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New submissions for Mon, 10 Feb 20

[1]  arXiv:2002.02454 [pdf, other]

Title: Spatially-resolved UV diagnostics of AGN feedback: radiation pressure dominates in a prototypical quasar-driven superwind

Authors: Jean Somalwar, Sean D. Johnson, Jonathan Stern, Andy D. Goulding, Jenny E. Greene, Nadia L. Zakamska, Rachael M. Alexandroff, Hsiao-Wen Chen

Comments: Accepted to ApJ Letters. 11 pages, 5 figures and 1 table

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

Galactic-scale winds driven by active galactic nuclei (AGN) are often invoked to suppress star formation in galaxy evolution models, but the mechanisms driving these outflows are hotly debated. Two key AGN feedback models are (1) radiation pressure accelerating cool gas and (2) a hot outflowing wind entraining the ISM. Highly ionized emission-line diagnostics represent a powerful means of differentiating these scenarios because of their sensitivity to the expected compression of the ISM clouds by the hot wind. Here, we report the first spatially resolved UV emission spectroscopy of a prototypical (radio-quiet) quasar-driven superwind around the obscured quasar SDSSJ1356+1026 at z=0.123. We observe ratios of OVI/CIV, NV/CIV, and CIV/HeII that are remarkably similar for outflowing gas clouds <100 pc and ~10 kpc from the nucleus. Such similarity is expected for clouds with AGN radiation pressure dominated dynamics. Comparing the observed line emission to models of clouds in balance with radiation pressure and/or a hot wind, we rule out the presence of a dynamically important hot wind and constrain the ratio of hot gas pressure to radiation pressure to P_hot/P_rad<0.25 both at <100 pc and ~10 kpc from the nucleus. Moreover, the predictions of the radiation pressure confined cloud models that best fit observed UV line ratios are consistent with the observed diffuse X-ray spectrum. These results indicate that this AGN superwind is driven by radiation pressure or was driven by a hot wind that has since dissipated despite on-going AGN activity.

[2]  arXiv:2002.02455 [pdf, other]

Title: Planetary evolution with atmospheric photoevaporation I. Analytical derivation and numerical study of the evaporation valley and transition from super-Earths to sub-Neptunes

Authors: Christoph Mordasini

Comments: 32 pages, 16 figures. Accepted to A&A

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

Observations have revealed in the Kepler data a depleted region separating smaller super-Earths from larger sub-Neptunes. This can be explained as an evaporation valley between planets with and without H/He that is caused by atmospheric escape. First, we conduct numerical simulations of the evolution of close-in low-mass planets with H/He undergoing escape. Second, we develop an analytical model for the valley locus. We find that the bottom of the valley quantified by the radius of the largest stripped core $R_{\rm b}$ at a given orbital distance depends only weakly on post-formation H/He mass. The reason is that a high initial H/He mass means that there is more gas to evaporate, but also that the planet density is lower, increasing loss. Regarding stellar $L_{\rm XUV}$, $R_{\rm b}$ scales as $L_{\rm XUV}^{0.135}$. The same weak dependency applies to the efficiency factor $\varepsilon$ of energy-limited evaporation. As found numerically and analytically, $R_{\rm b}$ varies as function of orbital period $P$ for a constant $\varepsilon$ as $P^{-2 p_{\rm c}/3}\approx P^{-0.18}$ where $M \propto R^{p_{\rm c}}$ is the mass-radius relation of solid cores. $R_{\rm b}$ is about 1.7 $R_{\oplus}$ at a 10-day orbit for an Earth-like composition, increasing linearly with ice mass fraction. The numerical results are explained very well with the analytical model where complete evaporation occurs if the temporal integral over the stellar XUV irradiation absorbed by the planet is larger than binding energy of the envelope in the gravitational potential of the core. The weak dependency on primordial H/He mass, $L_{\rm XUV}$ and $\varepsilon$ explains why observationally the valley is visible, and why theoretically models find similar results. At the same time, given the large observed spread of $L_{\rm XUV}$, the dependency on it is still strong enough to explain why the valley is not completely empty.

[3]  arXiv:2002.02457 [pdf, other]

Title: Detection of PAH Absorption and Determination of the Mid-Infrared Diffuse Interstellar Extinction Curve from the Sightline Toward Cyg OB2-12

Authors: Brandon S. Hensley, B. T. Draine

Comments: Submitted to ApJ, comments welcome

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

The sightline toward the luminous blue hypergiant Cyg OB2-12 is widely used in studying interstellar dust on account of its large extinction ($A_V \simeq 10$ mag) and the fact that this extinction appears to be dominated by dust typical of the diffuse interstellar medium. We present a new analysis of archival ISO-SWS and Spitzer IRS observations of Cyg OB2-12 using a model of the emission from the star and its stellar wind to determine the total extinction $A_\lambda$ from 2.4--37 $\mu$m. In addition to the prominent 9.7 and 18 $\mu$m silicate features, we robustly detect absorption features associated with polycyclic aromatic hydrocarbons (PAHs), including the first identification of the 7.7 $\mu$m feature in absorption. The 3.3 $\mu$m aromatic feature is found to be much broader in absorption than is typically seen in emission. The 3.4 and 6.85 $\mu$m aliphatic hydrocarbon features are observed with relative strengths consistent with observation of these features on sightlines toward the Galactic Center. We identify and characterize more than sixty spectral lines in this wavelength range, which may be useful in constraining models of the star and its stellar wind. Based on this analysis, we present an extinction curve $A_\lambda/A_{2.2 \mu m}$ that extrapolates smoothly to determinations of the mean Galactic extinction curve at shorter wavelengths and to dust opacities inferred from emission at longer wavelengths, providing a new constraint on models of interstellar dust in the mid-infrared.

[4]  arXiv:2002.02461 [pdf, other]

Title: Convection with Misaligned Gravity and Rotation: Simulations and Rotating Mixing Length Theory

Authors: Laura K. Currie, Adrian J. Barker, Yoram Lithwick, Matthew K. Browning

Comments: 26 pages, 15 figures, accepted for publication in MNRAS

Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP); Fluid Dynamics (physics.flu-dyn)

We present numerical simulations, using two complementary setups, of rotating Boussinesq thermal convection in a three-dimensional Cartesian geometry with misaligned gravity and rotation vectors. This model represents a small region at a non-polar latitude in the convection zone of a star or planet. We investigate the effects of rotation on the bulk properties of convection at different latitudes, focusing on determining the relation between the heat flux and temperature gradient. We show that our results may be interpreted using rotating mixing length theory (RMLT). The simplest version of RMLT (due to Stevenson) considers the single mode that transports the most heat. This works reasonably well in explaining our results, but there is a systematic departure from these predictions (up to approximately $30\%$ in the temperature gradient) at mid-latitudes. We develop a more detailed treatment of RMLT that includes the transport afforded by multiple modes, and we show that this accounts for most of the systematic differences. We also show that convectively-generated zonal flows and meridional circulations are produced in our simulations, and that their properties depend strongly on the dimensions of the box. These flows also affect the heat transport, contributing to departures from RMLT at some latitudes. However, we find the theoretical predictions of the multi-mode theory for the mid-layer temperature gradient, the root-mean-square (RMS) vertical velocity, the RMS temperature fluctuation, and the spatial spectrum of the heat transport at different latitudes, are all in reasonably good agreement with our numerical results when zonal flows are small.

[5]  arXiv:2002.02462 [pdf, other]

Title: Cosmic-Ray Driven Outflows to Mpc Scales from $L_{\ast}$ Galaxies

Authors: Philip F. Hopkins (Caltech), T. K. Chan (Durham), Suoqing Ji (Caltech), Cameron Hummels (Caltech), Dusan Keres (UCSD), Eliot Quataert (Berkeley), Claude-Andre Faucher-Giguere (Northwestern)

Comments: 23 pages, 20 figures, submitted to MNRAS. Comments welcome. Animations in CGM/IGM section at this http URL

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

We study the effects of cosmic rays (CRs) on outflows from star-forming galaxies in the circum and inter-galactic medium (CGM/IGM), in high-resolution, fully-cosmological FIRE-2 simulations (accounting for mechanical and radiative stellar feedback, magnetic fields, anisotropic conduction/viscosity/CR diffusion and streaming, and CR losses). We showed previously that massive ($M_{\rm halo}\gtrsim 10^{11}\,M_{\odot}$), low-redshift ($z\lesssim 1-2$) halos can have CR pressure dominate over thermal CGM pressure and balance gravity, giving rise to a cooler CGM with an equilibrium density profile. This dramatically alters outflows. Absent CRs, high gas thermal pressure in massive halos "traps" galactic outflows near the disk, so they recycle. With CRs injected in supernovae as modeled here, the low-pressure halo allows "escape" and CR pressure gradients continuously accelerate this material well into the IGM in "fast" outflows, while lower-density gas at large radii is accelerated in-situ into "slow" outflows that extend to $>$Mpc scales. CGM/IGM outflow morphologies are radically altered: they become mostly volume-filling (with inflow in a thin mid-plane layer) and coherently biconical from the disk to $>$Mpc. The CR-driven outflows are primarily cool ($T\sim10^{5}\,$K) and low-velocity. All of these effects weaken and eventually vanish at lower halo masses ($\lesssim 10^{11}\,M_{\odot}$) or higher redshifts ($z\gtrsim 1-2$), reflecting the ratio of CR to thermal+gravitational pressure in the outer halo. We present a simple analytic model which explains all of the above phenomena.

[6]  arXiv:2002.02464 [pdf, other]

Title: Cosmology with quasars: predictions for eROSITA from a quasar Hubble diagram

Authors: Elisabeta Lusso (UniFI/INAF-Arcetri)

Comments: 9 pages, 2 figures, submitted to Frontiers in Astronomy and Space Sciences (research topic: Quasars in Cosmology). Abstract abridged. Amended version after first referees' reports. Comments welcome

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

Our group has developed a technique that makes use of the observed non-linear relation between the ultraviolet and the X-ray luminosity in quasars to provide an independent measurement of their distances, thus turning quasars into standardizable candles. This technique, at present, it is mostly based upon quasar samples with data from public catalogues both in the X-rays and in the optical/ultraviolet and extends the Hubble diagram of supernovae to a redshift range still poorly explored (z>2). From the X-ray perspective, we are now on the eve of a major change, as the upcoming mission eROSITA is going to provide us with up to ~3 millions of active galactic nuclei across the entire sky. Here we present predictions for constraining cosmological parameters such as the amount of dark matter ($\Omega_{\rm m}$), dark energy ($\Omega_\Lambda$) and the evolution of the equation of state of dark energy ($w$) through the Hubble diagram of quasars, based on the 4-year eROSITA all-sky survey. Our simulations show that the eROSITA quasars, complemented by redshift and broad-band photometric information, will supply the largest quasar sample at z<2, but with very few objects available for cosmology at higher redshifts that survives the cut for the Malmquist bias, as eROSITA will sample the brighter end of the X-ray luminosity function. The power of the quasar Hubble diagram for precision cosmology lies in the high-redshift regime, where quasars can be observed up to redshift ~7.5, essential to discriminate amongst different model extrapolations. Therefore, to be competitive for cosmology, the eROSITA quasar Hubble diagram must be complemented with the already available quasar samples and dedicated (deep) large programmes at redshift z>3.

[7]  arXiv:2002.02466 [pdf, other]

Title: Cross-correlating galaxy catalogs and gravitational waves: a tomographic approach

Authors: F. Calore, A. Cuoco, T. Regimbau, S. Sachdev, P. D. Serpico

Comments: 13 pages, 11 multi-panel figures

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

Unveiling the origin of the coalescing binaries detected via gravitational waves (GW) is challenging, notably if no multi-wavelength counterpart is detected. One important quantity for diagnostics is their distribution with respect to the large scale structures of the universe, as encoded, for instance, in their (linear) biases. We discuss the perspectives of inferring these quantities via the cross-correlation of galaxy catalogs with mock GW ones, using both existing and forthcoming galaxy catalogs and using realistic Monte Carlo simulations of GW events. We find that the bias should be marginally detectable for a 10-year data taking of current generation detectors at design sensitivity, at least for binary neutron star mergers. The forthcoming five detector network would allow for a firmer detection of this signal and, in combination with future cosmological surveys, would also permit the detection of the coalescing black hole bias. Such a measurement may also unveil, for instance, a primordial origin of coalescing black holes. To attain this goal, we find that it is crucial to adopt a tomographic approach and to reach a sufficiently accurate localization of GW events. The depth of forthcoming surveys will be fully exploited by third generation GW detectors, which will allow one to perform precision studies of the coalescing black holes bias and attain rather advanced model discrimination capabilities, at a few percent level.

