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New submissions for Wed, 18 Mar 20

[1]  arXiv:2003.07358 [pdf, other]

Title: Parallel faceted imaging in radio interferometry via proximal splitting (Faceted HyperSARA): when precision meets scalability

Authors: Pierre-Antoine Thouvenin, Abdullah Abdulaziz, Ming Jiang, Arwa Dabbech, Audrey Repetti, Adrian Jackson, Jean-Philippe Thiran, Yves Wiaux

Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Image and Video Processing (eess.IV); Signal Processing (eess.SP)

Upcoming radio interferometers are aiming to image the sky at new levels of resolution and sensitivity, with wide-band image cubes reaching close to the Petabyte scale for SKA. Modern proximal optimization algorithms have shown a potential to significantly outperform CLEAN thanks to their ability to inject complex image models to regularize the inverse problem for image formation from visibility data. They were also shown to be scalable to large data volumes thanks to a splitting functionality enabling the decomposition of data into blocks, for parallel processing of block-specific data-fidelity terms of the objective function. In this work, the splitting functionality is further exploited to decompose the image cube into spatio-spectral facets, and enable parallel processing of facet-specific regularization terms in the objective. The resulting Faceted HyperSARA algorithm is implemented in MATLAB (code available on GitHub). Simulation results on synthetic image cubes confirm that faceting can provide a major increase in scalability at no cost in imaging quality. A proof-of-concept reconstruction of a 15 GB image of Cyg A from 7.4 GB of VLA data, utilizing 496 CPU cores on a HPC system for 68 hours, confirms both scalability and a quantum jump in imaging quality from CLEAN. Assuming slow spectral slope of Cyg A, we also demonstrate that Faceted HyperSARA can be combined with a dimensionality reduction technique, enabling utilizing only 31 CPU cores for 142 hours to form the Cyg A image from the same data, while preserving reconstruction quality. Cyg A reconstructed cubes are available online.

[2]  arXiv:2003.07362 [pdf, other]

Title: Setting the Stage for Cosmic Chronometers. II. Impact of Stellar Population Synthesis Models Systematics and Full Covariance Matrix

Authors: Michele Moresco, Raul Jimenez, Licia Verde, Andrea Cimatti, Lucia Pozzetti

Comments: 20 pages, 9 figures. Submitted to ApJ

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

The evolution of differential ages of passive galaxies at different redshifts (cosmic chronometers) has been proved to be a method potentially able to constrain the Hubble parameter in a cosmology-independent way, but the systematic uncertainties must be carefully evaluated. In this paper, we compute the contribution to the full covariance matrix of systematic uncertainties due to the choice of initial mass function, stellar library, and metallicity, exploring a variety of stellar population synthesis models; the effect of a residual young component and star formation history was discussed elsewhere. Through simulations in the redshift range 0<z<1.5 we find that the choice of the stellar population synthesis model dominates the total error budget on H(z), with contributions at ~4.5% level, discarding the most discordant model. The contribution due to the choice of initial mass function is <0.5%, while that due to the stellar library is ~6.6% on average. In parallel, we also assess the impact of an uncertainty in the determination of the stellar metallicity, finding that an error of ~10% (5%) on the stellar metallicity propagates to a 9% (4%) error on H(z). These results are used to provide the combined contribution of these systematic effects on the error budget. For current H(z) measurements, where the uncertainties due to metallicity and star formation history were already included, we show that, using the more modern stellar libraries, the additional systematic uncertainty is between 5.4% (at z=0.2) and 2.3% (at z=1.5). To reach the goal of keeping the systematic error budget below the 1% level we discuss that efforts needed to obtain higher resolution and signal-to-noise spectra and improvements in the modeling of stellar population synthesis.

[3]  arXiv:2003.07364 [pdf, other]

Title: Clustering of Local Extrema in Planck CMB maps

Authors: A. Vafaei Sadr, S. M. S. Movahed

Comments: 16 pages, 19 figures

Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Astrophysical Phenomena (astro-ph.HE); Instrumentation and Methods for Astrophysics (astro-ph.IM); Applications (stat.AP); Computation (stat.CO)

The clustering of local extrema including peaks and troughs will be exploited to assess Gaussianity, asymmetry and the footprint of cosmic strings network on the CMB random field observed by {\it Planck} satellite. The number density of local extrema reveals some non-resolved shot noise in {\it Planck} maps. The \texttt{SEVEM} data has maximum number density of peaks, $n_{pk}$, and troughs, $n_{tr}$, compared to other observed maps. The cumulative of $n_{pk}$ and $n_{tr}$ above and below a threshold, $\vartheta$, for all {\it Planck} maps except for the 100GHz band are compatible with the Gaussian random field. The unweighted Two-Point Correlation Function (TPCF), $\Psi(\theta;\vartheta)$, of the local extrema illustrates significant non-Gaussianity for angular separation $\theta\le 15'$ for all available thresholds. Our results show that to put the feasible constraint on the amplitude of the mass function based on the value of $\Psi$ around the {\it Doppler peak} ($\theta\approx 70'-75'$), we should consider $\vartheta\gtrsim+1.0$. The scale independent bias factors for peak above a threshold for large separation angle and high threshold level are in agreement with that of expected for a pure Gaussian CMB. Unweighted TPCF of local extrema demonstrates a level of rejecting Gaussian hypothesis in \texttt{SMICA}. Genus topology also confirms the Gaussian hypothesis for different component separation maps. Tessellating CMB map with disk of size $6^{\circ}$ based on $n_{pk}$ and $\Psi_{pk-pk}$ demonstrate statistical symmetry in {\it Planck} maps. Combining all maps and applying the $\Psi_{pk-pk}$ puts the upper bound on the cosmic string's tension: $G\mu^{(up)} \lesssim 5.00\times 10^{-7}$.

[4]  arXiv:2003.07365 [pdf, other]

Title: Changing look quasars from tidal disruption flares

Authors: Hamsa Padmanabhan (CITA), Abraham Loeb (Harvard)

Comments: 5 pages, 6 figures

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

We explore the contributions of Tidal Disruption Events (TDEs) as potential triggers for Active Galactic Nuclei (AGN). Using the latest data available from X-ray and optical observations of high-redshift galaxies, as well as the evolution of their central supermassive black holes, we calculate the extent to which TDEs trigger AGN as a function of their luminosities. We find that at low redshifts ($z < 1$), a few percent of all AGN with bolometric luminosities $L_{\rm Bol} \lesssim 10^{44}$ erg s$^{-1}$ may be attributable to TDE triggers. However, this fraction can significantly increase at earlier cosmic times, reaching several tens of percent at $z > 2$, including about 20-50% of the observed population of Changing Look Quasars (CLQs). TDEs may comprise a significant fraction of the Compton-Thick (CT) AGN population at $z > 2$. The above findings motivate further calibration from upcoming X-ray missions and spectroscopic surveys targeting TDE-AGN.

[5]  arXiv:2003.07367 [pdf, other]

Title: Euclid: The selection of quiescent and star-forming galaxies using observed colours

Authors: L. Bisigello, U. Kuchner, C.J. Conselice, S. Andreon, M. Bolzonella, P.-A. Duc, B. Garilli, A. Humphrey, C. Maraston, M. Moresco, L. Pozzetti, C. Tortora, G. Zamorani, N. Auricchio, J. Brinchmann, V. Capobianco, J. Carretero, F.J. Castander, M. Castellano, S. Cavuoti, A. Cimatti, R. Cledassou, G. Congedo, L. Conversi, L. Corcione, M.S. Cropper, S. Dusini, M. Frailis, E. Franceschi, P. Franzetti, M. Fumana, F. Hormuth, H. Israel, K. Jahnke, S. Kermiche, T. Kitching, R. Kohley, B. Kubik, M. Kunz, O. Le Fèvre, S. Ligori, P.B. Lilje, I. Lloro, E. Maiorano, O. Marggraf, R. Massey, D.C. Masters, S. Mei, Y. Mellier, G. Meylan, C. Padilla, S. Paltani, F. Pasian, V. Pettorino, S. Pires, G. Polenta, M. Poncet, F. Raison, J. Rhodes, M. Roncarelli, E. Rossetti, R. Saglia, M. Sauvage, P. Schneider, et al. (10 additional authors not shown)

Comments: 19 pages, 15 figures, 5 tables, accepted for publication in MNRAS

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

The Euclid mission will observe well over a billion galaxies out to $z\sim6$ and beyond. This will offer an unrivalled opportunity to investigate several key questions for understanding galaxy formation and evolution. The first step for many of these studies will be the selection of a sample of quiescent and star-forming galaxies, as is often done in the literature by using well known colour techniques such as the `UVJ' diagram. However, given the limited number of filters available for the Euclid telescope, the recovery of such rest-frame colours will be challenging. We therefore investigate the use of observed Euclid colours, on their own and together with ground-based u-band observations, for selecting quiescent and star-forming galaxies. The most efficient colour combination, among the ones tested in this work, consists of the (u-VIS) and (VIS-J) colours. We find that this combination allows users to select a sample of quiescent galaxies complete to above $\sim70\%$ and with less than 15$\%$ contamination at redshifts in the range $0.75<z<1$. For galaxies at high-z or without the u-band complementary observations, the (VIS-Y) and (J-H) colours represent a valid alternative, with $>65\%$ completeness level and contamination below 20$\%$ at $1<z<2$ for finding quiescent galaxies. In comparison, the sample of quiescent galaxies selected with the traditional UVJ technique is only $\sim20\%$ complete at $z<3$, when recovering the rest-frame colours using mock Euclid observations. This shows that our new methodology is the most suitable one when only Euclid bands, along with u-band imaging, are available.

