique-Romero, Cecile Favre, Bertrand Lefloch

Comments: 51 pages, 10 figures

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

The latest developments in astrochemistry have shown how some molecular species can be used as a tool to study the early stages of the solar-type star formation process. Among them, the more relevant species are the interstellar complex organic molecules (iCOMs) and the deuterated molecules. Their analysis give us information on the present and past history of protostellar objects. Among the protostellar evolutionary stages, Class I protostars represent a perfect laboratory in which to study the initial conditions for the planet formation process. Indeed, from a physical point of view, the Class I stage is the bridge between the Class 0 phase, dominated by the accretion process, and the protoplanetary disk phase, when planets form. Despite their importance, few observations of Class I protostars exist and very little is known about their chemical content. In this paper we review the (few) existing observations of iCOMs and deuterated species in Class I protostars. In addition, we present new observations of deuterated cyanoacetylene and thioformaldehyde towards the Class I protostar SVS13-A. These new observations allow us to better understand the physical and chemical structure of SVS13-A and compare the cyanoacetylene and thioformaldehyde deuteration with other sources in different evolutionary phases.

[45]  arXiv:1911.09029 [pdf, other]

Title: An In-depth Investigation of Faraday Depth Spectrum Using Synthetic Observations of Turbulent MHD Simulations

Authors: Aritra Basu, Andrew Fletcher, S. A. Mao, Blakesley Burkhart, Rainer Beck, Dominic Schnitzeler

Comments: 30 article-style pages, 11 figures, Accepted to be published in the special issue of MDPI Galaxies on "New Perspectives on Galactic Magnetism"

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

In this paper we present a detailed analysis of the Faraday depth (FD) spectrum and its clean components obtained through the application of the commonly used technique of Faraday rotation measure synthesis to analyze spectro-polarimetric data. In order to directly compare the Faraday depth spectrum with physical properties of a magneto-ionic medium, we generated synthetic broad-bandwidth spectro-polarimetric observations from magnetohydrodynamic (MHD) simulations of a transonic, isothermal, compressible turbulent medium. We find that correlated magnetic field structures give rise to a combination of spiky, localized peaks at certain FD values, and broad structures in the FD spectrum. Although the majority of these spiky FD structures appear narrow, giving an impression of a Faraday thin medium, we show that they arise from strong synchrotron emissivity at that FD. Strong emissivity at a FD can arise because of both strong spatially-local polarized synchrotron emissivity at a FD or accumulation of weaker emissions along the distance through a medium that have Faraday depths within half the width of the rotation measure spread function. Such a complex Faraday depth spectrum is a natural consequence of MHD turbulence when the lines of sight pass through a few turbulent cells. This therefore complicates the convention of attributing narrow FD peaks to presence of a Faraday rotating medium along the line of sight. Our work shows that it is difficult to extract the FD along a line of sight from the Faraday depth spectrum using standard methods for a turbulent medium in which synchrotron emission and Faraday rotation occur simultaneously.

[46]  arXiv:1911.09038 [pdf, other]

Title: Poisson_CCD: A dedicated simulator for modeling CCDs

Authors: Craig Lage, Andrew K. Bradshaw, J. Anthony Tyson

Comments: 37 pages, 27 figures

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

A dedicated simulator, Poisson_CCD, has been constructed which models astronomical CCDs by solving Poisson's equation numerically and simulating charge transport within the CCD. The potentials and free carrier densities within the CCD are self-consistently solved for, giving realistic results for the charge distribution within the CCD storage wells. The simulator has been used to model the CCDs which are being used to construct the LSST digital camera. The simulator output has been validated by comparing its predictions with several different types of CCD measurements, including astrometric shifts, brighter-fatter induced pixel-pixel covariances, saturation effects, and diffusion spreading. The code is open source and freely available.