[8]  arXiv:2002.02467 [pdf, other]

Title: Hydrodynamic Response of the Intergalactic Medium to Reionization

Authors: Anson D'Aloisio, Matthew McQuinn, Hy Trac, Christopher Cain, Andrei Mesinger

Comments: Submitted to ApJ

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

The intergalactic medium is expected to clump on scales down to $10^4-10^8$ M$_{\odot}$ before the onset of reionization. The impact of these small-scale structures on reionization is poorly understood despite the modern understanding that gas clumpiness limits the growth of H II regions. We use a suite of radiation-hydrodynamics simulations that capture the $\sim 10^4$ M$_{\odot}$ Jeans mass of unheated gas to study density fluctuations during reionization. Our simulations track the complex ionization and hydrodynamical response of gas in the wake of ionization fronts. The clumping factor of ionized gas (proportional to the recombination rate) rises to a peak value of $5-20$ approximately $\Delta t = 10$ Myr after ionization front passage, depending on the incident intensity, redshift, and degree to which the gas had been pre-heated by the first X-ray sources. The clumping factor reaches its relaxed value of $\approx 3$ by $\Delta t = 300$ Myr. The mean free path of Lyman-limit photons evolves in unison, being up to several times shorter in un-relaxed, recently reionized regions compared to those that were reionized much earlier. Assessing the impact of this response on the global reionizaton process, we find that un-relaxed gaseous structures boost the total number of recombinations by $\approx 50$ % and lead to spatial fluctuations in the mean free path that persist appreciably for several hundred million years after the completion of reionization.

[9]  arXiv:2002.02468 [pdf, other]

Title: Long-term NIR Variability in the UKIDSS Ultra Deep Survey: a new probe of AGN activity at high redshift

Authors: E. Elmer, O. Almaini, M. Merrifield, W. G. Hartley, D. T. Maltby, A. Lawrence, I. Botti, P. Hirst

Comments: 12 pages, 18 figures, accepted for publication in MNRAS

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

We present the first attempt to select AGN using long-term NIR variability. By analysing the K-band light curves of all the galaxies in the UKIDSS Ultra Deep Survey, the deepest NIR survey over ~1 sq degree, we have isolated 393 variable AGN candidates. A comparison to other selection techniques shows that only half of the variable sources are also selected using either deep Chandra X-ray imaging or IRAC colour selection, suggesting that using NIR variability can locate AGN that are missed by more standard selection techniques. In particular, we find that long-term NIR variability identifies AGN at low luminosities and in host galaxies with low stellar masses, many of which appear relatively X-ray quiet.

[10]  arXiv:2002.02469 [pdf, other]

Title: Prevalence of Complex Organic Molecules in Starless and Prestellar Cores within the Taurus Molecular Cloud

Authors: Samantha Scibelli, Yancy Shirley

Comments: Accepted to ApJ. 23 pages, 14 Figures, 9 Tables

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

The detection of complex organic molecules (COMs) toward dense, collapsing prestellar cores has sparked interest in the fields of astrochemistry and astrobiology, yet the mechanisms for COM formation are still debated. It was originally believed that COMs initially form in ices which are then irradiated by UV radiation from the surrounding interstellar radiation field as well as forming protostars and subsequently photodesorbed into the gas-phase. However, starless and prestellar cores do not have internal protostars to heat-up and sublimate the ices. Alternative models using chemical energy have been developed to explain the desorption of COMs, yet in order to test these models robust measurements of COM abundances are needed toward representative samples of cores. We've conducted a large-sample survey of 31 starless and prestellar cores in the Taurus Molecular Cloud, detecting methanol (CH$_3$OH) in 100$\%$ of the cores targeted and acetaldehyde (CH$_3$CHO) in 70$\%$. At least two transition lines of each molecule were measured, allowing us to place tight constraints on excitation temperature, column density and abundance. Additional mapping of methanol revealed extended emission, detected down to A$_\mathrm{V}$ as low as $\sim$ 3 mag. We find complex organic molecules are detectable in the gas-phase and are being formed early, at least hundreds of thousands of years prior to star and planet formation. The precursor molecule, CH$_3$OH, may be chemically linked to the more complex CH$_3$CHO, however higher spatial resolution maps are needed to further test chemical models.

[11]  arXiv:2002.02473 [pdf, other]

Title: A Novel Survey for Young Substellar Objects with the W-band filter II. The Coolest and Lowest Mass Members of the Serpens-South Star-forming Region

Authors: Jessy Jose, Beth A. Biller, Loıc Albert, Sophie Dubber, Katelyn Allers, Gregory J. Herczeg, Michael C. Liu, Samuel Pearson, Bhavana Lalchand, Wen-Ping Chen, Mickael Bonnefoy, Etienne Artigau, Philippe Delorme, Po-shih Chiang, Zhoujian Zhang, Yumiko Oasa

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

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

Given its relative proximity (~430 pc), compact size (< 20'), young age (~ 0.5 Myr) and rich number of young stellar objects, the Serpens-South star forming region is a promising site for studying young sub-stellar objects, yet the low-mass members of this region remain largely undiscovered. In this paper we report on a deep photometric survey using a custom 1.45 um filter (W-band), as well as standard J and H near-IR filters, in order to identify candidate low-mass young brown-dwarfs in the Serpens-South region. We constructed a reddening-insensitive index (Q) by combining J, H and W-band photometry for survey objects, in order to identify candidate low-mass members of Serpens based on the strength of the water absorption feature at 1.45 um in the atmospheres of mid-M and later objects. We then conducted spectroscopic follow up to confirm youth and spectral type for our candidates. This is the first survey to identify the very low-mass and coolest members of Serpens-South. We identify 4 low-mass candidate Serpens members, which all display IR excess emission, indicating the likely presence of circumstellar disks around them. One of the four candidate low-mass members in our list, SERP182918-020245, exhibits Pa_beta and Br_gamma emission features, confirming its youth and ongoing magnetospheric accretion. Our new candidate members have spectral types >M4 and are the coolest and lowest mass candidate members yet identified in Serpens-South.

[12]  arXiv:2002.02486 [pdf, other]

Title: Calibrating GONG Magnetograms with End-to-end Instrument Simulation III: Comparison, Calibration, and Results

Authors: Joseph Plowman, Thomas Berger

Comments: Submitted to Solar Physics, third of three papers (the other two are arXiv submissions 3034511 and 3034641)

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

This is the last of three papers describing an `absolute' calibration of the GONG magnetograph using and end-to-end simulation of its measurement process. The simulation begins with a MURaM 3D MHD datacube and ends with a `synthetic magnetogram' of the corresponding magnetic field values as they would be observed by GONG. We determine a calibration by comparing the synthetic magnetic field measurements with the MURaM magnetic field values that produced them. The previous two papers have described the GONG measurement process (both instrument and data processing), our simulation of it, and the theory of magnetogram comparison and calibration. In this paper, we address some final points on calibration, combine all of this work into a set of calibration curves, and consider the results. We also review the results of the previous two papers for locality of reference. Our calibration indicates that GONG magnetograms underestimate weak flux by a factor of over 2 near disk center, but that factor decreases to about 1 as the line-of-sight approaches the limb. A preliminary investigation of the generalizability of these results suggests other instruments will be affected in a similar way. We also find that some differences in previous magnetograph comparisons are artifacts of instrumental resolution which do not reflect an intrinsic calibration difference, and the measurements are more similar than sometimes thought. These results are directly applicable to question of solar wind prediction model accuracies, particularly in the search for the cause of the common discrepancy between predicted solar wind magnetic flux at 1 AU and values measured in situ by current satellite missions.

[13]  arXiv:2002.02489 [pdf, other]

Title: Calibrating GONG Magnetograms with End-to-end Instrument Simulation I: Background, the GONG Instrument, and End-to-end Simulation

Authors: Joseph Plowman, Thomas Berger

Comments: Submitted to Solar Physics, first of three papers (the other two are arXiv submissions 3034641 and 3034660)

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

This is the first of three papers describing an `absolute' calibration of the GONG magnetograph using an end-to-end simulation of its measurement process. The input to this simulation is a MURaM 3D MHD photospheric simulation and the output is the corresponding set of simulated data numbers which would be recorded by the GONG detectors. These simulated data numbers are then used to produce `synthetic magnetograms' which can be compared with the simulation inputs. This paper describes the GONG instrument, the MURaM datacube, our instrument simulator, and calculation of synthetic magnetograms, setting the stage for the subsequent two papers. These will first lay groundwork for calibration (and magnetogram comparison in general), then apply them to calibration of GONG using the simulation results.

[14]  arXiv:2002.02490 [pdf, other]

Title: Calibrating GONG Magnetograms with End-to-end Instrument Simulation II: Theory of Calibration

Authors: Joseph Plowman, Thomas Berger

Comments: Submitted to Solar Physics, second of three papers (the other two are arXiv submissions 3034511 and 3034660)

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

This is the second of three papers describing an `absolute' calibration of the GONG magnetograph using an end-to-end simulation of its measurement process. In the first paper, we described the GONG instrument and our `end-to-end' simulation of its measurement process. In this paper, we consider the theory of calibration, and magnetograph comparison in general, identifying some of the significant issues and pitfalls. The calibration of a magnetograph is a function of whether or not it preserves flux, independent of its spatial resolution. However, we find that the one-dimensional comparison methods most often used for magnetograph calibration and comparison will show dramatic differences between two magnetograms with differing spatial resolution, even if they both preserve flux. Some of the apparent disagreement between magnetograms found in the literature are likely a result of these instrumental resolution differences rather than any intrinsic calibration differences. To avoid them, spatial resolution must be carefully matched prior to comparing magnetograms or making calibration curves. In the third paper, we apply the lessons learned here to absolute calibration of GONG using our `end-to-end' measurement simulation.

[15]  arXiv:2002.02498 [pdf, other]

Title: The Structure of Tidal Disruption Event Host Galaxies on Scales of Tens to Thousands of Parsecs

Authors: K. Decker French (1), Iair Arcavi (2,3), Ann I. Zabludoff (4), Nicholas Stone (5), Daichi Hiramatsu (6,7), Sjoert van Velzen (8,9), Curtis McCully (6,7), Ning Jiang (10) ((1) Carnegie Observatories (2) Tel Aviv University (3) CIFAR Azrieli Global Scholars program (4) University of Arizona (5) Hebrew University (6) University of California Santa Barbara (7) Las Cumbres Observatory (8) New York University (9) University of Maryland (10) University of Science and Technology of China)

Comments: Accepted for publication in ApJ. 22 pages, 12 figures

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

We explore the galaxy structure of four tidal disruption event (TDE) host galaxies on 30 pc to kpc scales using HST WFC3 multi-band imaging. The star formation histories of these hosts are diverse, including one post-starburst galaxy (ASASSN-14li), two hosts with recent weak starbursts (ASASSN-14ae and iPTF15af), and one early type (PTF09ge). Compared to early type galaxies of similar stellar masses, the TDE hosts have higher central surface brightnesses and stellar mass surface densities on 30-100 pc scales. The TDE hosts do not show the large, kpc-scale tidal disruptions seen in some post-starburst galaxies; the hosts have low morphological asymmetries similar to those of early type galaxies. The lack of strong asymmetries are inconsistent with a recent major (~1:1 mass) merger, although minor ($\lesssim$1:3) mergers are possible. Given the time elapsed since the end of the starbursts in the three post-burst TDE hosts and the constraints on the merger mass ratios, it is unlikely that a bound supermassive black hole binary (SMBHB) has had time to coalesce. The TDE hosts have low central (<140 pc) ellipticities compared to early type galaxies. The low central ellipticities disfavor a strong radial anisotropy as the cause for the enhanced TDE rate, although we cannot rule out eccentric disks at the scale of the black hole gravitational radius of influence (~1 pc). These observations suggest that the high central stellar densities are a more important driver than SMBHBs or radial anisotropies in increasing the TDE rate in galaxies with recent starbursts.