[6]  arXiv:2003.07371 [pdf, other]

Title: A pulsating white dwarf in an eclipsing binary

Authors: Steven G. Parsons, Alexander J. Brown, Stuart P. Littlefair, Vikram S. Dhillon, Thomas R. Marsh, J. J. Hermes, Alina G. Istrate, Elmé Breedt, Martin J. Dyer, Matthew J. Green, David I. Sahman

Comments: Accepted for publication in Nature Astronomy

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

White dwarfs are the burnt out cores of Sun-like stars and are the final fate of 97% of all stars in our Galaxy. The internal structure and composition of white dwarfs are hidden by their high gravities, which causes all elements, apart from the lightest ones, to settle out of their atmospheres. The most direct method to probe the inner structure of stars and white dwarfs in detail is via asteroseismology. Here we present the first known pulsating white dwarf in an eclipsing binary system, enabling us to place extremely precise constraints on the mass and radius of the white dwarf from the light curve, independent of the pulsations. This 0.325M$_\odot$ white dwarf --- one member of SDSS J115219.99+024814.4 --- will serve as a powerful benchmark to constrain empirically the core composition of low-mass stellar remnants and investigate the effects of close binary evolution on the internal structure of white dwarfs.

[7]  arXiv:2003.07377 [pdf, other]

Title: Dynamics of DiskMass Survey Galaxies in $Refracted$ $Gravity$

Authors: Valentina Cesare, Antonaldo Diaferio, Titos Matsakos, Garry Angus

Comments: 36 pages, 22 figures, accepted on March 10 2020 in Astronomy & Astrophysics, Section 2. Astrophysical processes of Astronomy and Astrophysics

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

We test if Refracted Gravity (RG) can describe the dynamics of disk galaxies without resorting to dark matter. RG is a classical theory of gravity where the standard Poisson equation is modified by the gravitational permittivity, $\epsilon$, a universal monotonic function of the local mass density. We use the rotation curves and the vertical velocity dispersions of 30 galaxies in the DiskMass Survey (DMS) to determine $\epsilon$. RG describes the kinematic profiles with mass-to-light ratios in agreement with SPS models, and disk thicknesses in agreement with observations, once observational biases are considered. Our results rely on setting the three free parameters of RG for each galaxy. However, we show that the differences of these parameters from galaxy to galaxy could be ascribed to statistical fluctuations. We adopt an approximate method to find a single set of parameters that might properly describe the kinematics of the entire sample and suggest the universality of $\epsilon$. We finally show that the RG models of the individual rotation curves can only partly describe the radial acceleration relation (RAR). Evidently, the RG models underestimate the observed accelerations by 0.1-0.3 dex at low Newtonian accelerations. Another problem is the strong correlations, at largely more than 5$\sigma$, between the residuals of the RAR models and three radially-dependent properties of galaxies, whereas the DMS data show considerably less significant correlations, at more than 4$\sigma$, for only two of them. These correlations might originate the non-null intrinsic scatter of the RG models, at odds with the observed intrinsic scatter of galaxy samples, different from DMS, which is consistent with 0. Further studies are required to assess if these discrepancies in the RAR originate from the DMS sample, which might not be ideal for deriving the RAR, or if they are genuine failures of RG.

[8]  arXiv:2003.07379 [pdf, other]

Title: The Differences between Analytical and Numerical Ignition Curve and its possible effects on Hydrodynamics of Ignited He-C-O Mixture

Authors: Rahul Kashyap

Comments: Comments are invited

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

In this paper, we use large reaction networks to find ignition conditions of single-zone nuclear fuel with compositions typical of white dwarf (WD) matter. The necessary but, possibly not sufficient condition for initiation of detonation is that the nuclear burning proceeds on smaller timescale than the sound-crossing timescale. Under typical white dwarf thermodynamic conditions, the nuclear timescale depends sensitively on the chosen nuclear reaction network, and widely-used analytical formulae are not sufficient to accurately determine unstable ignition conditions the answer to which lies in the fully compressible turbulent simulations. We model the nuclear reactions in the numerical simulation using the astrophysical code TORCH. We report the differences introduced because of the choice of the size of the nuclear reaction network. Our findings have implications for numerical results obtained using the widely-used 19-species network in multidimensional simulations of WD of Chandrasekhar and sub-Chandrasekhar masses. We present a sufficiently accurate general criterion in temperature-density ($T-\rho$) plane for a given initial fuel to ignite in an unstable fashion.

[9]  arXiv:2003.07387 [pdf, other]

Title: Fast simulations of cosmic large-scale structure with massive neutrinos

Authors: Christian Partmann, Christian Fidler, Cornelius Rampf, Oliver Hahn

Comments: 23 pages, 9 figures, see Fig. 6 for the power suppression plot

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

Accurate cosmological simulations that include the effect of non-linear matter clustering as well as of massive neutrinos are essential for measuring the neutrino mass scale from upcoming galaxy surveys. Typically, Newtonian simulations are employed and the neutrino distribution is sampled with a large number of particles in order to beat down the shot noise. Here we perform very efficient simulations with light massive neutrinos which require virtually no extra cost over matter-only simulations, and furthermore do not require tracer particles for the neutrinos. Instead, we use a weak-field dictionary based on the recently developed Newtonion motion approach, where Newtonian simulations for matter are paired with a linear relativistic Boltzmann code to allow for an absorption of the neutrino evolution into a time-dependent coordinate transformation. For this, only minimal modifications in existing N-body codes are required, which we have explicitly implemented in $\textit{gevolution}$ and $\textit{gadget-2}$. Our fast method determines the non-linear matter power spectrum to permille-level precision when compared against state-of-the-art simulations that have been performed for $0.1\,{\rm eV} \leq \sum m_\nu \leq 0.3\,$eV.

[10]  arXiv:2003.07390 [pdf, ps, other]

Title: Facing the problems on the determination of stellar temperatures and gravities: Galactic globular clusters

Authors: A. Mucciarelli, P. Bonifacio

Comments: accepted for publication in A&A, 12 pages, 9 figures, 4 tables

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

We analysed red giant branch stars in 16 Galactic globular clusters, computing their atmospheric parameters both from the photometry and from excitation and ionisation balances. The spectroscopic parameters are lower than the photometric ones and this discrepancy increases decreasing the metallicity, reaching, at [Fe/H]~-2.5 dex, differences of ~350 K in effective temperature and ~1 dex in surface gravity. We demonstrate that the spectroscopic parameters are inconsistent with the position of the stars in the colour-magnitude diagram, providing too low temperatures and gravities, and predicting that the stars are up to about 2.5 magnitudes brighter than the observed magnitudes. The parameter discrepancy is likely due to the inadequacies of the adopted physics, in particular the assumption of 1-dimensional geometry can be the origin of the observed slope between iron abundances and excitation potential that leads to low temperatures. However, the current modelling of 3D/NLTE radiative transfer for giant stars seems to be not able to totally erase this slope. We conclude that the spectroscopic parameters are wrong for metallicity lower than -1.5 dex and for these red giant stars photometric temperatures and gravities should be adopted. We provide a simple relation to correct the spectroscopic temperatures in order to put them onto a photometric scale.

[11]  arXiv:2003.07409 [pdf, other]

Title: Fingerprints of binary black hole formation channels encoded in the mass and spin of merger remnants

Authors: Manuel Arca Sedda, Michela Mapelli, Mario Spera, Matthew Benacquista, Nicola Giacobbo

Comments: Resubmitted to ApJ after favourable referee report: 25 pages, 13 figures, 2 tables

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

Binary black holes (BBHs) are thought to form in different environments, including the galactic field and (globular, nuclear, young and open) star clusters. Here, we propose a method to estimate the fingerprints of the main BBH formation channels associated with these different environments. We show that the metallicity distribution of galaxies in the local Universe along with the relative amount of mergers forming in the field or in star clusters determine the main properties of the BBH population. Our fiducial model predicts that the heaviest merger to date, GW170729, originated from a progenitor that underwent 2--3 merger events in a dense star cluster, possibly a galactic nucleus. The model predicts that at least one merger remnant out of 100 BBH mergers in the local Universe has mass $90 < M_{\rm rem}/ {\rm ~M}_\odot \leq{} 110$, and one in a thousand can reach a mass as large as $M_{\rm rem} \gtrsim 250$ M$_\odot$. Such massive black holes would bridge the gap between stellar-mass and intermediate-mass black holes. The relative number of low- and high-mass BBHs can help us unravelling the fingerprints of different formation channels. Based on the assumptions of our model, we expect that isolated binaries are the main channel of BBH merger formation if $\sim 70\%$ of the whole BBH population has remnants masses $<50$ M$_\odot$, whereas $\gtrsim{}6$\% of remnants with masses $>75$ M$_\odot$ point to a significant sub-population of dynamically formed BBH binaries.

[12]  arXiv:2003.07423 [pdf, ps, other]

Title: Exploring molecular complexity with ALMA (EMoCA): Complex isocyanides in Sgr B2(N)

Authors: E. R. Willis (1), R. T. Garrod (1 and 2), A. Belloche (3), H. S. P. Müller (4), C. J. Barger (1), M. Bonfand (3), K. M. Menten (3) ((1) Department of Chemistry, University of Virginia, (2) Department of Astronomy, University of Virginia, (3) Max-Planck-Institut für Radioastronomie, (4) I. Physikalisches Institut, Universit ät zu Köln)

Comments: 29 pages, 24 figures, accepted for publication in Astronomy & Astrophysics

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

We used the EMoCA survey data to search for isocyanides in Sgr B2(N2) and their corresponding cyanide analogs. We then used the coupled three-phase chemical kinetics code MAGICKAL to simulate their chemistry. Several new species, and over 100 new reactions have been added to the network. In addition, a new single-stage simultaneous collapse/warm-up model has been implemented, thus eliminating the need for the previous two-stage models. A variable, visual extinction-dependent $\zeta$ was also incorporated into the model and tested. We report the tentative detection of CH$_3$NC and HCCNC in Sgr B2(N2), which represents the first detection of both species in a hot core of Sgr B2. Our updated chemical models can reproduce most observed NC:CN ratios reasonably well depending on the physical parameters chosen. The model that performs best has an extinction-dependent cosmic-ray ionization rate that varies from ~2 $\times$ 10$^{-15}$ s$^{-1}$ at the edge of the cloud to ~1 $\times$ 10$^{-16}$ s$^{-1}$ in the center. Models with higher extinction-dependent $\zeta$ than this model generally do not agree as well, nor do models with a constant $\zeta$ greater than the canonical value of 1.3 $\times$ 10$^{-17}$ s$^{-1}$ throughout the source. Radiative transfer models are run using results of the best-fit chemical model. Column densities produced by the radiative transfer models are significantly lower than those determined observationally. Inaccuracy in the observationally determined density and temperature profiles is a possible explanation. Excitation temperatures are well reproduced for the true ``hot core'' molecules, but are more variable for other molecules such as HC$_3$N, for which fewer lines exist in ALMA Band 3.