[47]  arXiv:1911.09043 [pdf, ps, other]

Title: The study of ultraluminous X-ray source UGC6456 ULX

Authors: Alexander Vinokurov, Kirill Atapin, Yulia Solovyeva

Comments: 5 pages, 3 figure. Submitted to Research in Astronomy and Astrophysics (Conference "Modern stellar astronomy - 2019", Nizhnij Arkhyz, Russia)

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

We present preliminary results of a study of the ultraluminous X-ray source UGC6456 ULX. The object is highly variable in both the X-ray (more than 100 times, 0.3-10 keV) and optical (2 times, V band) ranges. The peak X-ray luminosity of UGC6456 ULX exceeds $10^{40}$ erg/s, the absolute magnitude in the bright state exceeds M$_V=-7.6$, which makes it one of the brightest ULXs in the optical range. We found a correlation between the optical and X-ray fluxes, which may indicate that the optical emission is produced by re-processing of the X-rays in outer parts of the optically-thick wind coming from the supercritical accretion disk. Optical spectra of UGC6456 ULX show broad and variable hydrogen and helium emission lines, which also confirms the presence of the strong wind.

[48]  arXiv:1911.09056 [pdf, other]

Title: Fundamental physics with blazar spectra: a critical appraisal

Authors: Giorgio Galanti, Fabrizio Tavecchio, Marco Landoni

Comments: 10 pages, 7 figures, revised version submitted to MNRAS

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

Very-high-energy (VHE) BL Lac spectra extending above $10 \, \rm TeV$ provide a unique opportunity for testing physics beyond the standard model of elementary particle and alternative blazar emission models. We consider the hadron beam, the photon to axion-like particle (ALP) conversion, and the Lorentz invariance violation (LIV) scenarios by analyzing their consequences and induced modifications to BL Lac spectra. In particular, we consider how different processes can provide similar spectral features (e.g. hard tails) and we discuss the ways they can be disentangled. We use HEGRA data of a high state of Markarian 501 and the HESS spectrum of the extreme BL Lac (EHBL) 1ES 0229+200. In addition, we consider two hypothetical EHBLs similar to 1ES 0229+200 located at redshifts $z=0.3$ and $z=0.5$. We observe that both the hadron beam and the photon-ALP oscillations predict a hard tail extending to energies larger than those possible in the standard scenario. Photon-ALP interaction predicts a peak in the spectra of distant BL Lacs at about $20-30 \, \rm TeV$, while LIV produces a strong peak in all BL Lac spectra around $\sim 100 \, \rm TeV$. The peculiar feature of the photon-ALP conversion model is the production of oscillations in the spectral energy distribution, so that its detection/absence can be exploited to distinguish among the considered models. The above mentioned features coming from the three models may be detected by the upcoming Cherenkov Telescope Array (CTA). Thus, future observations of BL Lac spectra could eventually shed light about new physics and alternative blazar emission models, driving fundamental research towards a specific direction.

[49]  arXiv:1911.09073 [pdf, other]

Title: Constraints on neutrinos and WDM Hints, neutrino bounds and WDM constraints from SDSS DR14 Lyman-$α$ and Planck full-survey data

Authors: Nathalie Palanque-Delabrouille, Christophe Yèche, Nils Schöneberg, Julien Lesgourgues, Michael Walther, Solène Chabanier, Eric Armengaud

Comments: submitted to JCAP

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

The Ly-$\alpha$ forest 1D flux power spectrum is a powerful probe of several cosmological parameters. Assuming a $\Lambda$CDM cosmology including massive neutrinos, we find that the latest SDSS DR14 BOSS and eBOSS Ly-$\alpha$ forest data is in very good agreement with current weak lensing constraints on $(\Omega_m, \sigma_8)$ and has the same small level of tension with Planck. We did not identify a systematic effect in the data analysis that could explain this small tension, but we show that it can be reduced in extended cosmological models where the spectral index is not the same on the very different times and scales probed by CMB and Ly-$\alpha$ data. A particular case is that of a $\Lambda$CDM model including a running of the spectral index on top of massive neutrinos. With combined Ly-$\alpha$ and Planck data, we find a slight (3$\sigma$) preference for negative running, $\alpha_s= -0.010 \pm 0.004$ (68% CL). Neutrino mass bounds are found to be robust against different assumptions. In the $\Lambda$CDM model with running, we find $\sum m_\nu <0.11$ eV at the 95% confidence level for combined Ly-$\alpha$ and Planck (temperature and polarisation) data, or $\sum m_\nu < 0.09$ eV when adding CMB lensing and BAO data. We further provide strong and nearly model-independent bounds on the mass of thermal warm dark matter: $m_X > 10\;\mathrm{keV}$ (95% CL) from Ly-$\alpha$ data alone.