[16]  arXiv:2002.02499 [pdf, other]

Title: Optical/near-infrared observations of the Fried Egg Nebula: Multiple shell ejections on a 100 yr timescale from a massive yellow hypergiant

Authors: E. Koumpia, R. D. Oudmaijer, V. Graham, G. Banyard, J. H. Black, C. Wichittanakom, K. M. Ababakr, W.-J. de Wit, F. Millour, E. Lagadec, S. Muller, N. L. J. Cox, A. Zijlstra, H. van Winckel, M. Hillen, R. Szczerba, J. S. Vink, S. H. J. Wallstrom

Comments: 26 pages, 22 Figures, 6 tables, accepted for publication in A&A. Original abstract will be available after publication

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

Context. The fate of a massive star during the latest stages of its evolution is highly dependent on its mass-loss rate/geometry and therefore knowing the geometry of the circumstellar material close to the star and its surroundings is crucial. Aims. We aim to study the nature (i.e. geometry, rates) of mass-loss episodes. In this context, yellow hypergiants are great targets. Methods. We analyse a large set of optical/near-infrared data, in spectroscopic and photometric (X-shooter/VLT), spectropolarimetric (ISIS/WHT), and interferometric GRAVITY-AMBER/VLTI) modes, toward the yellow hypergiant IRAS 17163-3907. We present the first model-independent reconstructed images of IRAS 17163-3907 at these wavelengths at milli-arcsecond scales. Lastly, we apply a 2D radiative transfer model to fit the dereddened photometry and the radial profiles of published VISIR images at 8.59 {\mu}m, 11.85 {\mu}m and 12.81 {\mu}m simultaneously, adopting the revised Gaia distance (DR2). Results. The interferometric observables around 2 {\mu}m show that the Br{\gamma} emission is more extended and asymmetric than the Na i and the continuum emission. In addition to the two known shells surrounding IRAS 17163-3907 we report on the existence of a third hot inner shell with a maximum dynamical age of only 30 yr. Conclusions. The interpretation of the presence of Na i emission at closer distances to the star compared to Br{\gamma} has been a challenge in various studies. We argue that the presence of a pseudophotosphere is not needed, but it is rather an optical depth effect. The three observed distinct mass-loss episodes are characterised by different mass-loss rates and can inform the theories on mass-loss mechanisms, which is a topic still under debate. We discuss these in the context of photospheric pulsations and wind bi-stability mechanisms.

[17]  arXiv:2002.02546 [pdf, other]

Title: Convective boundary mixing in low- and intermediate-mass stars I.Core properties from pressure-mode asteroseismology

Authors: George C Angelou, Earl P. Bellinger, Saskia Hekker, Yvonne Elsworth, Sarbani Basu, Achim Weiss

Comments: 20 Pages, 9 Figures, 4 Tables and supplementary material. Accepted for publication in MNRAS

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

Convective boundary mixing (CBM) is ubiquitous in stellar evolution. It is a necessary ingredient in the models in order to match observational constraints from clusters, binaries and single stars alike. We compute `effective overshoot' measures that reflect the extent of mixing and which can differ significantly from the input overshoot values set in the stellar evolution codes. We use constraints from pressure modes to infer the CBM properties of Kepler and CoRoT main-sequence and subgiant oscillators, as well as in two radial velocity targets (Procyon A and $\alpha$ Cen A). Collectively these targets allow us to identify how measurement precision, stellar spectral type, and overshoot implementation impact the asteroseismic solution. With these new measures we find that the `effective overshoot' for most stars is in line with physical expectations and calibrations from binaries and clusters. However, two F-stars in the CoRoT field (HD 49933 and HD 181906) still necessitate high overshoot in the models. Due to short mode lifetimes, mode identification can be difficult in these stars. We demonstrate that an incongruence between the radial and non-radial modes drives the asteroseismic solution to extreme structures with highly-efficient CBM as an inevitable outcome. Understanding the cause of seemingly anomalous physics for such stars is vital for inferring accurate stellar parameters from TESS data with comparable timeseries length.

[18]  arXiv:2002.02549 [pdf]

Title: The Impact of Planetary Rotation Rate on the Reflectance and Thermal Emission Spectrum of Terrestrial Exoplanets Around Sun-like Stars

Authors: Scott D. Guzewich, Jacob Lustig-Yaeger, Christopher Evan Davis, Ravi Kumar Kopparapu, Michael J. Way, Victoria S. Meadows

Comments: Resubmitted to The Astrophysical Journal following review and revision

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

Robust atmospheric and radiative transfer modeling will be required to properly interpret reflected light and thermal emission spectra of terrestrial exoplanets. This will break degeneracies between the numerous atmospheric, planetary, and stellar factors that drive planetary climate. Here we simulate the climates of Earth-like worlds around the Sun with increasingly slow rotation periods, from Earth-like to fully Sun-synchronous, using the ROCKE-3D general circulation model. We then provide these results as input to the Spectral Planet Model (SPM), which employs the SMART radiative transfer model to simulate the spectra of a planet as it would be observed from a future space-based telescope. We find that the primary observable effects of slowing planetary rotation rate are the altered cloud distributions, altitudes, and opacities which subsequently drive many changes to the spectra by altering the absorption band depths of biologically-relevant gas species (e.g., H2O, O2, and O3). We also identify a potentially diagnostic feature of synchronously rotating worlds in mid-infrared H2O absorption/emission lines.

[19]  arXiv:2002.02553 [pdf, other]

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

Authors: Huan Yang, Yuan-Chuan Zou

Comments: 11 pages, 4 figures

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

FRB 180916.J0158+65 has been found to repeatedly emit fast radio bursts with the period in roughly 16 days. We propose that such periodicity comes from orbital-induced, spin precession of the emitter, which is possibly a neutron star. Depending on the mass of the companion, the binary period ranges from several hundreds to thousands of seconds. Such tight binary has a relatively short lifetime, which does not likely come from the gravitational decay of a wide binary. We comment on the relation to GW 190425 and the possibility in LISA and LIGO detections.

[20]  arXiv:2002.02558 [pdf, other]

Title: Wolf-Rayet stars in M81 using GTC/OSIRIS: 7 new detections, analysis and classification of the full sample

Authors: V.M.A. Gómez-González, Y.D. Mayya, D. Rosa-González, L. H. Rodríguez-Merino, J.A. Toalá, C. Alvarez

Comments: 15 pages, 7 figures, 6 tables; accepted to MNRAS

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

We report the detection of 7 new Wolf-Rayet (WR) star locations in M81 using the Multi-Object Spectrograph of the OSIRIS instrument at Gran Telescopio Canarias. These detections are the result of a follow-up of an earlier study using the same instrumental set-up that resulted in the detection of 14 WR locations. We analyse the entire sample of 21 spectra to classify them to one of the known WR sub-types using template spectra of WR stars in the Large Magellanic Cloud (LMC), with similar metallicity to M81. Taking into consideration the dispersion in the strengths of the bumps for a given WR sub-type, we found that 19 of the 21 locations correspond to individual stars, including all the 7 new detections, of sub-types: WNL, WNE, WCE and the transitional WN/C. None of the detections correspond to WCL or WO types. The positions of these stars in the red bump vs blue bump luminosity diagram agrees well with an evolutionary path according to the Conti scenario. Based on this, we propose this diagram as a straightforward tool for spectral classification of extragalactic WR sources. The detection of individual WR stars in M81, which is at a distance of 3.6 Mpc, opens up a new environment for testing the massive star evolutionary models.

[21]  arXiv:2002.02570 [pdf, other]

Title: AGB winds in interacting binary stars

Authors: Luis C. Bermúdez-Bustamante, G. García-Segura, W. Steffen, L. Sabin

Comments: 13 pages, 17 figures, accepted for publication in MNRAS

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

We perform numerical simulations to investigate the stellar wind from interacting binary stars. Our aim is to find analytical formulae describing the outflow structure. In each binary system the more massive star is in the asymptotic giant branch and its wind is driven by a combination of pulsations in the stellar surface layers and radiation pressure on dust, while the less massive star is in the main sequence. Time averages of density and outflow velocity of the stellar wind are calculated and plotted as profiles against distance from the centre of mass and colatitude angle. We find that mass is lost mainly through the outer Lagrangian point L2. The resultant outflow develops into a spiral at low distances from the binary. The outflowing spiral is quickly smoothed out by shocks and becomes an excretion disk at larger distances. This leads to the formation of an outflow structure with an equatorial density excess, which is greater in binaries with smaller orbital separation. The pole-to-equator density ratio reaches a maximum value of $\sim10^5$ at Roche-Lobe Overflow state. We also find that the gas stream leaving L2 does not form a circumbinary ring for stellar mass ratios above 0.78, when radiation pressure on dust is taken into account. Analytical formulae are obtained by curve fitting the 2-dimensional, azimuthally averaged density and outflow velocity profiles. The formulae can be used in future studies to setup the initial outflow structure in hydrodynamic simulations of common-envelope evolution and formation of planetary nebulae.

[22]  arXiv:2002.02573 [pdf, other]

Title: Occurrence Rates of Planets Orbiting M Stars: Applying ABC to Kepler DR25, Gaia DR2, and 2MASS Data

Authors: Danley C. Hsu, Eric B. Ford, Ryan Terrien

Comments: 12 pages, 3 figures; submitted to MNRAS

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

We present robust planet occurrence rates for Kepler planet candidates around M stars for planet radii $R_p = 0.5-4~\textrm{R}_\oplus$ and orbital periods $P = 0.5-256$ days using the approximate Bayesian computation (ABC) technique. This work incorporates the final Kepler DR25 planet candidate catalog and data products and augment them with updated stellar properties using Gaia DR2 and 2MASS PSC. We analyze a clean sample of $1,530$ Kepler targets that host $89$ associated planet candidates. These early M-dwarfs and late K-dwarfs were selected from cross-referenced targets using several photometric quality flags from Gaia DR2 and color-magnitude cuts using 2MASS magnitudes. We identify a habitable zone occurrence rate of $f_{\textrm{HZ}} = 0.38^{+0.04}_{-0.05}$ for planets with $0.75-1.5$ R$_\oplus$ size. We caution that occurrence rate estimates for Kepler's M stars are sensitive to the choice of prior due to the small sample of target stars and planet candidates. For example, we find an occurrence rate of $8.9^{+1.2}_{-0.9}$ or $4.8^{+0.7}_{-0.6}$ planets per M-dwarf (integrating over $R_p = 0.5-4~\textrm{R}_\oplus$ and $P = 0.5-256$ days) for our two choices of prior. These occurrence rates are greater than those for FGK-dwarf target when compared at the same range of orbital periods, but similar to occurrence rates when computed as a function of equivalent stellar insolation. This suggests that stellar irradiance has a significant and possibly dominant role in planet formation processes regardless of spectral type. Combining our result with recent studies of exoplanet architectures indicates that most, and potentially all, early-M dwarfs harbor planetary systems.

[23]  arXiv:2002.02575 [pdf, other]

Title: Deep multi-redshift limits on Epoch of Reionisation 21cm Power Spectra from Four Seasons of Murchison Widefield Array Observations

Authors: Cathryn M. Trott, C. H. Jordan, S. Midgley, N. Barry, B. Greig, B. Pindor, J. H. Cook, G. Sleap, S. J. Tingay, D. Ung, P. Hancock, A. Williams, J. Bowman, R. Byrne, A. Chokshi, B. J. Hazelton, K. Hasegawa, D. Jacobs, R. C. Joseph, W. Li, J.L.B Line, C. Lynch, B. McKinley, D. A. Mitchell, M. F. Morales, M. Ouchi, J. C. Pober, M. Rahimi, K. Takahashi, R. B. Wayth, R. L. Webster, M. Wilensky, J. S. B. Wyithe, S. Yoshiura, Z. Zhang, Q. Zheng

Comments: 19 pages, 29 figures, accepted for publication in Monthly Notices of the Royal Astronomical Society

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

We compute the spherically-averaged power spectrum from four seasons of data obtained for the Epoch of Reionisation (EoR) project observed with the Murchison Widefield Array (MWA). We measure the EoR power spectrum over $k= 0.07-3.0~h$Mpc$^{-1}$ at redshifts $z=6.5-8.7$. The largest aggregation of 110 hours on EoR0 high-band (3,340 observations), yields a lowest measurement of (43~mK)$^2$ = 1.8$\times$10$^3$ mK$^2$ at $k$=0.14~$h$Mpc$^{-1}$ and $z=6.5$ (2$\sigma$ thermal noise plus sample variance). Using the Real-Time System to calibrate and the CHIPS pipeline to estimate power spectra, we select the best observations from the central five pointings within the 2013--2016 observing seasons, observing three independent fields and in two frequency bands. This yields 13,591 2-minute snapshots (453 hours), based on a quality assurance metric that measures ionospheric activity. We perform another cut to remove poorly-calibrated data, based on power in the foreground-dominated and EoR-dominated regions of the two-dimensional power spectrum, reducing the set to 12,569 observations (419 hours). These data are processed in groups of 20 observations, to retain the capacity to identify poor data, and used to analyse the evolution and structure of the data over field, frequency, and data quality. We subsequently choose the cleanest 8,935 observations (298 hours of data) to form integrated power spectra over the different fields, pointings and redshift ranges.