[13]  arXiv:2003.07446 [pdf, other]

Title: The Low Earth Orbit Satellite Population and Impacts of the SpaceX Starlink Constellation

Authors: Jonathan C. McDowell

Comments: 20 pages, 14 figures. Accepted for publication in Ap J Letters

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

I discuss the current low Earth orbit artificial satellite population and show that the proposed `megaconstellation' of circa 12,000 Starlink internet satellites would dominate the lower part of Earth orbit, below 600 km, with a latitude-dependent areal number density of between 0.005 and 0.01 objects per square degree at airmass < 2. Such large, low altitude satellites appear visually bright to ground observers, and the initial Starlinks are naked eye objects. I model the expected number of illuminated satellites as a function of latitude, time of year, and time of night and summarize the range of possible consequences for ground-based astronomy. In winter at lower latitudes typical of major observatories, the satellites will not be illuminated for six hours in the middle of the night. However, at low elevations near twilight at intermediate latitudes (45-55 deg, e.g. much of Europe) hundreds of satellites may be visible at once to naked-eye observers at dark sites.

[14]  arXiv:2003.07447 [pdf]

Title: Cryogenic-specific reddish coloration by cryoplasma: New explanation to color diversity of outer solar system objects

Authors: Noritaka Sakakibara, Yu Yu Phua, Tsuyohito Ito, Kazuo Terashima

Comments: 31 pages, 13 figures, published in ApJL on March 16, 2020

Journal-ref: ApJL 891 (2020) L44

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

Reddish coloration and color diversity among icy bodies in the outer solar system are one of the significant clues for understanding the status and history of the solar system. However, the origin of color distribution remains debatable. Here, we demonstrate reddish coloration that is stable only at cryogenic temperatures in a laboratory experiment. The reddish coloration was produced on methanol- and water-containing ice irradiated with nitrogen-containing cryoplasma at 85 K. The reddish color visually faded and disappeared at 120-150 K as the ice was heated, unlike well-known refractory organic tholins that are stable even when heated to room temperature. This temperature dependence of reddish coloration under cryogenic conditions could provide a new possible explanation for the absence of ultra-red coloration closer to the Sun in the outer solar system. Our result implies that a reddish material specific to cryogenic environments is useful for the investigation of color diversity and formation mechanism of the outer solar system.

[15]  arXiv:2003.07455 [pdf, ps, other]

Title: A first meta-analysis of barred galaxies with direct bar pattern speed measurements

Authors: Virginia Cuomo, J. Alfonso L. Aguerri, Enrico Maria Corsini, Victor P. Debattista

Comments: submitted to Astronomy & Astrophysics

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

We investigate the relations between the properties of bars and their host galaxies in a sample of 104 nearby barred galaxies, spanning a wide range of morphological types and luminosities. The sample includes all the galaxies with direct measurement of their bar pattern speed based on long-slit or integral-field stellar spectroscopy using the Tremaine-Weinberg method. For each galaxy, we collected the radius, strength, pattern speed, corotation radius, and rotation rate for the bar and we considered the Hubble type and absolute SDSS $r$-band magnitude of the host galaxy. We also derived the bulge-to-total luminosity ratio for a subsample of 34 galaxies with an available photometric decomposition. We limited our analysis to the galaxies with a relatively small relative error on the bar pattern speed ($<50$ per cent) and not hosting an ultrafast bar. The final sample consists of 77 objects, with 34 SB0-SBa and 43 SBab-SBc galaxies. We confirmed earlier observational findings that longer bars rotate with lower bar pattern speeds, shorter bars are weaker, fast bars rotate with higher bar pattern speeds and have smaller corotation radii, and disc-dominated galaxies host weaker bars. In addition, we found that stronger bars rotate with lower bar pattern speeds as predicted for the interchange of angular momentum during bar evolution depending on galaxy properties. Moreover, we report that brighter galaxies host longer bars, which rotate with lower bar pattern speeds and have larger corotation radii. This result, together with the fact that we observe stronger bars in bulge-dominated galaxies, is in agreement with a scenario of downsizing in bar formation and co-evolution of bars and bulges, if more massive galaxies formed earlier and had sufficient time to slow down, grow in length, and push corotation outwards.

[16]  arXiv:2003.07468 [pdf, other]

Title: Implications of the Quantum Noise Target for the Einstein Telescope Infrastructure Design

Authors: Philip Jones, Teng Zhang, Haixing Miao, Andreas Freise

Comments: 8 pages, 12 figures, 3 tables. Submitted to Physical Review D on 2020-03-16

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

The design of a complex instrument such as Einstein Telescope (ET) is based on a target sensitivity derived from an elaborate case for scientific exploration. At the same time it incorporates many trade-off decisions to maximise the scientific value by balancing the performance of the various subsystems against the cost of the installation and operation. In this paper we discuss the impact of a long signal recycling cavity (SRC) on the quantum noise performance. We show the reduction in sensitivity due to a long SRC for an ET high-frequency interferometer, provide details on possible compensations schemes and suggest a reduction of the SRC length. We also recall details of the trade-off between the length and optical losses for filter cavities, and show the strict requirements for an ET low-frequency interferometer. Finally, we present an alternative filter cavity design for an ET low-frequency interferometer making use of a coupled cavity, and discuss the advantages of the design in this context.

[17]  arXiv:2003.07471 [pdf, other]

Title: The CARMENES search for exoplanets around M dwarfs. Radial velocities and activity indicators from cross-correlation functions with weighted binary masks

Authors: M. Lafarga, I. Ribas, C. Lovis, M. Perger, M. Zechmeister, F. F. Bauer, M. Kürster, M. Cortés-Contreras, J. C. Morales, E. Herrero, A. Rosich, D. Baroch, A. Reiners, J. A. Caballer, A. Quirrenbach, P. J. Amado, J. M. Alacid, V. J. S. Béjar, S. Dreizler, A. P. Hatzes, T. Henning, S. V. Jeffers, A. Kaminski, D. Montes, S. Pedraz, C. Rodríguez-López, J. H. M. M. Schmitt

Comments: 24 pages, 14 figures. Accepted for publication in A&A. Code available at this https URL

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

For years, the standard procedure to measure radial velocities (RVs) of spectral observations consisted in cross-correlating the spectra with a binary mask, that is, a simple stellar template that contains information on the position and strength of stellar absorption lines. The cross-correlation function (CCF) profiles also provide several indicators of stellar activity. We present a methodology to first build weighted binary masks and, second, to compute the CCF of spectral observations with these masks from which we derive radial velocities and activity indicators. These methods are implemented in a python code that is publicly available. To build the masks, we selected a large number of sharp absorption lines based on the profile of the minima present in high signal-to-noise ratio (S/N) spectrum templates built from observations of reference stars. We computed the CCFs of observed spectra and derived RVs and the following three standard activity indicators: full-width-at-half-maximum as well as contrast and bisector inverse slope.We applied our methodology to CARMENES high-resolution spectra and obtain RV and activity indicator time series of more than 300 M dwarf stars observed for the main CARMENES survey. Compared with the standard CARMENES template matching pipeline, in general we obtain more precise RVs in the cases where the template used in the standard pipeline did not have enough S/N. We also show the behaviour of the three activity indicators for the active star YZ CMi and estimate the absolute RV of the M dwarfs analysed using the CCF RVs.

[18]  arXiv:2003.07472 [pdf, other]

Title: ALMA high frequency long baseline campaign in 2017: band-to-band phase referencing in submillimeter waves

Authors: Yoshiharu Asaki, Luke T. Maud, Edward B. Fomalont, Neil M. Phillips, Akihiko Hirota, Tsuyoshi Sawada, Loreto Barcos-Muñoz, Anita M. S. Richards, William R. F. Dent, Satoko Takahashi, Stuartt Corder, John M. Carpenter, Eric Villard, Elizabeth M. Humphreys

Comments: 61 pages, 17 figures, 8 tables

Journal-ref: 2020ApJS..247...23A

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

In 2017, an Atacama Large Millimeter/submillimeter Array (ALMA) high-frequency long baseline campaign was organized to test image capabilities with baselines up to 16 km at submillimeter (submm) wavelengths. We investigated image qualities using ALMA receiver Bands 7, 8, 9, and 10 (285-875 GHz) by adopting band-to-band (B2B) phase referencing in which a phase calibrator is tracked at a lower frequency. For B2B phase referencing, it is expected that a closer phase calibrator to a target can be used, comparing to standard in-band phase referencing. In the first step, it is ensured that an instrumental phase offset difference between low- and high-frequency Bands can be removed using a differential gain calibration in which a phase calibrator is certainly detected while frequency switching. In the next step, comparative experiments are arranged to investigate the image quality between B2B and in-band phase referencing with phase calibrators at various separation angles. In the final step, we conducted long baseline imaging tests for a quasar at 289 GHz in Band 7 and 405 GHz in Band 8 and complex structure sources of HL Tau and VY CMa at ~670 GHz in Band 9. The B2B phase referencing was successfully applied, allowing us to achieve an angular resolution of 14x11 and 10x8 mas for HL Tau and VY CMa, respectively. There is a high probability of finding a low-frequency calibrator within 5.4 deg in B2B phase referencing, bright enough to use an 8 s scan length combined with a 7.5 GHz bandwidth.