Cross-lists for Thu, 21 Nov 19

[50]  arXiv:1911.08263 (cross-list from physics.plasm-ph) [pdf, ps, other]

Title: Mach number and plasma beta dependence of the ion temperature perpendicular to the external magnetic field in the transition region of perpendicular collisionless shocks

Authors: Ryo Yamazaki, Ayato Shinoda, Takayuki Umeda, Shuichi Matsukiyo

Comments: 6 pages, 3 figures, 1 table. AIP Advances, in press

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

Ion temperature anisotropy is a common feature for (quasi-)perpendicular collisionless shocks. By using two-dimensional full particle simulations, it is shown, that the ion temperature component perpendicular to the shock magnetic field at the shock foot region is proportional to the square of the Alfven Mach number divided by the plasma beta. This result is also explained by a simple analytical argument, in which the reflected ions get energy from upstream plasma flow. By comparing our analytic and numerical results, it is also confirmed that the fraction of the reflected ions hardly depends on the plasma beta and the Alfven Mach number when the square of the Alfven Mach number divided by the plasma beta is larger than about 20.

[51]  arXiv:1911.08502 (cross-list from hep-ph) [pdf, other]

Title: Scalar induced resonant sterile neutrino production in the early Universe

Authors: F. Bezrukov, A. Chudaykin, D. Gorbunov

Comments: 29 pages, 6 figures

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

It has been recently suggested \cite{Bezrukov:2017ike,Bezrukov:2018wvd} that a cosmic scalar field can completely change the keV-scale sterile neutrino production in the early Universe. Its effect may, for various parameter choices, either suppress sterile neutrino production and make moderate active-sterile mixing cosmologically acceptable, or increase the production and generate considerable dark matter component out of sterile neutrino with otherwise negligible mixing with SM. In this paper we provide analytic estimates and corresponding details of the numerical calculations performed in \cite{Bezrukov:2018wvd} in the case of resonant amplification of the sterile neutrino production. We also discuss phenomenological and theoretical issues related to the successful implementation of this idea in fully realistic extensions of the Standard Model of particle physics.

[52]  arXiv:1911.08550 (cross-list from hep-ph) [pdf, other]

Title: MeV-GeV $γ$-ray telescopes probing gravitino LSP with coexisting axino NLSP as dark matter in the $μν$SSM

Authors: German A. Gomez-Vargas, Daniel E. Lopez-Fogliani, Carlos Munoz, Andres D. Perez

Comments: 18 pages, 4 figures. arXiv admin note: substantial text overlap with arXiv:1911.03191

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

In $R$-parity violating supersymmetry, the gravitino as the lightest supersymmetric particle (LSP) is a good candidate for dark matter, with the interesting characteristic to be detectable through $\gamma$-ray telescopes. We extend this analysis considering an axino next-to-LSP (NLSP) as a coexisting dark matter particle contributing with a detectable signal in the $\gamma$-ray spectrum. The analysis is carried out in the framework of the $\mu\nu$SSM, which solves the $\mu$ problem reproducing simultaneously neutrino data only with the addition of right-handed neutrinos. We find that important regions of the parameter space can be tested by future MeV-GeV $\gamma$-ray telescopes through the line signal coming from the decay of the axino NLSP into photon-neutrino. In a special region, a double-line signal from axino NLSP and gravitino LSP is possible with both contributions detectable.

