RAS_WEB (Page 4,635)

Dust trapping in protoplanetary disks. (arXiv:1902.00005v1 [astro-ph.EP]) <a href="http://arxiv.org/find/astro-ph/1/au:+Marel_N/0/1/0/all/0/1">Nienke van der Marel</a> (NRC Herzberg, Victoria, BC, Canada) Planet formation is thought to begin with the growth of dust particles in protoplanetary disks from micrometer to millimeter and centimeter sizes. Dust growth is hindered by a number of growth barriers, according to dust evolution theory, while observational evidence indicates that somehow these barriers must have been overcome. The observational evidence of dust traps, in particular the Oph IRS 48 disk, with the Atacama Large Millimeter/submillimeter Array (ALMA) has changed our view of the dust growth process. In this article I review the history of dust trappingRead More →

In Search of the Thermal Eccentricity Distribution. (arXiv:1902.00019v1 [astro-ph.SR]) <a href="http://arxiv.org/find/astro-ph/1/au:+Geller_A/0/1/0/all/0/1">Aaron M. Geller</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Leigh_N/0/1/0/all/0/1">Nathan W. C. Leigh</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Giersz_M/0/1/0/all/0/1">Mirek Giersz</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kremer_K/0/1/0/all/0/1">Kyle Kremer</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Rasio_F/0/1/0/all/0/1">Frederic A. Rasio</a> About a century ago, Jeans (1919) discovered that if binary stars reach a state approximating energy equipartition, for example through many dynamical encounters that exchange energy, their eccentricity distribution can be described by : dN/de = 2e. This is referred to as the thermal eccentricity distribution, and has been widely used for initial conditions in theoretical investigations of binary stars. However, observations suggest that the eccentricity distributions of most observed binaries, and particularly those with masses <Read More →

Multiband gravitational-wave event rates and stellar physics. (arXiv:1902.00021v1 [astro-ph.HE]) <a href="http://arxiv.org/find/astro-ph/1/au:+Gerosa_D/0/1/0/all/0/1">Davide Gerosa</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ma_S/0/1/0/all/0/1">Sizheng Ma</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wong_K/0/1/0/all/0/1">Kaze W.K. Wong</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Berti_E/0/1/0/all/0/1">Emanuele Berti</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+OShaughnessy_R/0/1/0/all/0/1">Richard O&#x27;Shaughnessy</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Chen_Y/0/1/0/all/0/1">Yanbei Chen</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Belczynski_K/0/1/0/all/0/1">Krzysztof Belczynski</a> Joint gravitational-wave detections of stellar-mass black-hole binaries by ground- and space-based observatories will provide unprecedented opportunities for fundamental physics and astronomy. We present a semi-analytic method to estimate multiband event rates by combining selection effects of ground-based interferometers (like LIGO/Virgo) and space missions (like LISA). We forecast the expected number of multiband detections first by using information from current LIGO/Virgo data, and then through population synthesis simulations of binary stars. We estimate that fewRead More →

Constraining Gas Motions in the Intra-Cluster Medium. (arXiv:1902.00024v1 [astro-ph.CO]) <a href="http://arxiv.org/find/astro-ph/1/au:+Simionescu_A/0/1/0/all/0/1">A. Simionescu</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+ZuHone_J/0/1/0/all/0/1">J. ZuHone</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zhuravleva_I/0/1/0/all/0/1">I. Zhuravleva</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Churazov_E/0/1/0/all/0/1">E. Churazov</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gaspari_M/0/1/0/all/0/1">M. Gaspari</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Nagai_D/0/1/0/all/0/1">D. Nagai</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Werner_N/0/1/0/all/0/1">N. Werner</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Roediger_E/0/1/0/all/0/1">E. Roediger</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Canning_R/0/1/0/all/0/1">R. E. A. Canning</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Eckert_D/0/1/0/all/0/1">D. Eckert</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gu_L/0/1/0/all/0/1">L. Gu</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Paerels_F/0/1/0/all/0/1">F. Paerels</a> The detailed velocity structure of the diffuse X-ray emitting intra-cluster medium (ICM) remains one of the last missing key ingredients in understanding the microphysical properties of these hot baryons and constraining our models of the growth and evolution of structure on the largest scales in the Universe. Direct measurements of the gas velocities from the widths and shiftsRead More →