[24]  arXiv:2002.02606 [pdf, other]

Title: The continuing search for evidence of tidal orbital decay of hot Jupiters

Authors: Kishore C. Patra, Joshua N. Winn, Matthew J. Holman, Michael Gillon, Artem Burdanov, Emmanuel Jehin, Laetitia Delrez, Francisco J. Pozuelos, Khalid Barkaoui, Zouhair Benkhaldoun, Norio Narita, Akihiko Fukui, Nobuhiko Kusakabe, Kiyoe Kawauchi, Yuka Terada, L.G. Bouma, Nevin N. Weinberg, Madelyn Broome

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

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

Many of the known hot Jupiters are formally unstable to tidal orbital decay. The only hot Jupiter for which orbital decay has been directly detected is WASP-12, for which transit timing measurements spanning more than a decade have revealed that the orbital period is decreasing at a rate of $dP/dt\approx 10^{-9}$, corresponding to a reduced tidal quality factor of about $2\times 10^5$. Here, we present a compilation of transit-timing data for WASP-12 and eleven other systems which are especially favorable for detecting orbital decay: KELT-16; WASP-18, 19, 43, 72, 103, 114, and 122; HAT-P-23; HATS-18; and OGLE-TR-56. For most of these systems we present new data that extend the time baseline over which observations have been performed. None of the systems besides WASP-12 displays convincing evidence for period changes, with typical upper limits on $dP/dt$ on the order of $10^{-9}$ or $10^{-10}$, and lower limits on the reduced tidal quality factor on the order of $10^5$. One possible exception is WASP-19, which shows a statistically significant trend, although it may be a spurious effect of starspot activity. Further observations are encouraged.

[25]  arXiv:2002.02619 [pdf, other]

Title: Modeling Magnetohydrodynamic Equilibrium in Magnetars with Applications to Continuous Gravitational Wave Production

Authors: Samuel G. Frederick, Michelle P. Kuchera, Kristen L. Thompson

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

Possessing the strongest magnetic fields in the Universe, magnetars mark an extremum of physical phenomena. The strength of their magnetic fields is sufficient to deform the shape of the stellar body, and when the rotational and magnetic axes are not aligned, these deformations lead to the production of gravitational waves (GWs) via a time-varying quadrupole moment. Such gravitational radiation differs from signals presently detectable by the Laser Interferometer Gravitational-Wave Observatory. These signals are continuous rather than the momentary 'chirp' waveforms produced by binary systems during the phases of inspiral, merger, and ringdown. We evaluate the sensitivity requirements of future iterations of GW detectors to continuous GW signals resulting from magnetars. Here, we construct a computational model for magnetar stellar structure with strong internal magnetic fields. We implement an n = 1 polytropic equation of state (EOS) and adopt a mixed poloidal and toroidal magnetic field model constrained by the choice of EOS. We utilize fiducial values for magnetar magnetic field strength and various stellar physical attributes. Via computational simulation, we measure the deformation of magnetar stellar structure to determine upper bounds on the strength of continuous GWs formed as a result of these deformations inducing non-axisymmetric rotation. We compute predictions of upper limit GW strain values for sources in the McGill Magnetar Catalog, an index of all detected magnetars.

[26]  arXiv:2002.02670 [pdf, other]

Title: Calibration of a star formation and feedback model for cosmological simulations with Enzo

Authors: Boon Kiat Oh, Britton D. Smith, John A. Peacock, Sadegh Khochfar

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

We present results from seventy-one zoom simulations of a Milky Way-sized (MW) halo, exploring the parameter space for a widely-used star formation and feedback model in the {\tt Enzo} simulation code. We propose a novel way to match observations, using functional fits to the observed baryon makeup over a wide range of halo masses. The model MW galaxy is calibrated using three parameters: the star formation efficiency $\left(f_*\right)$, the efficiency of thermal energy from stellar feedback $\left(\epsilon\right)$ and the region into which feedback is injected $\left(r\ {\rm and}\ s\right)$. We find that changing the amount of feedback energy affects the baryon content most significantly. We then identify two sets of feedback parameter values that are both able to reproduce the baryonic properties for haloes between $10^{10}\,\mathrm{M_\odot}$ and $10^{12}\,\mathrm{M_\odot}$. We can potentially improve the agreement by incorporating more parameters or physics. If we choose to focus on one property at a time, we can obtain a more realistic halo baryon makeup. We show that the employed feedback prescription is insensitive to dark matter mass resolution between $10^5\,{\rm M_\odot}$ and $10^7\,{\rm M_\odot}$. Contrasting both star formation criteria and the corresponding combination of optimal feedback parameters, we also highlight that feedback is self-consistent: to match the same baryonic properties, with a relatively higher gas to stars conversion efficiency, the feedback strength required is lower, and vice versa. Lastly, we demonstrate that chaotic variance in the code can cause deviations of approximately 10\% and 25\% in the stellar and baryon mass in simulations evolved from identical initial conditions.

[27]  arXiv:2002.02683 [pdf, other]

Title: Towards a non-Gaussian model of redshift space distortions

Authors: Carolina Cuesta-Lazaro, Baojiu Li, Alexander Eggemeier, Pauline Zarrouk, Carlton M. Baugh, Takahiro Nishimichi, Masahiro Takada

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

To understand the nature of the accelerated expansion of the Universe, we need to combine constraints on the expansion rate and growth of structure. The growth rate is usually extracted from three dimensional galaxy maps by exploiting the effects of peculiar motions on galaxy clustering. However, theoretical models of the probability distribution function (PDF) of galaxy pairwise peculiar velocities are not accurate enough on small scales to reduce the error on theoretical predictions to the level required to match the precision expected for measurements from future surveys. Here, we improve the modelling of the pairwise velocity distribution by using the Skew-T PDF, which has nonzero skewness and kurtosis. Our model accurately reproduces the redshift-space multipoles (monopole, quadrupole and hexadecapole) predicted by N-body simulations, above scales of about $10\,h^{-1}{\rm Mpc}$. We illustrate how a Taylor expansion of the streaming model can reveal the contributions of the different moments to the clustering multipoles, which are independent of the shape of the velocity PDF. The Taylor expansion explains why the Gaussian streaming model works well in predicting the first two redshift-space multipoles, although the velocity PDF is non-Gaussian even on large scales. Indeed, any PDF with the correct first two moments would produce precise results for the monopole down to scales of about $10\,h^{-1}{\rm Mpc}$, and for the quadrupole down to about $30\,h^{-1}{\rm Mpc}$. An accurate model for the hexadecapole needs to include higher-order moments.

[28]  arXiv:2002.02690 [pdf, other]

Title: VLT/X-shooter spectroscopy of massive young stellar objects in the 30 Doradus region of the Large Magellanic Cloud

Authors: M.L. van Gelder, L. Kaper, J. Japelj, M. C. Ramírez-Tannus, L. E. Ellerbroek, R. H. Barbá, J. M. Bestenlehner, A. Bik, G. Gräfener, A. de Koter, S. E. de Mink, E. Sabbi, H. Sana, M. Sewiło, J. S. Vink, N. R. Walborn

Comments: Accepted to A&A, 26 pages, 19 figures, 4 tables

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

The process of massive star ($M\geq8~M_\odot$) formation is still poorly understood. Observations of massive young stellar objects (MYSOs) are challenging due to their rarity, short formation timescale, large distances, and high circumstellar extinction. Here, we present the results of a spectroscopic analysis of a population of MYSOs in the Large Magellanic Cloud (LMC). We took advantage of the spectral resolution and wavelength coverage of X-shooter (300-2500 nm), mounted on the European Southern Observatory Very Large Telescope, to detect characteristic spectral features in a dozen MYSO candidates near 30 Doradus, the largest starburst region in the Local Group hosting the most massive stars known. The X-shooter spectra are strongly contaminated by nebular emission. We used a scaling method to subtract the nebular contamination from our objects. We detect H$\alpha,\beta$, [O I] 630.0 nm, Ca II infrared triplet, [Fe II] 1643.5 nm, fluorescent Fe II 1687.8 nm, H$_2$ 2121.8 nm, Br$\gamma$, and CO bandhead emission in the spectra of multiple candidates. This leads to the spectroscopic confirmation of 10 candidates as bona fide MYSOs. We compare our observations with photometric observations from the literature and find all MYSOs to have a strong near-infrared excess. We compute lower limits to the brightness and luminosity of the MYSO candidates, confirming the near-infrared excess and the massive nature of the objects. No clear correlation is seen between the Br$\gamma$ luminosity and metallicity. Combining our sample with other LMC samples results in a combined detection rate of disk features such as fluorescent Fe II and CO bandheads which is consistent with the Galactic rate (40\%). Most of our MYSOs show outflow features.

[29]  arXiv:2002.02722 [pdf, other]

Title: Unraveling the nature of a deeply embedded Wolf-Rayet star WR 121a

Authors: Bharti Arora, J. C. Pandey

Comments: 15 Pages, 8 Figures, 2 Tables, Accepted for publication in The Astrophysical Journal

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

An X-ray study of a deeply embedded Wolf-Rayet star WR 121a has been carried out using long-term (spanning over ~12 years) archival observations from Chandra and XMM-Newton. For the first time, a periodic variation with a period of 4.1 days has been detected in the X-ray light curve of WR 121a. No companion is seen in a merged and exposure corrected Chandra X-ray image of WR 121a as shown in the other previous observations in J-band. The X-ray spectrum of WR 121a has been well-explained by a thermal plasma emission model with temperatures of 0.98+/-0.34 keV and 3.55+/-0.69 keV for the cool and hot components, respectively and non-solar abundances. The present study indicates that WR121a is one of the X-ray bright massive binaries with an X-ray luminosity of ~10^34 erg/s, which can be explained by an active wind collision between its components. The phase-locked modulations have been seen in the flux variation of WR 121a where the flux is increased by a factor of ~1.6 from minimum to maximum in 0.3-10.0 keV energy band. These variations could be caused by an eclipse of the wind collision region by the secondary star in a binary orbit. The winds of both components of WR 121a appear to be radiative. Radiative inhibition as well as radiative braking are the most likely processes those are affecting the wind collision severely in this short period massive binary system.

[30]  arXiv:2002.02746 [pdf, other]

Title: Pal 13: its moderately extended low density halo and its accretion history

Authors: Andrés E. Piatti, José G. Fernández-Trincado

Comments: 8 pages, 6 figures. Accepted for publication in Astronomy & Astrophysics

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

We present results on the basis of Dark Energy Camera Legacy Survey (DECaLS) DR8 astrometric and photometric data sets of the Milky Way globular cluster Pal 13. Because of its relative small size and mass, there has not been yet a general consensus about the existence of extra-tidal structures around it. While some previous results claim for the absence of such features, others have shown that the cluster is under the effects of tidal stripping. From DECaLS g,r magnitudes of stars placed along the cluster Main Sequence in the colour-magnitude diagram --previously corrected by interstellar reddening--, we built the cluster stellar density map. The resulting density map shows nearly smooth contours around Pal 13 out to 1.6 times the most recent estimate of its Jacobi radius, derived by taking into account its variation along its orbital motion. This outcome favours the presence of stars escaping the cluster, a phenomenon frequently seen in globular clusters that have crossed the Milky Way disc a comparable large number of times. Particularly, the orbital high eccentricity and large inclination angle of this accreted globular cluster could have been responsible for the relatively large amount of cluster mass lost.

[31]  arXiv:2002.02764 [pdf, ps, other]

Title: Identifying the formation mechanism of redback pulsars

Authors: M. A. De Vito, O. G. Benvenuto, J. E. Horvath

Comments: 7 pages, 3 figures, 2 tables. Accepted for publication in MNRAS

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

We analyse the evolution of close binary systems containing a neutron star that lead to the formation of redback pulsars. Recently there has been some debate on the origin of such systems and the formation mechanism of redbacks may still be considered as an open problem. We show that the operation of a strong evaporation mechanism, starting from the moment when the donor star becomes fully convective (or alternatively since the formation of the neutron star by accretion induced collapse), produces systems with donor masses and orbital periods in the range corresponding to redbacks with donors appreciably smaller than their Roche lobes, i.e., they have low filling factors (lower than $0.75$). Models of redback pulsars can be constructed assuming the occurrence of irradiation feedback. They have been shown to undergo cyclic mass transfer during the epoch at which they attain donor masses and orbital periods corresponding to redbacks, and stay in quasi-Roche lobe overflow conditions with {\it high} filling factors. We show that, if irradiation feedback occurs and radio ejection inhibits further accretion onto the neutron star after the first mass transfer cycle, the redback systems feature {\it high} filling factors. We suggest that the filling factor should be considered as a useful tool for discriminating among those redback formation mechanisms. We compare theoretical results with available observations, and conclude that observations tend to favour models with high filling factors.