[53]  arXiv:1911.08660 (cross-list from physics.comp-ph) [pdf, other]

Title: Coupled MHD -- Hybrid Simulations of Space Plasmas

Authors: S. P. Moschou, I. V. Sokolov, O. Cohen, G. Toth, J. J. Drake, Z. Huang, C. Garraffo, J. D. Alvarado-Gómez, T. Gombosi

Comments: 13 pages, 3 figures, ASTRONUM 2019 refereed proceedings paper (in press)

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

Heliospheric plasmas require multi-scale and multi-physics considerations. On one hand, MHD codes are widely used for global simulations of the solar-terrestrial environments, but do not provide the most elaborate physical description of space plasmas. Hybrid codes, on the other hand, capture important physical processes, such as electric currents and effects of finite Larmor radius, but they can be used locally only, since the limitations in available computational resources do not allow for their use throughout a global computational domain. In the present work, we present a new coupled scheme which allows to switch blocks in the block-adaptive grids from fluid MHD to hybrid simulations, without modifying the self-consistent computation of the electromagnetic fields acting on fluids (in MHD simulation) or charged ion macroparticles (in hybrid simulation). In this way, the hybrid scheme can refine the description in specified regions of interest without compromising the efficiency of the global MHD code.

[54]  arXiv:1911.08900 (cross-list from physics.ins-det) [pdf, ps, other]

Title: NIEL Dose Analysis on triple and single junction InGaP/GaAs/Ge solar cells irradiated with electrons, protons and neutrons

Authors: Roberta Campesato, Carsten Baur, Mario Carta, Mariacristina Casale, Davide Chiesa, Massimo Gervasi, Enos Gombia, Erminio Greco, Aldo Kingma, Massimiliano Nastasi, Ezio Previtali, Pier Giorgio Rancoita, Davide Rozza, Emilio Santoro, Mauro Tacconi

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

Triple junction (InGaP/GaAs/Ge) and single junction (SJ) solar cells were irradiated with electrons, protons and neutrons. The degradation of remaining factors was analyzed as function of the induced Displacement Damage Dose (DDD) calculated by means of the SR-NIEL (Screened Relativistic Non Ionizing\ Energy Loss) approach. In particular, the aim of this work is to analyze the variation of the solar cells remaining factors due to neutron irradiation with respect to those previously obtained with electrons and protons. The current analysis confirms that the degradation of the $P_{max}$ electrical parameter is related by means of the usual semi-empirical expression to the displacement dose, independently of type of the incoming particle. $I_{sc}$ and $V_{oc}$ parameters were also measured as a function of the displacement damage dose. Furthermore, a DLTS analysis was carried out on diodes - with the same epitaxial structure as the middle sub-cell - irradiated with neutrons.

[55]  arXiv:1911.09050 (cross-list from hep-th) [pdf, ps, other]

Title: A Note on the Trans-Planckian Censorship Conjecture

Authors: A. Kehagias, A. Riotto

Comments: 8 pages

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

We discuss the trans-Planckian censorship conjecture in the framework of black hole thermodynamics. In particular, we consider black holes in de Sitter space and we show that the trans-Planckian censorship conjecture is a consequence of the fact that apparent horizons are always inside cosmic event horizons whenever they exist. In addition, we show that the Bekenstein and the Hubble entropy bounds for the entropy in a region of spacetime lead similarly to the trans-Planckian censorship conjecture. Finally, we show that the conjecture gives a bound on the number of e-folds relating the latter to the field theory cutoff and the number of species.