Towards Machine-assisted Meta-Studies: The Hubble Constant. (arXiv:1902.00027v1 [astro-ph.IM]) <a href="http://arxiv.org/find/astro-ph/1/au:+Crossland_T/0/1/0/all/0/1">Tom Crossland</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Stenetorp_P/0/1/0/all/0/1">Pontus Stenetorp</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Riedel_S/0/1/0/all/0/1">Sebastian Riedel</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kawata_D/0/1/0/all/0/1">Daisuke Kawata</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kitching_T/0/1/0/all/0/1">Thomas D. Kitching</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Croft_R/0/1/0/all/0/1">Rupert A. C. Croft</a> We present an approach for automatic extraction of measured values from the astrophysical literature, using the Hubble constant for our pilot study. Our rules-based model — a classical technique in natural language processing — has successfully extracted 298 measurements of the Hubble constant, with uncertainties, from the 208,541 available arXiv astrophysics papers. We have also created an artificial neural network classifier to identify papers which report novel measurements. This classifier is applied to the available arXivRead More →

Supernovae feedback propagation: the role of turbulence. (arXiv:1902.00028v1 [astro-ph.GA]) <a href="http://arxiv.org/find/astro-ph/1/au:+Ohlin_L/0/1/0/all/0/1">Loke Ohlin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Renaud_F/0/1/0/all/0/1">Florent Renaud</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Agertz_O/0/1/0/all/0/1">Oscar Agertz</a> Modelling the propagation of supernova (SN) bubbles, in terms of energy, momentum and spatial extent, is critical for simulations of galaxy evolution which do not capture these scales. To date, small scale models of SN feedback predict that the evolution of above-mentioned quantities can be solely parameterised by average quantities of the surrounding gas, such as density. However, most of these studies neglect the turbulent motions of this medium. In this paper, we study the propagation and evolution of SNe in turbulent environments. We confirm that theRead More →

The Three Causes of Low-Mass Assembly Bias. (arXiv:1902.00030v1 [astro-ph.CO]) <a href="http://arxiv.org/find/astro-ph/1/au:+Mansfield_P/0/1/0/all/0/1">Philip Mansfield</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kravtsov_A/0/1/0/all/0/1">Andrey V. Kravtsov</a> We present a detailed analysis of the physical processes that cause halo assembly bias — the dependence of halo clustering on proxies of halo formation time. We focus on the origin of assembly bias in the mass range corresponding to the hosts of typical galaxies and use halo concentration as our chief proxy of halo formation time. We also repeat our key analyses across a broad range of halo masses and for alternative formation time definitions. We show that splashback subhaloes are responsible for two thirds of the assemblyRead More →

Scattered light shadows in warped protoplanetary discs. (arXiv:1902.00036v1 [astro-ph.EP]) <a href="http://arxiv.org/find/astro-ph/1/au:+Nealon_R/0/1/0/all/0/1">Rebecca Nealon</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Pinte_C/0/1/0/all/0/1">Christophe Pinte</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Alexander_R/0/1/0/all/0/1">Richard Alexander</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mentiplay_D/0/1/0/all/0/1">Daniel Mentiplay</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Dipierro_G/0/1/0/all/0/1">Giovanni Dipierro</a> Three-dimensional hydrodynamic numerical simulations have demonstrated that the structure of a protoplanetary disc may be strongly affected by a planet orbiting in a plane that is misaligned to the disc. When the planet is able to open a gap, the disc is separated into an inner, precessing disc and an outer disc with a warp. In this work, we compute infrared scattered light images to investigate the observational consequences of such an arrangement. We find that an inner disc misaligned byRead More →