[19]  arXiv:2003.07476 [pdf, ps, other]

Title: SuperModel Predictions in the Outskirts of the Galaxy Cluster Zwicky 3146

Authors: Roberto Fusco-Femiano

Comments: 8 pages, 5 figures, in press on MNRAS

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

The relaxed galaxy cluster Zwicky 3146 is analyzed via the SuperModel, a tool already tested on many clusters since 2009. In particular, this analysis is focused on the intracluster medium X-ray temperature data measured by XMM-Newton up to r_{500}. A previous analysis was based on the temperature profile derived from the Sunyaev-Zeldovich effect pressure data. The gas mass fraction f_{gas} is obtained from the resulting SuperModel temperature profile extrapolated up to the virial radius R, that turns out in agreement with the steep temperature profiles observed by Suzaku, and from the gas density profile observed by XMM-Newton. The comparison between f_{gas} with the universal value indicates a non-thermal pressure component, p_{nth}, in the cluster outskirts. The SuperModel analysis shows a ratio alpha(R) (about 50%) of p_{nth} to the total pressure greater than the values found by simulations, highlighting the possible presence of accreting substructures and inhomogeneities in the gas density profile. Once that this profile is corrected for clumpiness, the level of p_{nth} is considerably reduced. However, a significant turbulence (alpha(R) about 20%) and entropy flattening are still present in the outskirts of the galaxy cluster Zwicky 3146.

[20]  arXiv:2003.07509 [pdf, ps, other]

Title: Tidal and general relativistic effects in rocky planet formation at the sub-stellar mass limit using N-body simulations

Authors: M.B. Sánchez, G.C. de Elía, J.J. Downes

Comments: 16 pages, 17 figures

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

Recent observational results show that very low mass stars and brown dwarfs are able to host close-in rocky planets. Low-mass stars are the most abundant stars in the Galaxy and the formation efficiency of their planetary systems is relevant in the computation of a global probability of finding Earth-like planets inside habitable zones. Tidal forces and relativistic effects are relevant in the latest dynamical evolution of planets around low-mass stars and their effect on the planetary formation efficiency still needs to be addressed. Our goal is to evaluate the impact of tidal forces and relativistic effects on the formation of rocky planets around a star close to the sub-stellar mass limit, in terms of the resulting planetary architectures and its distribution according to the corresponding evolving habitable zone. Thus, we performed a set of $N$-body simulations spanning the first 100~Myr of the evolution of two systems composed respectively by 224 embryos with a total mass 0.25M$_\oplus$ and 74 embryos with a total mass 3 M$_\oplus$ around a central object of 0.08~M$_\odot$. For both scenarios, we compared the planetary architectures that result from simulations that are purely gravitational with those from simulations that include the early contraction and spin-up of the central object, the distortions and dissipation tidal terms and general relativistic effects. We found that the inclusion of these effects allows the formation and survival of a close-in population located in the habitable zone of the system. Thus, both effects are relevant during the formation of rocky planet and their early evolution around stars close to the sub-stellar mass limit, in particular when low-mass planetary embryos are involved.

[21]  arXiv:2003.07569 [pdf, ps, other]

Title: Pulsed fraction of super-critical column accretion flows onto neutron stars: modeling of ultraluminous X-ray pulsars

Authors: Akihiro Inoue, Ken Ohsuga, Tomohisa Kawashima

Comments: 10 pages, 8 figures, accepted for publication in PASJ

Journal-ref: PASJ (2020) psaa010

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

We calculate the pulsed fraction (PF) of the super-critical column accretion flows onto magnetized neutron stars (NSs), of which the magnetic axis is misaligned with the rotation axis, based on the simulation results by Kawashima et al.(2016, PASJ, 68, 83). Here, we solve the geodesic equation for light in the Schwarzschild spacetime in order to take into account the light bending effect. The gravitational redshift and the relativistic doppler effect from gas motions of the accretion columns are also incorporated. The pulsed emission appears since the observed luminosity, which exceeds the Eddington luminosity for the stellar-mass black holes, periodically changes via precession of the column caused by the rotation of the NS. The PF tends to increase as $\theta_{\rm obs}$ approaching to $\theta_{\rm B}$, where $\theta_{\rm obs}$ and $\theta_{\rm B}$ are the observer's viewing angle and the polar angle of the magnetic axis measured from the rotation axis. The maximum PF is around 50 %. Also, we find that the PF becomes less than 5 % for $\theta_{\rm obs} \lesssim 5^\circ$ or for $\theta_{\rm B} \lesssim 5^\circ$. Our results are consistent with observations of ultraluminous X-ray pulsars (ULXPs) with few exceptions, since the ULXPs mostly exhibit the PF of $\lesssim$ 50 %. Our present study supports the hypothesis that the ULXPs are powered by the super-critical column accretion onto NSs.

[22]  arXiv:2003.07572 [pdf, other]

Title: The key role of magnetic fields in binary neutron star mergers

Authors: Riccardo Ciolfi

Comments: Invited review for the Topical Collection on BNS mergers of the journal General Relativity and Gravitation; 28 pages, 7 figures, matching version submitted on February 29th 2020

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

The first multimessenger observation of a binary neutron star (BNS) merger in August 2017 demonstrated the huge scientific potential of these extraordinary events. This breaktrough led to a number of discoveries, including the proof that BNS mergers can launch short gamma-ray burst (SGRB) jets and are responsible for a copious production of heavy r-process elements. On the other hand, the details of the merger and post-merger dynamics remain only poorly constrained, leaving behind important open questions. Numerical relativity simulations are a powerful tool to unveil the physical processes at work in a BNS merger and as such they offer the best chance to improve our ability to interpret the corresponding gravitational wave (GW) and electromagnetic emission. Here, we review the current theoretical investigation on BNS mergers based on general relativistic magnetohydrodynamics simulations, paying special attention to the magnetic field as a crucial ingredient. First, we discuss the evolution, amplification, and emerging structure of magnetic fields in BNS mergers. Then, we consider their impact on various critical aspects: (i) jet formation and the connection with SGRBs, (ii) matter ejection, r-process nucleosynthesis, and radiocatively-powered kilonova transients, and (iii) post-merger GW emission.

[23]  arXiv:2003.07576 [pdf, other]

Title: Uniform distribution of the extremely overionized plasma associated with the supernova remnant G359.1-0.5

Authors: Hiromasa Suzuki, Aya Bamba, Rei Enokiya, Hiroya Yamaguchi, Paul P. Plucinsky, Hirokazu Odaka

Comments: 26 pages, 12 figures. Accepted for ApJ

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

We report on the results of our detailed analyses on the peculiar recombining plasma of the supernova remnant (SNR) G359.1$-$0.5, and the interacting CO clouds. Combining {\it Chandra} and {\it Suzaku} data, we estimated the ionization state of the plasma with a careful treatment of the background spectrum. The average spectrum showed a remarkably large deviation of the electron temperature ($\sim$0.17 keV) from the initial temperature ($>$ 16 keV), indicating that the plasma is in a highly recombination-dominant state. On the other hand, the recombination timescale $({\it n_{\rm e} t})$ is comparable to those of the other recombining SNRs ($\sim4.2 \times 10^{11}$ cm$^{-3}$ s). We also searched for spatial variation of the plasma parameters, but found no significant differences.
Using $^{12}$CO($J$=2--1) data obtained with NANTEN2, we found a new, plausible candidate for the interacting CO cloud, which has a line-of-sight velocity of $\sim -$20 km s$^{-1}$. This indicates that the SNR is located at a distance of $\sim$4 kpc, which is the foreground of the Galactic center, as previously reported. The associated CO cloud does not show clear spatial coincidence with the nearby GeV/TeV emission, indicating that the origins of the GeV/TeV emission are likely unrelated to G359.1$-$0.5.

[24]  arXiv:2003.07579 [pdf, ps, other]

Title: Reflection component in the Bright Atoll Source GX 9+9

Authors: R. Iaria, S. M. Mazzola, T. Di Salvo, A. Marino, A. F. Gambino, A. Sanna, A. Riggio, L. Burderi

Comments: 10 pages, 8 figures, accepted by Astronomy & Astrophysics

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

GX 9+9 (4U 1728-16) is a low mass X-ray binary (LMXB) source harboring a neutron star. Although it belongs to the subclass of the bright Atoll sources together with GX 9+1, GX 3+1, and GX 13+1, its broadband spectrum is poorly studied and apparently does not show reflection features in the spectrum.
To constrain the continuum well and verify whether a relativistic smeared reflection component is present, we analyze the broadband spectrum of GX 9+9 using {\it BeppoSAX} and \textit{XMM-Newton} spectra covering the 0.3-40 keV energy band.
We fit the spectrum adopting a model composed of a disk-blackbody plus a Comptonized component whose seed photons have a blackbody spectrum (Eastern Model). A statistically equivalent model is composed of a Comptonized component whose seed photons have a disk-blackbody distribution plus a blackbody that mimics a saturated Comptonization likely associated with a boundary layer (Western model). Other trials did not return a good fit.
The spectrum of GX 9+9 was observed in a soft state and its luminosity is $2.3 \times 10^{37}$ erg s$^{-1}$ assuming a distance to the source of 5 kpc. In the Eastern Model scenario, we find the seed-photon temperature and electron temperature of the Comptonized component to be $1.14^{+0.10}_{-0.07}$ keV and $2.80^{+0.09}_{-0.04}$ keV, respectively, while the optical depth of the Comptonizing corona is $8.9\pm0.4$. The color temperature of the inner accretion disk is $0.86^{+0.08}_{-0.02}$ keV and $0.82 \pm 0.02$ keV for the {\it BeppoSAX} and \textit{XMM-Newton} spectrum, respectively. In the Western Model scenario, instead, we find that the seed-photon temperature is $0.87 \pm 0.07$ keV and $1.01 \pm 0.08$ keV for the {\it BeppoSAX} and \textit{XMM-Newton} spectrum, respectively. (Abridged abstract)