[56]  arXiv:1911.09061 (cross-list from cs.LG) [pdf, other]

Title: Challenges with Extreme Class-Imbalance and Temporal Coherence: A Study on Solar Flare Data

Authors: Azim Ahmadzadeh, Maxwell Hostetter, Berkay Aydin, Manolis K. Georgoulis, Dustin J. Kempton, Sushant S. Mahajan, Rafal A. Angryk

Comments: 9 pages, 9 figures, and 1 table, accepted in IEEE BigData 2019

Subjects: Machine Learning (cs.LG); Solar and Stellar Astrophysics (astro-ph.SR); Machine Learning (stat.ML)

In analyses of rare-events, regardless of the domain of application, class-imbalance issue is intrinsic. Although the challenges are known to data experts, their explicit impact on the analytic and the decisions made based on the findings are often overlooked. This is in particular prevalent in interdisciplinary research where the theoretical aspects are sometimes overshadowed by the challenges of the application. To show-case these undesirable impacts, we conduct a series of experiments on a recently created benchmark data, named Space Weather ANalytics for Solar Flares (SWAN-SF). This is a multivariate time series dataset of magnetic parameters of active regions. As a remedy for the imbalance issue, we study the impact of data manipulation (undersampling and oversampling) and model manipulation (using class weights). Furthermore, we bring to focus the auto-correlation of time series that is inherited from the use of sliding window for monitoring flares' history. Temporal coherence, as we call this phenomenon, invalidates the randomness assumption, thus impacting all sampling practices including different cross-validation techniques. We illustrate how failing to notice this concept could give an artificial boost in the forecast performance and result in misleading findings. Throughout this study we utilized Support Vector Machine as a classifier, and True Skill Statistics as a verification metric for comparison of experiments. We conclude our work by specifying the correct practice in each case, and we hope that this study could benefit researchers in other domains where time series of rare events are of interest.

[57]  arXiv:1911.09083 (cross-list from gr-qc) [pdf, other]

Title: Machine-learning non-stationary noise out of gravitational wave detectors

Authors: Gabriele Vajente, Yiwen Huang, Maximiliano Isi, Jenne C. Driggers, Jeffrey S. Kissel, Marek J. Szczepanczyk, Salvatore Vitale

Subjects: General Relativity and Quantum Cosmology (gr-qc); Instrumentation and Methods for Astrophysics (astro-ph.IM); Data Analysis, Statistics and Probability (physics.data-an); Instrumentation and Detectors (physics.ins-det)

Signal extraction out of background noise is a common challenge in high precision physics experiments, where the measurement output is often a continuous data stream. To improve the signal to noise ratio of the detection, witness sensors are often used to independently measure background noises and subtract them from the main signal. If the noise coupling is linear and stationary, optimal techniques already exist and are routinely implemented in many experiments. However, when the noise coupling is non-stationary, linear techniques often fail or are sub-optimal. Inspired by the properties of the background noise in gravitational wave detectors, this work develops a novel algorithm to efficiently characterize and remove non-stationary noise couplings, provided there exist witnesses of the noise source and of the modulation. In this work, the algorithm is described in its most general formulation, and its efficiency is demonstrated with examples from the data of the Advanced LIGO gravitational wave observatory, where we could obtain an improvement of the detector gravitational wave reach without introducing any bias on the source parameter estimation.

Replacements for Thu, 21 Nov 19

[58]  arXiv:1810.05976 (replaced) [pdf, other]

Title: Relativistic Electron Scattering and Big Bang Nucleosynthesis

Authors: Nishanth Sasankan, Atul Kedia, Motohiko Kusakabe, Grant J Mathews

Comments: 6 pages, 4 figures, this paper is superseded by arxiv:1911.07334

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

[59]  arXiv:1904.07510 (replaced) [pdf, ps, other]

Title: Constraining Chaplygin models using diffuse supernova neutrino background

Authors: Nan Yang, Junji Jia, Xionghui Liu, Hongbao Zhang

Comments: 12 pages, 2 figure and 4 tables; discussion part extended

Journal-ref: Physics of the Dark Universe 26, 100397(2019)

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

[60]  arXiv:1906.04060 (replaced) [pdf, other]

Title: CAFE2: an upgrade to the CAFE high-resolution spectrograph. Commissioning results and new public pipeline

Authors: J. Lillo-Box, J. Aceituno, S. Pedraz, G. Bergond, D. Galadí-Enríquez, M. Azzaro, B. Arroyo-Torres, A. Fernández-Martín, A. Guijarro, R. P. Hedrosa, I. Hermelo, F. Hoyo, P. Martín-Fernández