Signatures of Bimodality in Nebular Phase Type Ia Supernova Spectra: Indications of White Dwarf Collision Progenitors. (arXiv:1902.00037v1 [astro-ph.HE]) <a href="http://arxiv.org/find/astro-ph/1/au:+Vallely_P/0/1/0/all/0/1">P. J. Vallely</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tucker_M/0/1/0/all/0/1">M. A. Tucker</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Shappee_B/0/1/0/all/0/1">B. J. Shappee</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Brown_J/0/1/0/all/0/1">J. S. Brown</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Stanek_K/0/1/0/all/0/1">K. Z. Stanek</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kochanek_C/0/1/0/all/0/1">C. S. Kochanek</a> One observational prediction for Type Ia supernova (SNe Ia) explosions produced through white dwarf-white dwarf collisions is the presence of bimodal velocity distributions for the $^{56}$Ni decay products. These bimodal velocity distributions can manifest as double-peaked or flat-topped spectral features in late-time spectroscopic observations for favorable viewing angles. We present nebular phase spectroscopic observations of 17 SNe Ia obtained with the Large BinocularRead More →

Euclid Preparation IV. Impact of undetected galaxies on weak lensing shear measurements. (arXiv:1902.00044v1 [astro-ph.CO]) <a href="http://arxiv.org/find/astro-ph/1/au:+Collaboration_Euclid/0/1/0/all/0/1">Euclid Collaboration</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Martinet_N/0/1/0/all/0/1">N. Martinet</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Schrabback_T/0/1/0/all/0/1">T. Schrabback</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hoekstra_H/0/1/0/all/0/1">H. Hoekstra</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tewes_M/0/1/0/all/0/1">M. Tewes</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Herbonnet_R/0/1/0/all/0/1">R. Herbonnet</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Schneider_P/0/1/0/all/0/1">P. Schneider</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hernandez_Martin_B/0/1/0/all/0/1">B. Hernandez-Martin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Taylor_A/0/1/0/all/0/1">A.N. Taylor</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Brinchmann_J/0/1/0/all/0/1">J. Brinchmann</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Carvalho_C/0/1/0/all/0/1">C.S. Carvalho</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Castellano_M/0/1/0/all/0/1">M. Castellano</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Congedo_G/0/1/0/all/0/1">G. Congedo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gillis_B/0/1/0/all/0/1">B.R. Gillis</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Jullo_E/0/1/0/all/0/1">E. Jullo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kummel_M/0/1/0/all/0/1">M. K&#xfc;mmel</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ligori_S/0/1/0/all/0/1">S. Ligori</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lilje_P/0/1/0/all/0/1">P.B. Lilje</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Padilla_C/0/1/0/all/0/1">C. Padilla</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Paris_D/0/1/0/all/0/1">D. Paris</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Peacock_J/0/1/0/all/0/1">J.A. Peacock</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Pilo_S/0/1/0/all/0/1">S. Pilo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Pujol_A/0/1/0/all/0/1">A. Pujol</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Scott_D/0/1/0/all/0/1">D. Scott</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Toledo_Moreo_R/0/1/0/all/0/1">R. Toledo-Moreo</a> In modern weak lensing surveys, shape measurement algorithms are calibrated using simulations in order to correctRead More →

Topography of (exo)planets. (arXiv:1902.00047v1 [astro-ph.EP]) <a href="http://arxiv.org/find/astro-ph/1/au:+Landais_F/0/1/0/all/0/1">Fran&#xe7;ois Landais</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Schmidt_F/0/1/0/all/0/1">Frederic Schmidt</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lovejoy_S/0/1/0/all/0/1">Shaun Lovejoy</a> Current technology is not able to map the topography of rocky exoplanets, simply because the objects are too faint and far away to resolve them. Nevertheless, indirect effect of topography should be soon observable thanks to photometry techniques, and the possibility of detecting specular reflections. In addition, topography may have a strong effect on Earth-like exoplanet climates because oceans and mountains affect the distribution of clouds citep{Houze2012}. Also topography is critical for evaluating surface habitability citep{Dohm2015}. We propose here a general statistical theory to describe and generate realistic synthetic topographies ofRead More →

Inaccuracy of Spatial Derivatives in Simulations of Supersonic Turbulence. (arXiv:1902.00079v1 [physics.flu-dyn]) <a href="http://arxiv.org/find/physics/1/au:+Pan_L/0/1/0/all/0/1">Liubin Pan</a>, <a href="http://arxiv.org/find/physics/1/au:+Padoan_P/0/1/0/all/0/1">Paolo Padoan</a>, <a href="http://arxiv.org/find/physics/1/au:+Nordlund_%7B/0/1/0/all/0/1">&#xc5;ke Nordlund</a> We examine the accuracy of spatial derivatives computed from numerical simulations of supersonic turbulence. Two sets of simulations, carried out using a finite-volume code that evolves the hydrodynamic equations with an approximate Riemann solver and a finite-difference code that solves the Navier-Stokes equations, are tested against a number of criteria based on the continuity equation, including exact results at statistically steady state. We find that the spatial derivatives in the Navier-Stokes runs are accurate and satisfy all the criteria. In particular, they satisfy our exactRead More →