[25]  arXiv:2003.07620 [pdf, other]

Title: CHEOPS observations of TESS primary mission monotransits

Authors: Benjamin F. Cooke (1,2), Don Pollacco (1,2), Monika Lendl (3,4), Thibault Kuntzer (3), Andrea Fortier (5) ((1) Department of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK, (2) Centre for Exoplanets and Habitability, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK, (3) Observatoire de Genève, Université de Genève, 51 Ch. des Maillettes, 1290 Sauverny, Switzerland, (4) Space Research Institute, Austrian Academy of Sciences, Schmiedlstr. 6, 8042 Graz, Austria, (5) Centre for Space and Habitability (CSH), University of Bern, Gesellschaftstrasse 6, CH-3012, Bern, Switzerland)

Comments: 7 pages, 8 figures. Accepted for publication in MNRAS

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

We set out to look at the overlap between CHEOPS sky coverage and TESS primary mission monotransits to determine what fraction of TESS monotransits may be observed by CHEOPS. We carry out a simulation of TESS transits based on the stellar population in TICv8 in the primary TESS mission. We then select the monotransiting candidates and determine their CHEOPS observing potential. We find that TESS will discover approximately 433 monotransits during its primary mission. Using a baseline observing efficiency of 40% we then find that 387 of these ($\sim$89%) will be observable by CHEOPS with an average observing time of $\sim$60 days per year. Based on the individual observing times and orbital periods of each system we predict that CHEOPS could observe additional transits for approximately 302 of the 433 TESS primary mission monotransits ($\sim$70%). Given that CHEOPS will require some estimate of period before observing a target we estimate that up to 250 ($\sim$58%) TESS primary mission monotransits could have solved periods prior to CHEOPS observations using a combination of photometry and spectroscopy.

[26]  arXiv:2003.07627 [pdf, other]

Title: Four direct measurements of the fine-structure constant 13 billion years ago

Authors: Michael R. Wilczynska, John K. Webb, Matthew Bainbridge, Sarah E. I. Bosman, John D. Barrow, Robert F. Carswell, Mariusz P. Dabrowski, Vincent Dumont, Ana Catarina Leite, Chung-Chi Lee, Katarzyna Leszczynska, Jochen Liske, Konrad Marosek, Carlos J.A.P. Martins, Dinko Milakovic, Paolo Molaro, Luca Pasquini

Comments: Accepted for publication in Science Advances

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

Observations of the redshift z=7.085 quasar J1120+0641 have been used to search for variations of the fine structure constant, alpha, over the redshift range 5.5 to 7.1. Observations at z=7.1 probe the physics of the universe when it was only 0.8 billion years old. These are the most distant direct measurements of alpha to date and the first measurements made with a near-IR spectrograph. A new AI analysis method has been employed. Four measurements from the X-SHOOTER spectrograph on the European Southern Observatory's Very Large Telescope (VLT) directly constrain any changes in alpha relative to the value measured on Earth (alpha_0). The weighted mean strength of the electromagnetic force over this redshift range in this location in the universe is da/a = (alpha_z - alpha_0)/alpha_0 = (-2.18 +/- 7.27) X 10^{-5}, i.e. we find no evidence for a temporal change from the 4 new very high redshift measurements. When the 4 new measurements are combined with a large existing sample of lower redshift measurements, a new limit on possible spatial variation of da/a is marginally preferred over a no-variation model at the 3.7 sigma level.

[27]  arXiv:2003.07639 [pdf, other]

Title: Do fragmentation and accretion affect the stellar Initial Mass Function?

Authors: R. Riaz, D.R.G. Schleicher, S. Vanaverbeke, Ralf S. Klessen

Comments: 12 Pages, 8 Figures, 1 Table; Accepted for publication in MNRAS

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

While the stellar Initial Mass Function (IMF) appears to be close to universal within the Milky Way galaxy, it is strongly suspected to be different in the primordial Universe, where molecular hydrogen cooling is less efficient and the gas temperature can be higher by a factor of 30. In between these extreme cases, the gas temperature varies depending on the environment, metallicity and radiation background. In this paper we explore if changes of the gas temperature affect the IMF of the stars considering fragmentation and accretion. The fragmentation behavior depends mostly on the Jeans mass at the turning point in the equation of state where a transition occurs from an approximately isothermal to an adiabatic regime due to dust opacities. The Jeans mass at this transition in the equation of state is always very similar, independent of the initial temperature, and therefore the initial mass of the fragments is very similar. Accretion on the other hand is strongly temperature dependent. We argue that the latter becomes the dominant process for star formation efficiencies above 5 - 7 %, increasing the average mass of the stars.

[28]  arXiv:2003.07641 [pdf, other]

Title: SimSpin -- Constructing mock IFS kinematic data cubes

Authors: K. E. Harborne, C. Power, A. S. G. Robotham

Comments: 14 pages, 10 figures. Accepted for publication in PASA

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

We present SimSpin, a new, public, software framework for generating integral field spectroscopy (IFS) data cubes from N-body/hydrodynamical simulations of galaxies, which can be compared directly with observational datasets. SimSpin provides a consistent method for studying a galaxy's stellar component. It can be used to explore how observationally inferred measurements of kinematics, such as the spin parameter $\lambda_R$, are impacted by the effects of, for example, inclination, seeing conditions, distance, etc. SimSpin is written in R and has been designed to be highly modular, flexible, and extensible. It is already being used by the astrophysics community to generate IFS-like cubes and FITS files for direct comparison of simulations to observations. In this paper, we explain the conceptual framework of SimSpin; how it is implemented in R; and we demonstrate SimSpin's current capabilities, providing as an example a brief investigation of how numerical resolution affects how reliably we can recover the intrinsic stellar kinematics of a simulated galaxy.

[29]  arXiv:2003.07644 [pdf, other]

Title: Probabilistic detection of spectral line components

Authors: Vlas Sokolov, Jaime E. Pineda, Johannes Buchner, Paola Caselli

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

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

Resolved kinematical information, such as from molecular gas in star forming regions, is obtained from spectral line observations. However, these observations often contain multiple line-of-sight components, making estimates harder to obtain and interpret. We present a fully automatic method that determines the number of components along the line of sight, or the spectral multiplicity, through Bayesian model selection. The underlying open-source framework, based on nested sampling and conventional spectral line modeling, is tested using the large area ammonia maps of NGC 1333 in Perseus molecular cloud obtained by the Green Bank Ammonia Survey (GAS). Compared to classic approaches, the presented method constrains velocities and velocity dispersions in a larger area. In addition, we find that the velocity dispersion distribution among multiple components did not change substantially from that of a single fit component analysis of the GAS data. These results showcase the power and relative ease of the fitting and model selection method, which makes it a unique tool to extract maximum information from complex spectral data.

[30]  arXiv:2003.07647 [pdf, other]

Title: Non-linear spherical collapse in tachyon models, and a comparison of collapse in tachyon and quintessence models of dark energy

Authors: Manvendra Pratap Rajvanshi, J. S. Bagla

Comments: 15 Pages, 11 Figures. Comments welcome

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

We study evolution of perturbations in dark matter and dark energy for spherical collapse. We study Tachyon models of dark energy using the approach outlined in Rajvanshi and Bagla (2018). We work with models that are allowed by current observations. We find that as with Quintessence models allowed by observations, dark energy perturbations do not affect evolution of perturbations in dark matter in a significant manner. Perturbations in dark energy remain small for such models. In order to compare different classes of dark energy models, we use reconstruction of potentials and study dark matter and dark energy perturbations for same expansion history in the two models. We find that dark matter perturbations carry no imprint of the class of dark energy models for the same expansion history: this is significant in that we can work with any convenient model to study clustering of dark matter. We find that the evolution of dark energy perturbations carries an imprint of the class of models in that these grow differently in Tachyon models and Quintessence models. However, the difference between these diminishes for (1+w)<<1 and hence prospects for differentiating between models using characteristics of perturbations are limited in our Universe.

[31]  arXiv:2003.07659 [pdf, other]

Title: Neutron Star Radius-to-mass Ratio from Partial Accretion Disc Occultation as Measured through Fe K$α$ Line Profiles

Authors: Riccardo La Placa, Luigi Stella, Alessando Papitto, Pavel Bakala, Tiziana Di Salvo, Maurizio Falanga, Vittorio De Falco, Alessandra De Rosa

Comments: 17 pages, 8 figures; this is a pre-print edition of an article that has been accepted for publication in the Astrophysical Journal

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

We present a new method to measure the radius-to-mass ratio (R/M) of weakly magnetic, disc-accreting neutron stars by exploiting the occultation of parts of the inner disc by the star itself. This occultation imprints characteristic features on the X-ray line profile that are unique and are expected to be present in low mass X-ray binary systems seen under inclinations higher than ~65 degrees. We analyse a NuSTAR observation of a good candidate system, 4U 1636-53, and find that X-ray spectra from current instrumentation are unlikely to single out the occultation features owing to insufficient signal-to-noise. Based on an extensive set of simulations we show that large-area X-ray detectors of the future generation could measure R/M to ~2{\div}3% precision over a range of inclinations. Such is the precision in radius determination required to derive tight constraints on the equation of state of ultradense matter and it represents the goal that other methods too aim to achieve in the future.