[32]  arXiv:2002.02765 [pdf, ps, other]

Title: Field/Isolated lenticular galaxies with high $S_N$ values: the case of NGC 4546 and its globular cluster system

Authors: C. G. Escudero, F. R. Faifer, A. V. Smith Castelli, M. A. Norris, J. C. Forte

Comments: 18 pages, 24 figures. Accepted for publication in MNRAS

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

We present a photometric study of the field lenticular galaxy NGC 4546 using Gemini/GMOS imaging in g'r'i'z'. We perform a 2D image decomposition of the surface brightness distribution of the galaxy using GALFIT, finding that four components adequately describe it. The subtraction of this model from our images and the construction of a colour map allow us to examine in great detail the asymmetric dust structures around the galactic centre. In addition, we perform a detailed analysis of the globular cluster (GC) system of NGC 4546. Using a Gaussian Mixture Model algorithm in the colour-colour plane we detected hints of multiple groups of GC candidates: the classic blue and red subpopulations, a group with intermediate colours that present a concentrated spatial distribution towards the galaxy, and an additional group towards the red end of the colour distribution. We estimate a total GC population for NGC 4546 of $390\pm60$ members and specific frequency $S_N=3.3\pm0.7$, which is relatively high compared to the typical value for galaxies of similar masses and environment. We suggest that the unusual GC population substructures were possibly formed during the interaction that led to the formation of the young ultra-compact dwarf (NGC 4546-UCD1) found in this system. Finally, we estimate the distance modulus of NGC 4546 by analyzing its luminosity function, resulting in $(m-M)=30.75\pm0.12$ mag (14.1 Mpc).

[33]  arXiv:2002.02787 [pdf]

Title: Solar Flare Detection Method using Rn-222 Radioactive Source

Authors: Jonathan Walg, Yaniv Zigel, Anatoly Rodnianski, Itzhak Orion

Comments: arXiv admin note: substantial text overlap with arXiv:1902.10131

Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Nuclear Experiment (nucl-ex); Instrumentation and Detectors (physics.ins-det)

Solar neutrino detection is known to be a very challenging task, due to the minuscule absorption cross-section and mass of the neutrino. One research showed that relative large solar-flares affected the decay-rates of Mn-54 in December 2006. Since most the radiation emitted during a solar flare are blocked before reaching the earth surface, it should be assumed that such decay-rate changes could be due to neutrino flux increase from the sun, in which only neutrinos can penetrate the radionuclide. This study employs the Rn-222 radioactive source for the task of solar flare detection, based on the prediction that it will provide a stable gamma ray counting rate. In order to ascertain counting stability, three counting systems were constructed to track the count-rate changes. The signal processing approach was applied in the raw data analysis. The Rn-222 count-rate measurements showed several radiation counting dips, indicating that the radioactive nuclide can be affected by order of magnitude neutrino flux change from the sun. We conclude that using the cooled Radon source obtained the clearest responses, and therefore this is the preferable system for detecting neutrino emissions from a controlled source.

[34]  arXiv:2002.02795 [pdf, other]

Title: Non-detection of TiO and VO in the atmosphere of WASP-121b using high-resolution spectroscopy

Authors: Stephanie R. Merritt, Neale P. Gibson, Stevanus K. Nugroho, Ernst J. W. de Mooij, Matthew J. Hooton, Shannon M. Matthews, Laura K. McKemmish, Thomas Mikal-Evans, Nikolay Nikolov, David K. Sing, Jessica J. Spake, Chris A. Watson

Comments: 12 pages, 7 figures, accepted for publication in A&A

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

Thermal inversions have long been predicted to exist in the atmospheres of ultra-hot Jupiters. However, detection of two species thought to be responsible -- TiO and VO -- remain elusive. We present a search for TiO and VO in the atmosphere of the ultra-hot Jupiter WASP-121b ($T_\textrm{eq} \gtrsim 2400$ K), an exoplanet already known to show water features in its dayside spectrum characteristic of a temperature inversion as well as tentative evidence for VO at low-resolution. We observed its transmission spectrum with UVES/VLT and used the cross-correlation method -- a powerful tool for the unambiguous identification of the presence of atomic and molecular species -- in an effort to detect whether TiO or VO were responsible for the observed temperature inversion. No evidence for the presence of TiO or VO was found at the terminator of WASP-121b. By injecting signals into our data at varying abundance levels, we set rough detection limits of $[\text{VO}] \lesssim -7.9$ and $[\text{TiO}] \lesssim -9.3$. However, these detection limits are largely degenerate with scattering properties and the position of the cloud deck. Our results may suggest that neither TiO or VO are the main drivers of the thermal inversion in WASP-121b, but until a more accurate line list is developed for VO, we cannot conclusively rule out its presence. Future work will search for finding other strong optically-absorbing species that may be responsible for the excess absorption in the red-optical.

[35]  arXiv:2002.02813 [pdf, ps, other]

Title: On fractal properties of the cosmic web

Authors: J. Einasto, G. Hütsi, T. Kuutma, M. Einasto

Comments: 13 pages,8 figures, submitted to Astronomy & Astrophysics

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

We calculate spatial correlation functions of galaxies, $\xi(r)$, structure functions, $g(r)=1 +\xi(r)$, and fractal dimension functions, $D(x)= 3+\gamma(r) = 3+ d \log g(r)/ d \log r$, using dark matter particles of biased $\Lambda$ cold dark matter (CDM) simulation, observed galaxies of the Sloan Digital Sky Survey (SDSS), and simulated galaxies of the Millennium and EAGLE simulations. We analyse how these functions describe fractal and other geometrical properties of the cosmic web. Correlation functions of biased $\Lambda$CDM model samples describe at small distances (particle/galaxy separations), galaxy samples only brightest galaxies in clusters are visible, and the transition from clusters to filaments occurs at distance $r \approx 0.8 - 1.5$~\Mpc. On larger separations correlation functions describe the distribution of matter and galaxies in the whole cosmic web. The effective fractal dimension of the cosmic web is a continuous function of the distance (separation). On small separations, $ r \le 2$~\Mpc, the fractal dimension decreases from $D \approx 1.5$ to $D \approx 0$, reflecting the distribution inside halos/clusters. The minimum of the fractal dimension function $D(r)$ near $r \approx 2$ is deeper for more luminous galaxies. On medium separations, $2 \le r \le 10$~\Mpc, the fractal dimension grows from $\approx 0$ to $\approx 2$, and approaches at large separations 3 (random distribution). Real and simulated galaxies of low luminosity, $M_r \ge -19$, have almost identical correlation lengths and amplitudes, indicating that dwarf galaxies are satellites of brighter galaxies, and do not form a smooth population in voids.

[36]  arXiv:2002.02816 [pdf, ps, other]

Title: The Aarhus red giants challenge II. Stellar oscillations in the red giant branch phase

Authors: J. Christensen-Dalsgaard, V. Silva Aguirre, S. Cassisi, A. Serenelli, A. Weiss, G. Angelou, Y. Lebreton, M. Miller Bertolami, D. Stello, E. Bellinger, T. Constantino, P. Eggenberger, C. Jiang, R. M. Ouazzani, A. Pietrinferni, R. H. D. Townsend, D. Bossini, S. Deheuvels, A. Jendreieck, A. Mazumdar, A. Miglio, M. Salaris

Comments: Astronomy and Astrophysics, in the press

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

Context. The large quantity of high-quality asteroseismic data that obtained from space-based photometric missions and the accuracy of the resulting frequencies motivate a careful consideration of the accuracy of computed oscillation frequencies of stellar models, when applied as diagnostics of the model properties.
Aims. Based on models of red-giant stars that have been independently calculated using different stellar evolution codes, we investigate the extent to which the differences in the model calculation affect the model oscillation frequencies.
Methods. For each of the models, which cover four different masses and different evolution stages on the red-giant branch, we computed full sets of low-degree oscillation frequencies using a single pulsation code and, from these frequencies, typical asteroseismic diagnostics. In addition, we carried out preliminary analyses to relate differences in the oscillation properties to the corresponding model differences.
Results. In general, the differences in asteroseismic properties between the different models greatly exceed the observational precision of these properties, in particular for the nonradial modes whose mixed acoustic and gravity-wave character makes them sensitive to the structure of the deep stellar interior. In some cases, identifying these differences led to improvements in the final models presented here and in Paper I; here we illustrate particular examples of this.
Conclusions. Further improvements in stellar modelling are required in order fully to utilise the observational accuracy to probe intrinsic limitations in the modelling. However, our analysis of the frequency differences and their relation to stellar internal properties provides a striking illustration of the potential of the mixed modes of red-giant stars for the diagnostics of stellar interiors.

[37]  arXiv:2002.02822 [pdf, other]

Title: The impact of AGN feedback on the 1D power spectra from the Ly$α$ forest using the Horizon-AGN suite of simulations

Authors: Chabanier Solène, Bournaud Frédéric, Dubois Yohan, Palanque-Delabrouille Nathalie, Yèche Christophe, Armengaud Eric, Peirani Sébastien

Comments: Submitted to MNRAS

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

The Lyman-$\alpha$ forest is a powerful probe for cosmology, but it is also strongly impacted by galaxy evolution and baryonic processes such as Active Galactic Nuclei (AGN) feedback, which can redistribute mass and energy on large scales. We constrain the signatures of AGN feedback on the 1D power spectrum of the Lyman-$\alpha$ forest using a series of eight hydro-cosmological simulations performed with the Adaptative Mesh Refinement code RAMSES. This series starts from the Horizon-AGN simulation and varies the sub-grid parameters for AGN feeding, feedback and stochasticity. These simulations cover the whole plausible range of feedback and feeding parameters according to the resulting galaxy properties. AGNs globally suppress the Lyman-$\alpha$ power at all scales. On large scales, the energy injection and ionization dominate over the supply of gas mass from AGN-driven galactic winds, thus suppressing power. On small scales, faster cooling of denser gas mitigates the suppression. This effect increases with decreasing redshift. We provide lower and upper limits of this signature at nine redshifts between $z=4.25$ and $z=2.0$, making it possible to account for it at post-processing stage in future work given that running simulations without AGN feedback can save considerable amounts of computing resources. Ignoring AGN feedback in cosmological inference analyses leads to strong biases with 2\% shift on $\sigma_8$ and 1\% shift on $n_s$, which represents twice the standards deviation of the current constraints on $n_s$.

[38]  arXiv:2002.02828 [pdf, other]

Title: On the shape of the local bubble

Authors: Lorenzo Zaninetti

Comments: 13 pages, 11 figures

Journal-ref: published on The International Journal of Astronomy and Astrophysics 2020, 10,11-27

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

The shape of the local bubble is modeled in the framework of the thin layer approximation. The asymmetric shape of the local bubble is simulated by introducing axial profiles for the density of the interstellar medium, such as exponential, Gaussian, inverse square dependence and Navarro--Frenk--White. The availability of some observed asymmetric profiles for the local bubble allows us to match theory and observations via the observational percentage of reliability. The model is compatible with the presence of radioisotopes on Earth.

[39]  arXiv:2002.02833 [pdf, other]

Title: Accelerating linear system solvers for time domain component separation of cosmic microwave background data

Authors: J. Papez, L. Grigori, R. Stompor

Subjects: Numerical Analysis (math.NA); Cosmology and Nongalactic Astrophysics (astro-ph.CO); Computational Physics (physics.comp-ph)

Component separation is one of the key stages of any modern, cosmic microwave background (CMB) data analysis pipeline. It is an inherently non-linear procedure and typically involves a series of sequential solutions of linear systems with similar, albeit not identical system matrices, derived for different data models of the same data set. Sequences of this kind arise for instance in the maximization of the data likelihood with respect to foreground parameters or sampling of their posterior distribution. However, they are also common in many other contexts. In this work we consider solving the component separation problem directly in the measurement (time) domain, which can have a number of important advantageous over the more standard pixel-based methods, in particular if non-negligible time-domain noise correlations are present as it is commonly the case. The time-domain based approach implies, however, significant computational effort due to the need to manipulate the full volume of time-domain data set. To address this challenge, we propose and study efficient solvers adapted to solving time-domain-based, component separation systems and their sequences and which are capable of capitalizing on information derived from the previous solutions. This is achieved either via adapting the initial guess of the subsequent system or through a so-called subspace recycling, which allows to construct progressively more efficient, two-level preconditioners. We report an overall speed-up over solving the systems independently of a factor of nearly 7, or 5, in the worked examples inspired respectively by the likelihood maximization and likelihood sampling procedures we consider in this work.

[40]  arXiv:2002.02840 [pdf, other]

Title: Occurrence and Architecture of Kepler Planetary Systems as Functions of Stellar Mass and Effective Temperature

Authors: Jia-Yi Yang (Nanjing), Ji-Wei Xie (Nanjing), Ji-Lin Zhou (Nanjing)

Comments: 25 pages, 21 figures, 2 tables, accepted for publication in AJ

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

The Kepler mission has discovered thousands of exoplanets around various stars with different spectral types (M, K, G and F) and thus different masses and effective temperatures. Previous studies have shown that planet occurrence rate, in terms of average number of planets per star, drops with increasing stellar effective temperature (Teff). In this paper, with the final Kepler Data Release (DR25) catalog, we revisit the relation between stellar effective temperature (as well as mass) and planet occurrence, but in terms of the fraction of stars with planets and the number of planets per planetary system (i.e. planet multiplicity). We find that both the fraction of stars with planets and planet multiplicity decrease with increasing stellar temperature and mass. Specifically, about 75% late type stars (Teff<5000 K) have Kepler-like planets with an average planet multiplicity of ~2.8; while for early type stars (Teff>6500 K), this fraction and the average multiplicity fall down to ~35% and ~1.8, respectively. The decreasing trend in fraction of stars with planets is very significant with $\Delta$AIC> 30, though the trend in planet multiplicity is somewhat tentative with $\Delta$AIC~5. Our results also allow us to derive the dispersion of planetary orbital inclinations in relationship with stellar effective temperature. Interestingly, it is found to be similar to the well-known trend between obliquity and stellar temperature, indicating that the two trends might have a common origin.