Comments: Accepted for publication in MNRAS. 15 pages, 14 figures and 4 tables. CAFExtractor is available through this Github link this https URL

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

[61]  arXiv:1906.07624 (replaced) [pdf, other]

Title: Acceleration in Friedmann cosmology with torsion

Authors: S. H. Pereira, R. de C. Lima, J. F. Jesus, R. F. L. Holanda

Comments: 17 pages, 6 figures

Journal-ref: Eur. Phys. J. C (2019) 79: 950

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

[62]  arXiv:1907.05879 (replaced) [pdf, ps, other]

Title: Resolving accretion flows in nearby active galactic nuclei with the Event Horizon Telescope

Authors: Bidisha Bandyopadhyay, Fu-Guo Xie, Neil M. Nagar, Dominik R. G. Schleicher, Venkatessh Ramakrishnan, Patricia Arévalo, Elena López, Yahelyn Diaz

Comments: 17 pages, 8 figures. Published in MNRAS

Journal-ref: Monthly Notices of the Royal Astronomical Society, Volume 490, Issue 4, p.4606-4621, 2019

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

[63]  arXiv:1907.05881 (replaced) [pdf, other]

Title: Euclid-era cosmology for everyone: Neural net assisted MCMC sampling for the joint 3x2 likelihood

Authors: Andrea Manrique-Yus, Elena Sellentin

Comments: Original version of the authors, as accepted by the referee(s)

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

[64]  arXiv:1907.06476 (replaced) [pdf, other]

Title: Would the Sun's photosphere be magnetised ?

Authors: Véronique Bommier

Comments: 11 pages, 4 figures, resubmitted to Astronomy and Astrophysics, Section Astrophysical Processes

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

[65]  arXiv:1907.10075 (replaced) [pdf, other]

Title: Neutron EDM constrains direct dark matter detection prospects

Authors: Manuel Drees, Rahul Mehra

Comments: 15 pages, 4 figures, 3 tables, v2: typos corrected; published version is shorter without any major changes

Journal-ref: Physics Letters B, Volume 799 (2019) 135039

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

[66]  arXiv:1908.04525 (replaced) [pdf, other]

Title: On the Origin of Solar Torsional Oscillations and Extended Solar Cycle

Authors: V.V. Pipin, A.G. Kosovichev

Comments: 22 pages, 10 Figures, v3, accepted in ApJ

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

[67]  arXiv:1909.02561 (replaced) [pdf, other]

Title: On the road to percent accuracy III: non-linear reaction of the matter power spectrum to massive neutrinos

Authors: Matteo Cataneo, J. D. Emberson, Derek Inman, Joachim Harnois-Deraps, Catherine Heymans

Comments: 7 pages, 3 figures; matches MNRAS accepted version

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

[68]  arXiv:1909.06944 (replaced) [pdf, ps, other]

Title: The equation of state and some key parameters of neutron stars: constraints from GW170817, the nuclear data and the low mass X-ray binary data

Authors: Jin-Liang Jiang, Shao-Peng Tang, Dong-Sheng Shao, Ming-Zhe Han, Yin-Jie Li, Yuan-Zhu Wang, Zhi-Ping Jin, Yi-Zhong Fan, Da-Ming Wei

Comments: 12 pages, 5 figures, 6 tables, ApJ published. Corrected the typo error between source frame masses and detector frame masses in section 2.5

Journal-ref: 2019, ApJ, 885, 39

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

[69]  arXiv:1909.11927 (replaced) [pdf, other]

Title: The Bayesian Asteroseismology data Modeling pipeline and its application to $\it K2$ data

Authors: Joel C. Zinn, Dennis Stello, Daniel Huber, Sanjib Sharma

Comments: Published in ApJ

Journal-ref: The Astrophysical Journal, Volume 884, Issue 2, article id. 107, 16 pp. (2019)

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

[70]  arXiv:1910.01750 (replaced) [pdf, other]