[32]  arXiv:2003.07660 [pdf, ps, other]

Title: Testing broad line region models with Reverberation Mapping

Authors: Hagai Netzer

Comments: 14 pages, 5 figures, 4 tables. Accepted for publication in MNRAS

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

New reverberation mapping (RM) measurements, combined with accurate luminosities and line ratios, provide strong constraints on the location of the line emitting gas in the broad line region (BLR) of active galactic nuclei (AGN). In this paper I present new calculations of radiation pressure and magnetic pressure confined clouds and apply them to a ``generic AGN'' and to NGC 5548. The new calculations are in good agreement with the observed lags of all broad emission lines, and with the luminosities of La, Civ 1549, Ovi 1035 and Heii 1640. They are also in reasonable agreement with the luminosities of Mgii 2798 and the 1990A blend of Ciii] and Siiii] lines for high metallicity gas. They explain the changes in time-lag following an increase in continuum luminosity and their dependencies on the inner and outer boundaries of the BLR. They also predict very strong Balmer and Paschen continua with important implications to continuum RM experiments. However, the calculated Balmer and Paschen line luminosities are too weak, by factors of 2-5. This ``Balmer line crisis'' was noted in several earlier works and is now confirmed and constrained by RM measurements that were not available in the past. It seems that present photoionization codes that use the escape probability formalism, fail to correctly compute the Balmer line luminosities in high density, large optical depth gas.

[33]  arXiv:2003.07663 [pdf, other]

Title: Time dependent modeling of electron acceleration and cooling during blazar flares

Authors: A. Dmytriiev, H. Sol, A. Zech

Comments: Proceeding of the 36th International Cosmic Ray Conference (ICRC2019), July 24th - August 1st, 2019, Madison, WI, U.S.A

Journal-ref: PoS(ICRC2019)662, Volume 358 - 36th International Cosmic Ray Conference (ICRC2019) - GRI - Gamma Ray Indirect

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

We present a new time-dependent leptonic code that we developed to model the varying multi-wavelength (MWL) emission during blazar flares. In our modeling, we assume that the blazar emission originates from a plasma blob located in the jet, and that relativistic electrons are injected into the blob and may undergo stochastic (Fermi II) or shock (Fermi I) acceleration. We numerically solve the kinetic equation for electron evolution in the blob, taking into account particle injection, escape, acceleration and radiative cooling. In order to calculate the spectral energy distribution (SED) of the blob emission we assume a synchrotron self-Compton (SSC) scenario, including also synchrotron self absorption and gamma-gamma absorption processes. Our code computes the evolution of the electron spectrum and of the associated broad-band SED. As a first application, we attempt to connect the continuous, steady-state emission from the blazar Mrk 421 with a flare observed in February 2010, using a minimal number of free parameters in a two-zone scenario in which a turbulent region is present around the emitting zone. Mrk 421 is a high-synchrotron-peaked (HSP) BL Lac, and one of the brightest extragalactic gamma-ray sources in the Very High Energy (VHE) gamma-ray band. It is also the closest TeV emitting blazar to the Earth (redshift z=0.031).

[34]  arXiv:2003.07676 [pdf, other]

Title: Limitations imposed by optical turbulence profile structure and evolution on tomographic reconstruction for the ELT

Authors: O. J. D. Farley, J. Osborn, T. Morris, T. Fusco, B. Neichel, C. Correia, R. W. Wilson

Comments: 13 pages, 13 figures. Accepted MNRAS March 2020

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

The performance of tomographic adaptive optics systems is intrinsically linked to the vertical profile of optical turbulence. Firstly, a sufficient number of discrete turbulent layers must be reconstructed to model the true continuous turbulence profile. Secondly over the course of an observation, the profile as seen by the telescope changes and the tomographic reconstructor must be updated. These changes can be due to the unpredictable evolution of turbulent layers on meteorological timescales as short as minutes. Here we investigate the effect of changing atmospheric conditions on the quality of tomographic reconstruction by coupling fast analytical adaptive optics simulation to a large database of 10 691 high resolution turbulence profiles measured over two years by the Stereo-SCIDAR instrument at ESO Paranal, Chile. This work represents the first investigation of these effects with a large, statistically significant sample of turbulence profiles. The statistical nature of the study allows us to assess not only the degradation and variability in tomographic error with a set of system parameters (e.g. number of layers, temporal update period) but also the required parameters to meet some error threshold. In the most challenging conditions where the profile is rapidly changing, these parameters must be far more tightly constrained in order to meet this threshold. By providing estimates of these constraints for a wide range of system geometries as well as the impact of different temporal optimisation strategies we may assist the designers of tomographic AO for the ELT to dimension their systems.

[35]  arXiv:2003.07707 [pdf, other]

Title: Mitigating flicker noise in high-precision photometry. I -- Characterization of the noise structure, impact on the inferred transit parameters, and predictions for CHEOPS observations

Authors: Sulis S., Lendl M., Hofmeister S., Veronig A., Fossati L., Cubillos P., Van Grootel V

Comments: 20 pages, 24 figures, accepted for publication in Astronomy & Astrophysics

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

In photometry, the short-timescale stellar variability ("flicker"), such as that caused by granulation and oscillations, can reach amplitudes comparable to the transit depth of Earth-sized planets and is correlated over the typical transit timescales. It can introduce systematic errors on the inferred planetary parameters when a small number of transits are observed. The objective of this paper is to characterize the statistical properties of this noise and quantify its impact on the inferred transit parameters. We used the extensive solar observations obtained with SoHO/VIRGO to characterize flicker noise. We simulated realistic transits across the solar disk using SDO/HMI data and used these to obtain transit light curves, which we used to estimate the errors made on the transit parameters. We make these light curves publicly available. To extend the study to a wider parameter range, we derived the properties of flicker noise using Kepler observations and studied their dependence on stellar parameters. Finally, we predicted the limiting stellar apparent magnitude for which the properties of the flicker noise can be extracted using high-precision CHEOPS and PLATO observations. Stellar granulation is a stochastic colored noise, and is stationary with respect to the stellar magnetic cycle. Both the flicker correlation timescales and amplitudes increase with the stellar mass and radius. If these correlations are not taken into account when fitting for the parameters of transiting exoplanets, this can bias the inferred parameters. In particular, we find errors of up to 10$\%$ on $R_p/R_s$ for an Earth-sized planet orbiting a Sun-like star. For F and G stars, flicker will significantly affect the inferred parameters of transits observed with CHEOPS and PLATO. Dedicated modeling strategies need to be developed to accurately characterize both the star and the transiting exoplanets.

[36]  arXiv:2003.07741 [pdf, other]

Title: Methodology and Performance of the Two-Year Galactic Plane Scanning Survey of Insight-HXMT

Authors: Na Sai, JinYuan Liao, ChengKui Li, Ju Guan, Chen Wang, Yi Nang, Yuan Liu, ChengCheng Guo, Shu Zhang, ShuangNan Zhang

Comments: 14 pages, 17 figures, accepted for publication in JHEAP

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

The Galactic plane scanning survey is one of the main scientific objectives of the Hard X-ray Modulation Telescope (known as Insight-HXMT). During the two-year operation of Insight-HXMT, more than 1000 scanning observations have been performed and the whole Galactic plane ($\rm 0^{\circ}<l<360^{\circ}$, $\rm -10^{\circ}<b<10^{\circ}$) has been covered completely. We summarize the Galactic plane scanning survey of Insight-HXMT for two years, including the characteristics of the scanning data, the data analysis process and the preliminary results of the Low-Energy telescope, the Medium-Energy telescope and the High-Energy telescope. With the light curve PSF fitting method, the fluxes of the known sources in the scanned area as well as the flux errors are obtained for each scanning observation. From the relationships of SNRs and fluxes, the $5\sigma$ sensitivities of three telescopes of Insight-HXMT are estimated as $\rm \sim7.6\times10^{-11}~erg cm^{-2}~s^{-1}$ ($\rm 3 mCrab,~1-6 keV$), $\rm \sim4.0\times10^{-10}~erg~cm^{-2}~s^{-1}$ ($\rm 20~mCrab,~7-40 keV$) and $\rm \sim2.6\times10^{-10}~erg cm^{-2}~s^{-1}$ ($\rm 18 mCrab,~25-100 keV$) for an individual scanning observation of $2-3$ hours, respectively. Up to September 2019, more than 800 X-ray sources with various types are monitored by the three telescopes and their long-term light curves with three energy bands are obtained to make further scientific analyses.

[37]  arXiv:2003.07765 [pdf, other]

Title: Kink Instabilities In Relativistic Jets Can Drive Quasi-Periodic Radiation Signatures

Authors: Lingyi Dong, Haocheng Zhang, Dimitrios Giannios

Comments: 10 pages, 9 figures, accepted for publication in MNRAS

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

Relativistic jets are highly collimated plasma outflows emerging from accreting black holes. They are launched with a significant amount of magnetic energy, which can be dissipated to accelerate nonthermal particles and give rise to electromagnetic radiation at larger scales. Kink instabilities can be an efficient mechanism to trigger dissipation of jet magnetic energy. While previous works have studied the conditions required for the growth of kink instabilities in relativistic jets, the radiation signatures of these instabilities have not been investigated in detail. In this paper, we aim to self-consistently study radiation and polarization signatures from kink instabilities in relativistic jets. We combine large-scale relativistic magnetohydrodynamic (RMHD) simulations with polarized radiation transfer of a magnetized jet, which emerges from the central engine and propagates through the surrounding medium. We observe that a localized region at the central spine of the jet exhibits the strongest kink instabilities, which we identify as the jet emission region. Very interestingly, we find quasi-periodic oscillation (QPO) signatures in the light curve from the emission region. Additionally, the polarization degree appears to be anti-correlated to flares in the light curves. Our analyses show that these QPO signatures are intrinsically driven by kink instabilities, where the period of the QPOs is associated to the kink growth time scale. The latter corresponds to weeks to months QPOs in blazars. The polarization signatures offer unique diagnostics for QPOs driven by kink instabilities.