[41]  arXiv:2002.02847 [pdf, ps, other]

Title: Signatures of the Galactic bar in high-order moments of proper motions measured by Gaia

Authors: Pedro Alonso Palicio, Inma Martinez-Valpuesta, Carlos Allende Prieto, Claudio Dalla Vecchia

Comments: 11 pages, 9 figures, accepted in A&A

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

Our location in the Milky Way provides an exceptional opportunity to gain insight on the galactic evolution processes, and complement the information inferred from observations of external galaxies. Since the Milky Way is a barred galaxy, the study of motions of individual stars in the bulge and disc is useful to understand the role of the bar. The Gaia mission enables such study by providing the most precise parallaxes and proper motions to date. In this theoretical work, we explore the effects of the bar on the distribution of higher-order moments --the skewness and kurtosis-- of the proper motions by confronting two simulated galaxies, one with a bar and one nearly axisymmetric, with observations from the latest Gaia data release (GaiaDR2). We introduce the code ASGAIA to account for observational errors of Gaia in the kinematical structures predicted by the numerical models. As a result, we find clear imprints of the bar in the skewness distribution of the longitudinal proper motion $\mu_\ell$ in GaiaDR2, as well as other features predicted for the next Gaia data releases.

[42]  arXiv:2002.02858 [pdf, other]

Title: The VIRUS-P Exploration of Nearby Galaxies (VENGA): The stellar populations and assembly of NGC 2903's bulge, bar, and outer disc

Authors: Andreia Carrillo, Shardha Jogee, Niv Drory, Kyle F. Kaplan, Guillermo Blanc, Tim Weinzirl, Mimi Song, Rongxin Luo

Comments: 14 pages, 9 figures, 2 tables, accepted in MNRAS

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

We study the stellar populations and assembly of the nearby spiral galaxy NGC 2903's bulge, bar, and outer disc using the VIRUS-P Exploration of Nearby Galaxies IFS survey. We observe NGC 2903 with a spatial resolution of 185 pc using the Mitchell Spectrograph's 4.25 arcsec fibres at the 2.7 Harlan J. Smith telescope. Bulge-bar-disc decomposition on the 2MASS Ks-band image of NGC 2903 shows that it has ~6%, 6%, and 88%, of its stellar mass in the bulge, bar, and outer disc, respectively, and its bulge has a low Sersic index of ~0.27, suggestive of a disky bulge. We perform stellar population synthesis and find that the outer disc has 46% of its mass in stars >5 Gyr, 48% in stars between 1 and 5 Gyr, and <10% in younger stars. Its stellar bar has 65% of its mass in ages 1-5 Gyr and has metallicities similar to the outer disc, suggestive of the evolutionary picture where the bar forms from disc material. Its bulge is mainly composed of old high-metallicity stars though it also has a small fraction of young stars. We find enhanced metallicity in the spiral arms and central region, tracing areas of high star formation as seen in the Halpha map. These results are consistent with the idea that galaxies of low bulge-to-total mass ratio and low bulge Sersic index like NGC 2903 has not had a recent major merger event, but has instead grown mostly through minor mergers and secular processes.

[43]  arXiv:2002.02861 [pdf]

Title: Microlensing Analysis for the gravitational lens systems SDSS0924+0219, Q1355-2257, and SDSS1029+2623

Authors: K. Rojas, V. Motta, E. Mediavilla, J. JimÉnez-Vicente, E. Falco, C. Fian

Comments: 9 pages, 12 figures

Journal-ref: The Astrophysical Journal, 890:3 (9pp), 2020 February 10

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

We use spectroscopic observations of the gravitationally lensed systems SDSS0924+0219(BC), Q1355-2257(AB), and SDSS1029+2623(BC) to analyze microlensing and dust extinction in the observed components. We detect chromatic microlensing effects in the continuum and microlensing in the broad emission line profiles of the systems SDSS0924+0219(BC), and Q1355-2257(AB). Using magnification maps to simulate microlensing and modeling the emitting region as a Gaussian intensity profile with size $r_s \propto \lambda ^p$, we obtain the probability density functions for a logarithmic size prior at $\lambda_{rest-frame}=3533$ {\AA}. In the case of SDSS0924+0219, we obtain: $r_s = 4^{+3}_{-2}$ $\sqrt{M/M_{\odot}}$ light-days (at $1 \sigma$), which is larger than the range of other estimates, and $p = 0.8 \pm 0.2$ (at $1 \sigma$), which is smaller than predicted by the thin disk theory, but still in agreement with previous results. In the case of Q1355-2257 we obtain (at $1 \sigma$): $r_s = 3.6^{+3.0}_{-1.6}$ $\sqrt{M/M_{\odot}}$ light-days, which is also larger than the theoretical prediction, and $p = 2.0 \pm 0.7$ that is in agreement with the theory within errors. SDSS1029+2326 spectra show evidence of extinction, probably produced by a galaxy in the vicinity of image C. Fitting an extinction curve to the data we estimate $\Delta E \sim 0.2$ in agreement with previous results. We found no evidence of microlensing for this system.

[44]  arXiv:2002.02888 [pdf, other]

Title: Detecting the anisotropic astrophysical gravitational wave background in the presence of shot noise through cross-correlations

Authors: David Alonso, Giulia Cusin, Pedro G. Ferreira, Cyril Pitrou

Comments: 8 pages, 1 figure

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

The spatial and temporal discreteness of gravitational wave sources leads to shot noise that may, in some regimes, swamp any attempts at measuring the anisotropy of the gravitational wave background. Cross-correlating a gravitational wave background map with a sufficiently dense galaxy survey can alleviate this issue, and potentially recover some of the underlying properties of the gravitational wave background. We quantify the shot noise level and we explicitly show that cross-correlating the gravitational wave background and a galaxy catalog improves the chances of a first detection of the background anisotropy with a gravitational wave observatory operating in the frequency range (10Hz,100Hz), given sufficient sensitivity.

[45]  arXiv:2002.02894 [pdf, other]

Title: A Massive Young Runaway Star in W49 North

Authors: Luis F. Rodriguez, Roberto Galvan-Madrid, Joel Sanchez-Bermudez, Christopher G. De Pree

Comments: 11 pages, 6 figures,to appear in ApJ

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

We analyzed high angular resolution 45.5 GHz images of the W49 North massive star forming region obtained in 1998 and 2016 with the Very Large Array. Most of the ultracompact HII regions show no detectable changes over the time interval of the observations. However, subcomponents B1, B2, G2a and G2c have increased its peak flux densities by values in the range of 3.8 to 21.4 \%. Most interestingly, the cometary region C clearly shows proper motions that at the distance of the region are equivalent to a velocity of 76$\pm$6 km s$^{-1}$ in the plane of the sky. We interpret this region as the ionized bowshock produced by a runaway O6 ZAMS star that was ejected from the eastern edge of Welch's ring about 6,400 years ago.

[46]  arXiv:2002.02906 [pdf, other]

Title: MUSE observations of NGC330 in the Small Magellanic Cloud. Helium abundance of bright main sequence stars

Authors: R. Carini, K. Biazzo, E. Brocato, L. Pulone, L. Pasquini

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

We present observations of the most bright main sequence stars in the Small Magellanic Cloud stellar cluster NGC330 obtained with the integral field spectrograph MUSE@VLT. The use of this valuable instrument allows us to study both photometric and spectroscopic properties of stellar populations of this young star cluster.
The photometric data provide us a precise color magnitude diagram, which seems to support the presence of two stellar populations of ages of $\sim$ 18 Myr and $\sim$ 30 Myr assuming a metallicity of Z = 0.002. Thanks to the spectroscopic data, we derive helium abundance of 10 main sequence stars within the effective radius Reff= 20" of NGC330, thus leading to an estimation of $\epsilon(He)$ = 10.93 $\pm$ 0.05 (1$\sigma$ ). The helium elemental abundances of stars likely belonging to the two possible stellar populations, do not show differences or dichotomy within the uncertainties. Thus, our results suggest that the two stellar populations of NGC330, if they exist, share similar original He abundances.
If we consider stellar rotation velocity in our analysis, a coeval (30 Myr) stellar population, experiencing different values of rotation, cannot be excluded. In this case, the mean helium abundance < $\epsilon(He)$ >rot obtained in our analysis is 11.00 $\pm$ 0.05 dex. We also verified that possible NLTE effects cannot be identified with our analysis because of the spectral resolution and they are within our derived abundance He uncertainties.
Moreover, the analysis of the He abundance as a function of the distance from the cluster center of the observed stars do not show any correlation.

[47]  arXiv:2002.02945 [pdf, other]

Title: Unveiling cloudy exoplanets: the influence of cloud model choices on retrieval solutions

Authors: Joanna K. Barstow

Comments: 12 pages, 8 figures. Submitted to MNRAS

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

In recent years, it has become clear that a substantial fraction of transiting exoplanets have some form of aerosol present in their atmospheres. Transit spectroscopy - mostly of hot Jupiters, but also of some smaller planets - has provided evidence for this, in the form of steep downward slopes from blue to red in the optical part of the spectrum, and muted gas absorption features throughout. Retrieval studies seeking to constrain the composition of exoplanet atmospheres must therefore account for the presence of aerosols. However, clouds and hazes are complex physical phenomena, and the transit spectra that are currently available allow us to constrain only some of their properties. Therefore, representation of aerosols in retrieval models requires that they are described by only a few parameters, and this has been done in a variety of ways within the literature. Here, I investigate a range of parameterisations for exoplanet aerosol and their effects on retrievals from transmission spectra of hot Jupiters HD 189733b and HD 209458b. I find that results qualitatively agree for the cloud/haze itself regardless of the parameterisation used, and indeed using multiple approaches provides a more holistic picture; the retrieved abundance of H2O is also very robust to assumptions about aerosols. I also find strong evidence that aerosol on HD 209458b covers less than half of the terminator region, whilst the picture is less clear for HD 189733b.

[48]  arXiv:2002.02951 [pdf, other]

Title: Broadband X-ray analysis of 1E 1740.7-2942: constraints on spin, inclination and a tentative black hole mass

Authors: Paulo E. Stecchini, Flavio D'Amico, Francisco Jablonski, Manuel Castro, Joao Braga

Comments: 12 pages, 10 figures. accepted by MNRAS for publication

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

1E 1740.7-2942 is one of the strongest hard X-ray emitters in the Galactic Centre region, believed to be a black hole in a high-mass X-ray binary system. Although extensively studied in X-rays, many aspects about the underlying nature of the system are still unknown. For example, X-ray data analyses of 1E 1740.7-2942 up to date have not yet unveiled the signature of a reflection component, whose modelling could be used to estimate parameters such as the spin of the black hole and inclination of the disc. We report here on the determination of these parameters from the analysis of the reflection component present in a public \textit{NuSTAR} observation which hasn't been subject to any previous study. We include \textit{XMM-Newton} and \textit{INTEGRAL} data to build a combined spectrum, enabling a joint analysis of both the disc and comptonisation components. Results point to a relatively high inclination disc $\gtrsim$ 50$^{\circ}$ (3 $\sigma$) and a near-maximum speed rotating black hole. The former is in agreement with a previous radio study and the latter is reported here for the first time. Lastly, we follow the methodology of recent efforts to weight black holes with only X-ray spectra and find results that suggest a black hole mass of about 5 M$_\odot$ for 1E 1740.7-2942.

[49]  arXiv:2002.02952 [pdf, other]

Title: Resonant backreaction in axion inflation

Authors: Valerie Domcke, Veronica Guidetti, Yvette Welling, Alexander Westphal

Comments: LaTeX, 1+28 pages, 10 figures

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

Axion inflation entails a coupling of the inflaton field to gauge fields through the Chern-Simons term. This results in a strong gauge field production during inflation, which backreacts on the inflaton equation of motion. Here we show that this strongly non-linear system generically experiences a resonant enhancement of the gauge field production, resulting in oscillatory features in the inflaton velocity as well as in the gauge field spectrum. The gauge fields source a strongly enhanced scalar power spectrum at small scales, exceeding previous estimates. For appropriate parameter choices, the collapse of these over-dense regions can lead to a large population of (light) primordial black holes with remarkable phenomenological consequences.