Title: PEXO: a global modeling framework for nanosecond timing, microsecond astrometry, and $μ$m/s radial velocities

Authors: Fabo Feng, Maksym Lisogorskyi, Hugh R. A. Jones, Sergei M. Kopeikin, R. Paul Butler, Guillem Anglada-Escude, Alan P. Boss

Comments: 54 pages, 2 tables, 19 figures; PEXO is available at this https URL

Journal-ref: The Astrophysical Journal Supplement Series 244.2 (2019) 39

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

[71]  arXiv:1910.02259 (replaced) [pdf]

Title: Rotational spectrum of isotopic methyl mercaptan, (13)CH3SH, in the laboratory and towards Sagittarius B2(N2)

Authors: V. V. Ilyushin, O. Zakharenko, F. Lewen, S. Schlemmer, E. A. Alekseev, M. Pogrebnyak, R. M. Lees, L.-H. Xu, A. Belloche, K. M. Menten, R. T. Garrod, H. S. P. Müller

Comments: 20 pages (with figures and tables); Can. J. Phys. (this https URL), accepted

Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA); Instrumentation and Methods for Astrophysics (astro-ph.IM); Atomic and Molecular Clusters (physics.atm-clus); Chemical Physics (physics.chem-ph)

[72]  arXiv:1910.05407 (replaced) [pdf]

Title: Distance and Evolutionary States of Supernova Remnant G18.9-1.1 and Candidate G28.6+0.0

Authors: S. Ranasinghe, D. Leahy, W. W. Tian

Comments: 11 pages, 6 figures

Journal-ref: Journal of High Energy Physics, Gravitation and Cosmology. 6(2020) 9-19

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

[73]  arXiv:1910.11050 (replaced) [pdf, ps, other]

Title: Surprises in the simultaneous X-ray and optical monitoring of pi Aqr

Authors: Yael Naze, G. Rauw (Univ. Liege), M. Smith (NOAO)

Comments: accepted for publication in A&A

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

[74]  arXiv:1910.11795 (replaced) [pdf, other]

Title: Supervised Machine Learning for Inter-comparison of Model Grids of Brown Dwarfs: Application to GJ 570D and the Epsilon Indi B Binary System

Authors: Maria Oreshenko, Daniel Kitzmann, Pablo Marquez-Neila, Matej Malik, Brendan P. Bowler, Adam J. Burgasser, Raphael Sznitman, Chloe E. Fisher, Kevin Heng

Comments: Accepted for publication in The Astronomical Journal

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

[75]  arXiv:1911.02701 (replaced) [pdf]

Title: Frequency of Coronal Mass Ejection Impacts with Early Terrestrial Planets and Exoplanets Around Active Solar-like Stars

Authors: Christina Kay, Vladimir S. Airapetian, Theresa Lüftinger, Oleg Kochukhov

Comments: 13 pages, 3 figures, accepted for publication in The Astrophysical Journal Letters

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

[76]  arXiv:1911.03736 (replaced) [pdf, other]

Title: Trans-Planckian Censorship and $k$-inflation

Authors: Wei-Chen Lin, William H. Kinney

Comments: 6 pages, 3 figures. (V2: typos corrected and references added.)

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

[77]  arXiv:1911.06333 (replaced) [pdf, other]

Title: The shape of relaxed galaxy clusters and the public release of a HST shape measurement code, pyRRG

Authors: David Harvey, Sut-Ieng Tam, Mathilde Jauzac, Richard Massey, Jason Rhodes

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

[78]  arXiv:1911.06826 (replaced) [pdf, other]

Title: Chemo-dynamics of barred galaxies in the Auriga simulations: The in-situ formation of the Milky Way bulge

Authors: F. Fragkoudi, R. J. J. Grand, R. Pakmor, G. Blázquez-Calero, I. Gargiulo, F. Gomez, F. Marinacci, A. Monachesi, M. K. Ness, I. Perez, P. Tissera, S. D. M. White

Comments: Corrected references in v2. Submitted to MNRAS

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

• New submissions
• Cross-lists
• Replacements