[38]  arXiv:2003.07805 [pdf]

Title: A Flat-Panel Brightness Model for the Starlink Satellites and Measurement of their Absolute Visual Magnitude

Authors: Anthony Mallama

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

The Starlink satellites are shaped like flat panels. The flat sides face zenith and nadir during normal operations. Their brightness is determined by the product of the solar illumination on the downward facing side of the panel multiplied by the area of that side projected toward the observer on Earth. This geometry leads to a unique brightness function that is not shared by other satellites. For example, the observed brightness is very sensitive to the solar elevation angle. There are circumstances where sunlight only illuminates the upward facing side of the satellite rendering it invisible to Earth-based observers. A brightness model depending on the solar aspect and the observer aspect of the flat panel, in addition to the satellite distance, is described. Absolute brightness is the only free parameter of the model, and it is taken to be that at a distance of 1,000 km when the solar and observer factors are unity. This model has been successfully fitted to a set of observed magnitudes. The absolute visual magnitude of a Starlink satellite as determined from this fitting is 4.1 +/- 0.1. The model could be used to determine the absolute magnitude of the Starlink satellite known as Dark Sat which has a special low-albedo coating.

[39]  arXiv:2003.07822 [pdf, other]

Title: On the nature of the soft gamma-ray emission in the hard state of the black hole transient GRS 1716-249

Authors: T. Bassi, J. Malzac, M. Del Santo, E. Jourdain, J.-P. Roques, A. D'Aì, J.C.A. Miller-Jones, R. Belmont, S.E. Motta, A. Segreto, V. Testa, P. Casella

Comments: 14 pages, 8 figures. Accepted for publication in MNRAS

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

The black hole transient GRS 1716-249 was monitored from the radio to the gamma-ray band during its 2016-2017 outburst. This paper focuses on the Spectral Energy Distribution (SED) obtained in 2017 February-March, when GRS 1716-249 was in a bright hard spectral state. The soft gamma-ray data collected with the INTEGRAL/SPI telescope show the presence of a spectral component which is in excess of the thermal Comptonisation emission. This component is usually interpreted as inverse Compton emission from a tiny fraction of non-thermal electrons in the X-ray corona. We find that hybrid thermal/non-thermal Comptonisation models provide a good fit to the X/gamma-ray spectrum of GRS 1716-249. The best-fit parameters are typical of the bright hard state spectra observed in other black hole X-ray binaries. Moreover, the magnetised hybrid Comptonisation model BELM provides an upper limit on the intensity of the coronal magnetic field of about 1E+06 G. Alternatively, this soft gamma-ray emission could originate from synchrotron emission in the radio jet. In order to test this hypothesis, we fit the SED with the irradiated disc plus Comptonisation model combined with the jet internal shock emission model ISHEM. We found that a jet with an electron distribution of p~2.1 can reproduce the soft gamma-ray emission of GRS 1716-249. However, if we introduce the expected cooling break around 10 keV, the jet model can no longer explain the observed soft gamma-ray emission, unless the index of the electron energy distribution is significantly harder (p<2).

[40]  arXiv:2003.07830 [pdf, other]

Title: Discovery of GeV gamma-ray emission from M33 and Arp 299 with Fermi-LAT

Authors: Shao-Qiang Xi, Ruo-Yu Liu, Hai-Ming Zhang, Xiang-Yu Wang

Comments: 8 pages, 9 figures, 2 tables; Comments are welcome

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

Star-forming galaxies are huge reservoirs of cosmic rays (CRs) and these CRs convert a significant fraction of their energy into gamma-rays by colliding with the interstellar medium (ISM). Several nearby star-forming galaxies have been detected in GeV-TeV $\gamma$-rays. It is also found that the $\gamma$-ray luminosities in 0.1-100 GeV correlate well with indicators of star formation rates of the galaxies, such as the total infrared (IR) luminosity. In this paper, we report a systematic search for possible gamma-ray emission from galaxies in the IRAS Revised Bright Galaxies Sample, using 11.4 years of $\gamma$-ray data taken by the Fermi-LAT. Two new galaxies, M33 and Arp 299, are detected with significance of ${\rm TS}\geq 25$. The two galaxies are consistent with the empirical correlation between the $\gamma$-ray luminosity and total infrared luminosity, suggesting that their gamma-ray emissions should mainly originate from CRs interacting with ISM. Nevertheless, there is a tentative evidence that the flux of the gamma-ray emission from Arp 299 is variable. If the variability is true, part of the emission should originate from the obscured AGN in this interacting galaxy system. In addition, we find the gamma-ray excess in M33 locates at the northeast region of the galaxy, where a supergiant H II region, NGC 604, resides. This indicates that some bright star-forming regions in spiral galaxies could outshine the bulk of the galaxy disk in producing gamma-ray emission.

[41]  arXiv:2003.07835 [pdf, other]

Title: Nodal Precession in Closely Spaced Planet Pairs

Authors: Nora Bailey, Daniel Fabrycky

Comments: 18 pages, 11 figures, submitted to AJ

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

Planet-planet perturbations can cause planets' orbital elements to change on secular timescales. Previous work has evaluated the nodal precession rate for planets in the limit of low $\alpha$ (semi-major axis ratio, 0$<$$\alpha$$\leq$1). Our simulations show that systems at high $\alpha$ (or low period ratio), similar to multiplanet systems found in the Kepler survey, have a nodal precession rate that is more strongly dependent on eccentricity and inclination. We present a complete expansion of the nodal precession rate to fourth order in the disturbing function and show that this analytical solution much better describes the simulated N-body behavior of high-$\alpha$ planet pairs; at $\alpha\approx$ 0.5, the fourth-order solution on average reduces the median analytical error by a factor of 7.5 from linear theory and 6.2 from a second-order expansion. We set limits on eccentricity and inclination where the theory is precisely validated by N-body integrations, which can be useful in future secular treatments of planetary systems.

Cross-lists for Wed, 18 Mar 20

[42]  arXiv:2003.07363 (cross-list from hep-ph) [pdf, other]

Title: Axion Quark Nuggets. SkyQuakes and Other Mysterious Explosions

Authors: Dmitry Budker, Victor V. Flambaum, Ariel Zhitnitsky

Comments: 15 pages, 4 figures

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

We advocate an idea that some mysterious explosions, the so-called sky-quakes, which have been known for centuries could be a manifestation of the dark matter Axion Quark Nuggets (AQN) when they propagate in the Earth's atmosphere. We specifically study the event which occurred on July 31-st 2008 and was properly recorded by the dedicated Elginfield Infrasound Array (ELFO) near London, Ontario, Canada. The infrasound detection was accompanied by non-observation of any meteors by an all-sky camera network. Our interpretation is based on the AQN dark matter model which was originally invented with a completely different purpose---to explain the similarity of the dark and visible cosmological matter densities $\Omega_{\rm dark}\sim \Omega_{\rm visible}$. Our estimates for the infrasonic frequency $\nu\simeq 5$ Hz and overpressure $\delta p\sim 0.3$ Pa are consistent with the ELFO record. We propose a detection strategy for a systematic study to search for such explosions originating from AQNs by using Distributed Acoustic Sensing and briefly mention other possible detection methods. Specific signals from AQN tracks may also be detected by an existing network of seismic stations.

[43]  arXiv:2003.07375 (cross-list from gr-qc) [pdf, other]

Title: Generic searches for alternative gravitational wave polarizations with networks of interferometric detectors

Authors: Peter T. H. Pang, Rico K. L. Lo, Isaac C. F. Wong, Tjonnie G. F. Li, Chris Van Den Broeck

Comments: 7 pages, 3 figures

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

The detection of gravitational wave signals by Advanced LIGO and Advanced Virgo enables us to probe the polarization content of gravitational waves. In general relativity, only tensor modes are present, while in a variety of alternative theories one can also have vector or scalar modes. Recently test were performed which compared Bayesian evidences for the hypotheses that either purely tensor, purely vector, or purely scalar polarizations were present. Indeed, with only three detectors in a network and allowing for mixtures of tensor polarizations and alternative polarization states, it is not possible to identify precisely which non-standard polarizations might be in the signal and by what amounts. However, we demonstrate that one can still infer whether, in addition to tensor polarizations, alternative polarizations are present in the first place, irrespective of the detailed polarization content. We develop two methods to do this for sources with electromagnetic counterparts, both based on the so-called null stream. Apart from being able to detect mixtures of tensor and alternative polarizations, these have the added advantage that no waveform models are needed, and signals from any kind of transient source can be used. Both formalisms allow us to combine information from multiple sources so as to arrive at increasingly more stringent bounds. For now we apply these on the binary neutron star signal GW170817, showing consistency with the tensor-only hypothesis with p-values of 0.315 and 0.790 for the two methods.

[44]  arXiv:2003.07431 (cross-list from gr-qc) [pdf, ps, other]

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

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

Comments: 32 pages, 7 figures (18 eps files). Comments acknowledged

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

In this paper we investigate the asymptotic dynamics of inflationary cosmological models that are based in scalar-tensor theories of gravity. Our main aim is to explore the global structure of the phase space in the framework of single-field inflation models. For this purpose we make emphasis in the adequate choice of the variables of the phase space. Our results indicate that, although single-field inflation is generic in the sense that the corresponding critical point in the phase space exists for a wide class of potentials, along given phase space orbits -- representing potential cosmic histories -- the occurrence of the inflationary stage is rather dependent on the initial conditions. For the non-minimal coupling model with the $\phi^2$-potential, we have been able to give a rough estimate of the relative probability for initial conditions leading to slow-roll inflation: $10^{-13}\,\%\lesssim RP\ll 10^{-8}\,\%$. These bonds are greatly improved in the scalar-tensor models, including the Brans-Dicke theory, where the relative probability $RP\sim 50\,\%$. Hence slow-roll inflation is indeed a natural stage of the cosmic expansion in Brans-Dicke models of inflation. We also clarify an issue with the emergence of the $\Lambda$CDM cosmological model from the Brans-Dicke theory. It is confirmed as well that the dynamics of vacuum Brans-Dicke theories with arbitrary potentials are non-chaotic.