[50]  arXiv:2002.02961 [pdf, other]

Title: From the Inner to Outer Milky Way: A Pristine Sample of 4.3 Million Red Clump Stars

Authors: Madeline Lucey, Yuan-Sen Ting, Nesar S. Ramachandra, Keith Hawkins

Comments: 18 pages, 13 figures, 2 tables, submitted to MNRAS

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

Large pristine samples of red clump stars are highly sought after given that they are standard candles and give precise distances even at large distances. However, it is difficult to cleanly select red clumps stars because they can have the same $\rm{T_{eff}}$ and log $g$ as red giant branch stars. Recently, it was shown that the asteroseismic parameters, $\rm{\Delta P}$ and $\rm{\Delta \nu}$, which are used to accurately select red clump stars, can be derived from spectra using the change in the surface carbon to nitrogen ratio ([C/N]) caused by mixing during the red giant branch. This change in [C/N] can also impact the spectral energy distribution. In this study, we predict the $\rm{\Delta P}$, $\rm{\Delta \nu}$, $\rm{T_{eff}}$ and log $g$ using 2MASS, AllWISE, $Gaia$, and Pan-STARRS data in order to select a clean sample of red clump stars. Training on a sample with known parameters, we achieve a contamination rate of $\sim$20%, equivalent to what is achieved when selecting from $\rm{T_{eff}}$ and log $g$ derived from low resolution spectra. Finally, we present two red clump samples. One sample has a contamination rate of $\sim$20% and $\sim$510,000 red clump stars. The other has a contamination of $\sim$35% and $\sim$4.3 million red clump stars which includes over 280,000 stars at distances $>$ 10 kpc. The scientific potential of this catalog for studying the structure and formation history of the Galaxy is vast given that it includes millions of precise distances to stars in the inner bulge and distant halo where astrometric distances are imprecise.

Cross-lists for Mon, 10 Feb 20

[51]  arXiv:2002.01931 (cross-list from hep-ph) [pdf, other]

Title: Superheavy dark matter in $R+R^2$ cosmology with conformal anomaly

Authors: E. V. Arbuzova, A. D. Dolgov, R. S. Singh

Comments: 14 pages, 11 figures

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

Cosmological evolution and particle creation in $R^2$-modified gravity is considered for the case of the dominant decay of the scalaron into a pair of gauge bosons due to conformal anomaly. It is shown that in the process of thermalization superheavy dark matter with the coupling strength typical for the GUT SUSY can be created. Such dark matter would have the proper cosmological density if the particle mass is close to $10^{12}$ GeV.

[52]  arXiv:2002.02460 (cross-list from cs.LG) [pdf, other]

Title: Intelligent Arxiv: Sort daily papers by learning users topics preference

Authors: Ezequiel Alvarez (ICAS), Federico Lamagna (CAB), Cesar Miquel (Easytech), Manuel Szewc (ICAS)

Comments: We are open to new ideas and to scientists and institutions wishing to collaborate and/or partner in further improvements for this service. With this tool the time a paper is sent is irrelevant for its order of appearance

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

Current daily paper releases are becoming increasingly large and areas of research are growing in diversity. This makes it harder for scientists to keep up to date with current state of the art and identify relevant work within their lines of interest. The goal of this article is to address this problem using Machine Learning techniques. We model a scientific paper to be built as a combination of different scientific knowledge from diverse topics into a new problem. In light of this, we implement the unsupervised Machine Learning technique of Latent Dirichlet Allocation (LDA) on the corpus of papers in a given field to: i) define and extract underlying topics in the corpus; ii) get the topics weight vector for each paper in the corpus; and iii) get the topics weight vector for new papers. By registering papers preferred by a user, we build a user vector of weights using the information of the vectors of the selected papers. Hence, by performing an inner product between the user vector and each paper in the daily Arxiv release, we can sort the papers according to the user preference on the underlying topics.
We have created the website IArxiv.org where users can read sorted daily Arxiv releases (and more) while the algorithm learns each users preference, yielding a more accurate sorting every day. Current IArxiv.org version runs on Arxiv categories astro-ph, gr-qc, hep-ph and hep-th and we plan to extend to others. We propose several new useful and relevant implementations to be additionally developed as well as new Machine Learning techniques beyond LDA to further improve the accuracy of this new tool.

[53]  arXiv:2002.02534 (cross-list from physics.comp-ph) [pdf, other]

Title: Fast inference of Boosted Decision Trees in FPGAs for particle physics

Authors: Sioni Summers, Giuseppe Di Guglielmo, Javier Duarte, Philip Harris, Duc Hoang, Sergo Jindariani, Edward Kreinar, Vladimir Loncar, Jennifer Ngadiuba, Maurizio Pierini, Dylan Rankin, Nhan Tran, Zhenbin Wu

Subjects: Computational Physics (physics.comp-ph); Instrumentation and Methods for Astrophysics (astro-ph.IM); Machine Learning (cs.LG); High Energy Physics - Experiment (hep-ex)

We describe the implementation of Boosted Decision Trees in the hls4ml library, which allows the conversion of a trained model into an FPGA firmware through an automatic highlevel-synthesis conversion. Thanks to its full on-chip implementation, hls4ml allows performance of inference of Boosted Decision Tree models with extremely low latency. A benchmark model achieving near state of the art classification performance is implemented on an FPGA with 60 ns inference latency, using 8% of the Look Up Tables of the target device. This solution is compatible with the needs of fast real-time processing such as the L1 trigger system of a typical collider experiment.

[54]  arXiv:2002.02555 (cross-list from gr-qc) [pdf, other]

Title: Axisymmetric deformations of neutron stars and gravitational-wave astronomy

Authors: Guilherme Raposo, Paolo Pani

Comments: 12 pages, 4 figures. Relevant codes to construct deformed NS solutions are publicly available at this https URL

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

Einstein's theory of general relativity predicts that the only stationary configuration of an isolated black hole is the Kerr spacetime, which has a unique multipolar structure and a spherical shape when non-spinning. This is in striking contrast to the case of other self-gravitating objects, which instead can in principle have arbitrary deformations even in the static case. Here we develop a general perturbative framework to construct stationary stars with small axisymmetric deformations, and study explicitly compact stars with an intrinsic quadrupole moment. The latter can be sustained, for instance, by crust stresses or strong magnetic fields. While our framework is general, we focus on quadrupolar deformations of neutron stars induced by an anisotropic crust, which continuously connect to spherical neutron stars in the isotropic limit. Deformed neutron stars might provide a more accurate description for stellar remnants formed in supernovae and in binary mergers, and can be used to improve constraints on the neutron-star equation of state through gravitational-wave detections and through the observation of low-mass X-ray binaries. We argue that, if the (dimensionless) intrinsic quadrupole moment is of a few percent or higher, the effect of the deformation is stronger than that of tidal interactions in coalescing neutron-star binaries, and might also significantly affect the electromagnetic signal from accreting neutron stars.

[55]  arXiv:2002.02621 (cross-list from hep-ph) [pdf, other]

Title: Neutrino quantum decoherence engendered by neutrino radiative decay

Authors: Konstantin Stankevich, Alexander Studenikin

Comments: 8 pages in LaTex, accepted for publication in Physical Review D

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

A new theoretical framework, based on the quantum field theory of open systems applied to neutrinos, has been developed to describe the neutrino evolution in external environments accounting for the effect of the neutrino quantum decoherence. The developed new approach enables one to obtain the explicit expressions of the decoherence and relaxation parameters that account for a particular process, in which the neutrino participates, and also for the characteristics of an external environment and of the neutrino itself, including the neutrino energy. We have used this approach to consider a new mechanism of the neutrino quantum decoherence engendered by the neutrino radiative decay to photons and dark photons in an astrophysical environment. The importance of the performed studies is highlighted by the prospects of the forthcoming new large volume neutrino detectors that will provide new frontier in high-statistics measurements of neutrino fluxes from supernovae.

[56]  arXiv:2002.02695 (cross-list from gr-qc) [pdf, other]

Title: New accelerating solutions in late-time cosmology

Authors: Michele Cicoli, Giuseppe Dibitetto, Francisco G. Pedro

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

Dark energy models can be seen as dynamical systems. In this paper we show that multi-field models with a curved field space give rise to new critical points and we analyse their stability. These are new accelerating solutions in late-time cosmology which exist even for steep potentials. This opens up the possibility to realise quintessence models even when quantum corrections spoil the flatness of the underlying potential. These non-linear sigma models arise naturally in supergravity and string models where their multi-field dynamics can help to avoid swampland bounds.

[57]  arXiv:2002.02791 (cross-list from physics.ins-det) [pdf]

Title: Intersatellite-link demonstration mission between CubeSOTA (LEO CubeSat) and ETS9-HICALI (GEO satellite)

Authors: Alberto Carrasco-Casado, Phong Xuan Do, Dimitar Kolev, Takayuki Hosonuma, Koichi Shiratama, Hiroo Kunimori, Phuc V. Trinh, Yuma Abe, Shinichi Nakasuka, Morio Toyoshima

Comments: 5 pages, 10 figures, 3 tables

Journal-ref: Proceedings of the 2019 IEEE International Conference on Space Optical Systems and Applications (ICSOS)

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

LEO-to-GEO intersatellite links using laser communications bring important benefits to greatly enhance applications such as downloading big amounts of data from LEO satellites by using the GEO satellite as a relay. By using this strategy, the total availability of the LEO satellite increases from less than 1% if the data is downloaded directly to the ground up to about 60% if the data is relayed through GEO. The main drawback of using a GEO relay is that link budget is much more difficult to close due to the much larger distance. However, this can be partially compensated by transmitting at a lower data rate, and still benefiting from the much-higher link availability when compared to LEO-to-ground downlinks, which additionally are more limited by the clouds than the relay option. After carrying out a feasibility study, NICT and the University of Tokyo started preparing a mission to demonstrate the technologies needed to perform these challenging lasercom links. Furthermore, to demonstrate the feasibility of this technique, an extremely-small satellite, i.e. a 6U CubeSat, will be used to achieve data rates as high as 10 Gbit/s between LEO and GEO. Some of the biggest challenges of this mission are the extremely low size, weight and power available in the CubeSat, the accurate pointing precision required for the lasercom link, and the difficulties of closing the link at such a high speed as 10 Gbit/s.

[58]  arXiv:2002.02935 (cross-list from hep-ph) [pdf, other]

Title: Constraints on long range force from perihelion precession of planets in a gauged $L_e-L_{μ,τ}$ scenario

Authors: Tanmay Kumar Poddar, Subhendra Mohanty, Soumya Jana

Comments: 16 pages, 2 figures, 2 tables

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

The standard model particles can be gauged in an anomaly free way by three possible gauge symmetries namely ${L_e-L_\mu}$, ${L_e-L_\tau}$, and ${L_\mu-L_\tau}$. Of these, ${L_e-L_\mu}$ and ${L_e-L_\tau}$ forces can mediate between the Sun and the planets and change planetary orbits. It is well known that a deviation from the $1/r^2$ Newtonian force can give rise to a perihelion advancement in the planetary orbit, for instance, as in the well known case of Einstein's gravity which was tested from the observation of the perihelion advancement of the Mercury. We consider the Yukawa potential of ${L_e-L_{\mu,\tau}}$ force which arises between the Sun and the planets if the mass of the gauge boson is $M_{Z^{\prime}}\leq \mathcal{O}(10^{-19})\rm {eV}$. We derive the formula for the perihelion advancement for such Yukawa type fifth force. We find that perihelion advancement is proportional to the square of the semi major axis of the orbit for the Yukawa potential, unlike GR, where it is largest for the nearest planet. We take the observational limits of all planets for which the perihelion advancement is measured and we obtain the gauge boson coupling $g$ in the range $10^{-18}$ to $10^{-16}$ for the mass range $10^{-22}$eV to $10^{-18}$eV. This mass range of gauge boson can be a possible candidate of fuzzy dark matter whose effect can therefore be observed in the precession measurement of the planetary orbits.

[59]  arXiv:2002.02941 (cross-list from hep-th) [pdf, ps, other]

Title: Swampland, Trans-Planckian Censorship and Fine-Tuning Problem for Inflation: Tunnelling Wavefunction to the Rescue

Authors: Suddhasattwa Brahma, Robert Brandenberger, Dong-han Yeom

Comments: 14 pages, comments welcome

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

The trans-Planckian censorship conjecture implies that single-field models of inflation require an extreme fine-tuning of the initial conditions due to the very low-scale of inflation. In this work, we show how a quantum cosmological proposal -- namely the tunneling wavefunction -- naturally provides the necessary initial conditions without requiring such fine-tunings. More generally, we show how the tunneling wavefunction can provide suitable initial conditions for hilltop inflation models, the latter being typically preferred by the swampland constraints.