[45]  arXiv:2003.07519 (cross-list from gr-qc) [pdf, ps, other]

Title: Do black hole shadows merge?

Authors: Kazumasa Okabayashi, Nobuyuki Asaka, Ken-ichi Nakao

Comments: 9 pages, 4 figures

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

The so-called black hole shadow is not a silhouette of a black hole but an image of a collapsing object or a white hole. Hence it is non-trivial whether black hole shadows merge with each other when black holes coalesce with each other. In this paper, by analyzing the null geodesic generators of the event horizon in Kastor-Traschen spacetime which describes a coalescence of black boles, we see that observers who will never see a merger of black hole shadows exist.

[46]  arXiv:2003.07788 (cross-list from gr-qc) [pdf, ps, other]

Title: Black holes in the four-dimensional Einstein-Lovelock gravity

Authors: R. A. Konoplya, A. Zhidenko

Comments: 5 pages, 1 ancillary Mathematica(R) notebook

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

A $(3+1)$-dimensional Einstein-Gauss-Bonnet theory of gravity has been recently formulated in [D. Glavan and C. Lin, Phys. Rev. Lett. 124, 081301 (2020)] which is different from the pure Einstein theory, i.e. bypasses the Lovelock's theorem, and avoids Ostrogradsky instability. The theory was formulated in $D > 4$ dimensions and its action consists of the Einstein-Hilbert term with a cosmological constant, and the Gauss-Bonnet term multiplied by a factor $1/(D-4)$. Then, the four-dimensional theory is defined as the limit $D \to 4$. Here we generalize this approach to the four-dimensional Einstein-Lovelock theory and formulate the most general static $4D$ black-hole solution allowing for a $\Lambda$-term (either positive or negative) and electric charge $Q$. As the metric functions cannot be found in a closed form in the general case, we develop and share publicly the code which constructs the metric functions for every given set of parameters.

Replacements for Wed, 18 Mar 20

[47]  arXiv:1708.08149 (replaced) [pdf, ps, other]

Title: Molecular and Atomic Clouds toward the Wolf-Rayet Nebula NGC 2359: Possible Evidence for Isolated High-Mass Star Formation Triggered by a Cloud-Cloud Collision

Authors: Hidetoshi Sano, Katsuhiro Hayashi, Rei Enokiya, Kazufumi Torii, Shun Saeki, Kazuki Okawa, Kisetsu Tsuge, Daichi Tsutsumi, Mikito Kohno, Yusuke Hattori, Shinji Fujita, Satoshi Yoshiike, Ryuji Okamoto, Atsushi Nishimura, Akio Ohama, Takahiro Hayakawa, Hiroaki Yamamoto, Kengo Tachihara, Cristina Elisabet Cappa, Yasuo Fukui

Comments: 38 pages, 13 figures, 1 table, submitted to Publications of the Astronomical Society of Japan (PASJ)

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

[48]  arXiv:1808.05080 (replaced) [pdf, other]

Title: A Guide for CosmoMC Installation and Running

Authors: Hossein Moshafi, Majid Bahraminasr

Comments: 11 pages, 2 figures

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

[49]  arXiv:1904.09143 (replaced) [pdf, other]

Title: Search for ultralight scalar dark matter with NANOGrav pulsar timing arrays

Authors: Ryo Kato, Jiro Soda

Comments: 15 pages, 4 figures, 4 tables

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

[50]  arXiv:1905.08802 (replaced) [pdf, other]

Title: ALMA polarimetry measures magnetically aligned dust grains in the torus of NGC 1068

Authors: Enrique Lopez-Rodriguez, Almudena Alonso-Herrero, Santiago García-Burillo, Michael S. Gordon, Kohei Ichikawa, Masatoshi Imanishi, Seiji Kameno, Nancy A. Levenson, Robert Nikutta, Chris Packham

Comments: 19 pages, 11 figures (Accepted for Publication to ApJ)

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

[51]  arXiv:1907.01557 (replaced) [pdf, other]

Title: Neutron star mergers and rare core-collapse supernovae as sources of r-process enrichment in simulated galaxies

Authors: Freeke van de Voort (1, 2, 3), Rüdiger Pakmor (1), Robert J. J. Grand (1), Volker Springel (1), Facundo A. Gómez (4), Federico Marinacci (5) ((1) MPA (2) HITS (3) Yale (4) La Serena (5) Bologna)

Comments: Accepted for publication in MNRAS. Revised version: added Figure 13 (on mixing of iron and r-process elements) and an Appendix (on iron and magnesium abundances) and updated the r-process yields (Tables 1 and 2 and normalization of abundances)

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

[52]  arXiv:1907.06028 (replaced) [pdf, other]

Title: An extensive-air-shower-like event registered with the TUS orbital detector

Authors: B.A. Khrenov, G.K. Garipov, M.A. Kaznacheeva, P.A. Klimov, M.I. Panasyuk, V.L. Petrov, S.A. Sharakin, A.V. Shirokov, I.V. Yashin, M.Yu. Zotov, A.A. Grinyuk, V.M. Grebenyuk, M.V. Lavrova, L.G. Tkachev, A.V. Tkachenko, O.A. Saprykin, A.A. Botvinko, A.N. Senkovsky, A.E. Puchkov, M. Bertaina

Comments: 24 pages; v2: important changes to address comments by the anonymous referee; main conclusions unchanged

Journal-ref: JCAP 03 (2020) 033

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

[53]  arXiv:1907.07666 (replaced) [pdf, other]

Title: Helium and Nitrogen Enrichment in Massive Main Sequence Stars: Mechanisms and Implications for the Origin of WNL Stars

Authors: Arpita Roy, Ralph S Sutherland, Mark R Krumholz, Alexander Heger, Michael A Dopita

Comments: 21 pages, 18 figures, 2 tables, accepted for publication in MNRAS

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

[54]  arXiv:1909.04891 (replaced) [pdf, other]

Title: Uranus and Neptune: Origin, Evolution and Internal Structure

Authors: Ravit Helled, Nadine Nettelmann, Tristan Guillot

Comments: Accepted for publication in Space Science Reviews

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

[55]  arXiv:1910.14125 (replaced) [pdf, other]

Title: A new method to build the (inverse) distance ladder

Authors: David Camarena, Valerio Marra

Comments: 16 pages, 12 figures, 5 tables. v2 reflects version accepted for publication in MNRAS

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

[56]  arXiv:1911.04190 (replaced) [pdf, other]

Title: Comparing Short Gamma-Ray Burst Jet Structure Models

Authors: Fergus Hayes, Ik Siong Heng, John Veitch, Daniel Williams

Journal-ref: The Astrophysical Journal, 891(2), 124 (2020)

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

[57]  arXiv:1911.09596 (replaced) [pdf, other]

Title: Massive neutrinos and degeneracies in Lyman-alpha forest simulations

Authors: Christian Pedersen, Andreu Font-Ribera, Thomas D. Kitching, Patrick McDonald, Simeon Bird, Anže Slosar, Keir K. Rogers, Andrew Pontzen

Comments: 18 pages, 7 figures

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

[58]  arXiv:1911.11144 (replaced) [pdf, other]

Title: Probing the Small-Scale Matter Power Spectrum with Large-Scale 21-cm Data

Authors: Julian B. Muñoz, Cora Dvorkin, Francis-Yan Cyr-Racine

Comments: 23 pages, 16 figures. Matches accepted version

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

[59]  arXiv:1912.06369 (replaced) [pdf, ps, other]

Title: What constraints on the neutron star maximum mass can one pose from GW170817 observations?

Authors: Shunke Ai, He Gao, Bing Zhang

Comments: 12 pages, 4 figures, Accepted for publication on The Astrophysical Journal

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

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

Title: The PDFI_SS Electric Field Inversion Software

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

Comments: 67 pages, 28 figures, 3 tables

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

[61]  arXiv:2001.00838 (replaced) [pdf, other]

Title: Dynamical Simulations of the First Globular Clusters

Authors: Raymond G. Carlberg

Comments: ApJ accepted

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

[62]  arXiv:2002.00957 (replaced) [pdf, ps, other]

Title: The WISSH quasars project VII. The impact of extreme radiative field in the accretion disk and X-ray corona interplay

Authors: L. Zappacosta, E. Piconcelli, M. Giustini, G. Vietri, F. Duras, G. Miniutti, M. Bischetti, A. Bongiorno, M. Brusa, M. Chiaberge, A. Comastri, C. Feruglio, A. Luminari, A. Marconi, C. Ricci, C. Vignali, F. Fiore

Comments: 10 pages (including Appendix), 4 figures. Astronomy & Astrophysics Letters in press. Title numbering changed to match the published version

Journal-ref: A&A 635, L5 (2020)

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

[63]  arXiv:2002.05164 (replaced) [pdf, other]

Title: Inner Boundary Condition in Quasi-Lagrangian Simulations of Accretion Disks

Authors: Adam M. Dempsey, Diego Muñoz, Yoram Lithwick

Comments: 10 pages, 5 figures, Accepted to ApJL

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

[64]  arXiv:2003.06770 (replaced) [pdf, other]

Title: Intrinsic Color Indices of Early-Type Dwarf Stars

Authors: Dingshan Deng (1), Yang Sun (1), Mingjie Jian (2), Biwei Jiang (1), Haibo Yuan (1) ((1) Department of Astronomy, Beijing Normal University (2) Department of Astronomy, School of Science, The University of Tokyo)

Comments: 20 pages, 11 figures, accepted for publication in The Astronomical Journal

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

• New submissions
• Cross-lists
• Replacements