Replacements for Mon, 10 Feb 20

[60]  arXiv:1401.6892 (replaced) [pdf, other]

Title: Breaking the spell of Gaussianity: forecasting with higher order Fisher matrices

Authors: Elena Sellentin (ITP, U. Heidelberg), Miguel Quartin (Rio de Janeiro Federal U.), Luca Amendola (ITP, U. Heidelberg)

Comments: v3: Corrected an error in Appendix A. Results and conclusions unchanged. v2: New figures and references added. Typos corrected. Matches published version. 10 pages, 6 figures

Journal-ref: MNRAS (2014) 441 (2): 1831-1840

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

[61]  arXiv:1708.05513 (replaced) [pdf, other]

Title: Yarkovsky Drift Detections for 247 Near-Earth Asteroids

Authors: Adam H. Greenberg, Jean-Luc Margot, Ashok K. Verma, Patrick A. Taylor, Susan E. Hodge

Comments: 27 pages, 9 figures, published in the Astronomical Journal, 159, 92, 2020

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

[62]  arXiv:1807.09397 (replaced) [pdf, other]

Title: Singularities of plane gravitational waves and their memory effects

Authors: Tongzheng Wang, Jared Fier, Bowen Li, Guoliang Lv, Zhaojun Wang, Yumei Wu, Anzhong Wang

Comments: revtex4-1, one figure. Corrected some typos. Version to be published in Gen. Relativ. Grav

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

[63]  arXiv:1810.09934 (replaced) [pdf, other]

Title: Inflationary Cosmology: From Theory to Observations

Authors: J. Alberto Vázquez, Luis E. Padilla, Tonatiuh Matos

Comments: Lecture Notes in Cosmology. 37 pages, 15 figures, 2 tables

Journal-ref: Revista Mexicana de F\'isica E, 2020

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

[64]  arXiv:1902.03294 (replaced) [pdf, other]

Title: The Transverse-Traceless Spin-2 Gravitational Wave Cannot Be A Standalone Observable Because It Is Acausal

Authors: Yi-Zen Chu, Yen-Wei Liu

Comments: v3: 64 pages, 1 figure, 4D Minkowski results summarized in Sec. VI, version accepted by CQG. v4: Minor corrections made

Journal-ref: Class. Quantum Grav. 37 (2020) 055001

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

[65]  arXiv:1906.03575 (replaced) [pdf, other]

Title: A Probabilistic Approach to Kepler Completeness and Reliability for Exoplanet Occurrence Rates

Authors: Steve Bryson, Jeffrey Coughlin, Natalie M. Batalha, Travis Berger, Dan Huber, Christopher Burke, Jessie Dotson, Susan E. Mullally

Comments: Accepted for publication in The Astronomical Journal

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

[66]  arXiv:1906.09475 (replaced) [pdf, other]

Title: Neutrino spin-flavor oscillations in solar environment

Authors: Sandeep Joshi, Sudhir R. Jain

Comments: 17 pages, 6 figures

Subjects: High Energy Physics - Phenomenology (hep-ph); Solar and Stellar Astrophysics (astro-ph.SR)

[67]  arXiv:1907.01838 (replaced) [pdf, other]

Title: A preliminary forecast for cosmological parameter estimation with gravitational-wave standard sirens from TianQin

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

Comments: 10 pages, 6 figures

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

[68]  arXiv:1907.07151 (replaced) [pdf]

Title: Atmospheric Electricity at the Ice Giants

Authors: K. L. Aplin, G. Fischer, T. A. Nordheim, A. Konovalenko, V. Zakharenko, P. Zarka

Comments: Revised version for Space Science Reviews

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

[69]  arXiv:1908.07033 (replaced) [pdf, other]

Title: Pattern of perturbations from a coherent quantum inflationary horizon

Authors: Craig Hogan

Comments: Revised version for publication in Classical and Quantum Gravity

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

[70]  arXiv:1908.10813 (replaced) [pdf, ps, other]

Title: Quasinormal Modes of Generalized Black Holes: delta-Kerr Spacetime

Authors: Alireza Allahyari, Hassan Firouzjahi, Bahram Mashhoon

Comments: 21 pages, 1 figure; v2: expanded version; v3: minor improvements, references added; v4: expanded version to appear in CQG; v5: minor corrections

Journal-ref: Classical Quantum Gravity 37, 055006 (2020)

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

[71]  arXiv:1910.04741 (replaced) [pdf, ps, other]

Title: Trans-Planckian censorship, inflation and excited initial states for perturbations

Authors: Suddhasattwa Brahma

Comments: 15 pages, comments welcome; typos corrected, refs added & minor revisions; v3: matches published version

Journal-ref: Phys. Rev. D 101, 023526 (2020)

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

[72]  arXiv:1910.07981 (replaced) [pdf, other]

Title: Mass bound for primordial black hole from trans-Planckian censorship conjecture

Authors: Rong-Gen Cai, Shao-Jiang Wang

Comments: v1, 6 pages, 2 figures; v2, references added; v3, presentation improved, accepted by PRD; v4, to match the published version

Journal-ref: Phys. Rev. D101 (2020) 043508

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

[73]  arXiv:1910.08667 (replaced) [pdf, other]

Title: Are long-term $N$-body simulations reliable?

Authors: David M. Hernandez (1 and 2), Sam Hadden (1), Junichiro Makino (2) ((1) Harvard-Smithsonian CfA, (2) RIKEN CCS)

Comments: 14 pages, 13 figures, 4 tables. Matches accepted MNRAS version

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

[74]  arXiv:1910.10580 (replaced) [pdf, ps, other]

Title: Standard Sirens as a novel probe of dark energy

Authors: William J. Wolf, Macarena Lagos

Comments: Updated to published version

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

[75]  arXiv:1910.11167 (replaced) [pdf, other]

Title: Spiral structure generated by major planets in proto-planetary disks: the role of periodic orbits near resonance

Authors: R.H. Sanders

Comments: 14 pages, 10 figures, detailed comparison with observed system added. Minor errors corrected

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

[76]  arXiv:1911.01580 (replaced) [pdf, other]

Title: Polarized primordial gravitational waves in the ghost-free parity-violating gravity

Authors: Jin Qiao, Tao Zhu, Wen Zhao, Anzhong Wang

Comments: 10 pages, 1 figure, Phys.Rev.D accepted

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

[77]  arXiv:1912.02185 (replaced) [pdf, ps, other]

Title: Proton-synchrotron as the radiation mechanism of the prompt emission of GRBs?

Authors: G. Ghisellini (1), G. Ghirlanda (1), G. Oganesyan (2,3,4), S. Ascenzi (1), L. Nava (1,5,6,7), A. Celotti (8,1,6,7), O.S. Salafia (1), E.M. Ravasio (1,9), M. Ronchi (1) (1:OA Brera, 2: GSSI, 3: INFN L'Aquila, 4: OA Teramo, 5: OA Trieste, 6: INFN 7: IFPU Trieste, 8: SISSA Trieste, 9: Univ. Bicocca Milano)

Comments: 7 pages, 3 figures, accepted for publication in A&A

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

[78]  arXiv:1912.04167 (replaced) [pdf, ps, other]

Title: KIC 8840638: A high mass-ratio eclipsing binary consisting of a $δ$ Scuti star with multiperiodic pulsations

Authors: Tao-Zhi Yang, Zhaoyu Zuo, Junhui Liu

Comments: Submitted to ApJ, comments are welcomed

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

[79]  arXiv:1912.04188 (replaced) [pdf, other]

Title: Connection between $νn \rightarrow \barν \bar{n}$ reactions and $n$-$\bar{n}$ oscillations via additional Higgs triplets

Authors: Yongliang Hao

Comments: 14 pages, 6 figures, and 3 tables (minor changes)

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

[80]  arXiv:1912.08150 (replaced) [pdf, ps, other]

Title: Nonlinear scattering of Fast Radio Bursts

Authors: Andrei Gruzinov

Comments: 5 pages, 2 figures, glaring misinterpretation of observations removed

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

[81]  arXiv:1912.09081 (replaced) [pdf, other]

Title: Fast Luminous Blue Transients in the Reionization Era and Beyond

Authors: Tomoki Terasaki, Daichi Tsuna, Toshikazu Shigeyama

Comments: 6 pages, 5 figures added discussion in Sec 4

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

[82]  arXiv:2001.00085 (replaced) [pdf, other]

Title: How surfaces shape the climate of habitable exoplanets

Authors: Jack Madden, Lisa Kaltenegger

Comments: Accepted to MNRAS Feb. 5, 2020 - 12 pages, 10 figures

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

[83]  arXiv:2001.00695 (replaced) [pdf, other]

Title: Evidence against Ryskin's model of cosmic acceleration

Authors: Joseph Ryan

Comments: Accepted for publication in Astroparticle Physics, copyright 2020. This manuscript version is made available under the CC-BY-NC-ND 4.0 license this http URL

Journal-ref: Astropart. Phys. 118 (2020) 102428

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

[84]  arXiv:2001.08422 (replaced) [pdf, other]

Title: In-situ switchback formation in the expanding solar wind

Authors: Jonathan Squire, Benjamin D. G. Chandran, Romain Meyrand

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

[85]  arXiv:2001.11045 (replaced) [pdf, other]

Title: Hints on the origins of particle traps in protoplanetary disks given by the $M_{\rm{dust}}-M_{\star}$ relation

Authors: Paola Pinilla, Ilaria Pascucci, Sebastian Marino

Comments: Accepted for publication in A&A, minor changes after language edition

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

[86]  arXiv:2001.11519 (replaced) [pdf, other]

Title: The OTELO survey. I. Description, data reduction, and multi-wavelength catalogue

Authors: Ángel Bongiovanni, Marina Ramón-Pérez, Ana Mará Pérez García, Jordi Cepa, Miguel Cerviño, Jakub Nadolny, Ricardo Pérez Martínez, Emilio J. Alfaro Navarro, Héctor O. Castañeda, José Antonio de Diego, Alessandro Ederoclite, Mirian Fernández-Lorenzo, Jesús Gallego, J. Jesús González, J. Ignacio González-Serrano, Maritza A. Lara-López, Iván Oteo Gómez, Carmen P. Padilla Torres, Irene Pintos-Castro, Mirjana Pović, Miguel Sánchez-Portal, D. Heath Jones, Joss Bland-Hawthorn, Antonio Cabrera-Lavers

Comments: v1: 29 pages, 29 figures. Published in Astronomy \& Astrophysics. v2: author's affiliation and final statement in Abstract updated

Journal-ref: A&A, 631A (2019), 9B

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

[87]  arXiv:2002.00972 (replaced) [pdf, other]

Title: What do observations tell us about the highest-redshift supermassive black holes?

Authors: Benny Trakhtenbrot

Comments: 13 pages of text, 6 figures. Invited review talk at IAU Symposium 356, "Nuclear Activity in Galaxies across Cosmic Time", Oct 2019

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

[88]  arXiv:2002.01756 (replaced) [pdf, ps, other]

Title: N=2 PNGB Quintessence Dark Energy

Authors: Keunsu Cheon, Jungjai Lee

Comments: 6 pages, 2 figures, minor revision

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

[89]  arXiv:2002.01807 (replaced) [pdf, other]

Title: ISPY -- NACO Imaging Survey for Planets around Young stars: Survey description and results from the first 2.5 years of observations

Authors: R. Launhardt, Th. Henning, A. Quirrenbach, D. Ségransan, H. Avenhaus, R. van Boekel, S. S. Brems, A. C. Cheetham, G. Cugno, J. Girard, N. Godoy, G. M. Kennedy, A.-L. Maire, S. Metchev, A. Müller, A. Musso Barcucci, J. Olofsson, F. Pepe, S. P. Quanz, D. Queloz, S. Reffert, E. L. Rickman, H. L. Ruh, M. Samland

Comments: 25 pages, 14 figures

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

[90]  arXiv:2002.01941 (replaced) [pdf, other]

Title: The formation of exponential disk galaxies in MOND

Authors: Nils Wittenburg, Pavel Kroupa, Benoit Famaey

Comments: 58 pages, 59 figures, 7 tables; accepted for publication in ApJ 18.01.2020; For movies of the formation of these galaxies see Youtube entry:"Formation of disk galaxies in MOND by Nils Wittenburg"

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

[91]  arXiv:2002.01956 (replaced) [pdf, other]

Title: Constraining the Mass of the Emerging Galaxy Cluster SpARCS1049+56 at z=1.71 with Infrared Weak Lensing

Authors: Kyle Finner, M. James Jee, Tracy Webb, Gillian Wilson, Saul Perlmutter, Adam Muzzin, Julie Hlavacek-Larrondo

Comments: 13 pages, 7 figures, submitted to ApJ

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

• New submissions
• Cross-lists
• Replacements