Star Cluster Catalogs for the LEGUS Dwarf Galaxies. (arXiv:1902.00082v1 [astro-ph.GA]) <a href="http://arxiv.org/find/astro-ph/1/au:+Cook_D/0/1/0/all/0/1">D.O. Cook</a> (1 and 2), <a href="http://arxiv.org/find/astro-ph/1/au:+Lee_J/0/1/0/all/0/1">J.C. Lee</a> (2), <a href="http://arxiv.org/find/astro-ph/1/au:+Adamo_A/0/1/0/all/0/1">A. Adamo</a> (3), <a href="http://arxiv.org/find/astro-ph/1/au:+Kim_H/0/1/0/all/0/1">H. Kim</a> (4), <a href="http://arxiv.org/find/astro-ph/1/au:+Chandar_R/0/1/0/all/0/1">R. Chandar</a> (5), <a href="http://arxiv.org/find/astro-ph/1/au:+Whitmore_B/0/1/0/all/0/1">B.C. Whitmore</a> (6), <a href="http://arxiv.org/find/astro-ph/1/au:+Mok_A/0/1/0/all/0/1">A. Mok</a> (5), <a href="http://arxiv.org/find/astro-ph/1/au:+Ryon_J/0/1/0/all/0/1">J.E. Ryon</a> (6), <a href="http://arxiv.org/find/astro-ph/1/au:+Dale_D/0/1/0/all/0/1">D.A. Dale</a> (7), <a href="http://arxiv.org/find/astro-ph/1/au:+Calzetti_D/0/1/0/all/0/1">D. Calzetti</a> (8), <a href="http://arxiv.org/find/astro-ph/1/au:+Andrews_J/0/1/0/all/0/1">J.E. Andrews</a> (9), <a href="http://arxiv.org/find/astro-ph/1/au:+Aloisi_A/0/1/0/all/0/1">A. Aloisi</a> (6), <a href="http://arxiv.org/find/astro-ph/1/au:+Ashworth_G/0/1/0/all/0/1">G. Ashworth</a> (10), <a href="http://arxiv.org/find/astro-ph/1/au:+Bright_S/0/1/0/all/0/1">S.N. Bright</a> (6), <a href="http://arxiv.org/find/astro-ph/1/au:+Brown_T/0/1/0/all/0/1">T.M. Brown</a> (6), <a href="http://arxiv.org/find/astro-ph/1/au:+Christian_C/0/1/0/all/0/1">C. Christian</a> (6), <a href="http://arxiv.org/find/astro-ph/1/au:+Cignoni_M/0/1/0/all/0/1">M. Cignoni</a> (11), <a href="http://arxiv.org/find/astro-ph/1/au:+Clayton_G/0/1/0/all/0/1">G.C. Clayton</a> (12), <a href="http://arxiv.org/find/astro-ph/1/au:+Silva_R/0/1/0/all/0/1">R. da Silva</a> (13), <a href="http://arxiv.org/find/astro-ph/1/au:+Mink_S/0/1/0/all/0/1">S.E. de Mink</a> (14), <a href="http://arxiv.org/find/astro-ph/1/au:+Dobbs_C/0/1/0/all/0/1">C.L. Dobbs</a> (15), <a href="http://arxiv.org/find/astro-ph/1/au:+Elmegreen_B/0/1/0/all/0/1">B.G. Elmegreen</a> (16), <a href="http://arxiv.org/find/astro-ph/1/au:+Elmegreen_D/0/1/0/all/0/1">D.M. Elmegreen</a>Read More →

Cloud Atlas: High-Contrast Time-Resolved Observations of Planetary-Mass Companions. (arXiv:1902.00085v1 [astro-ph.EP]) <a href="http://arxiv.org/find/astro-ph/1/au:+Zhou_Y/0/1/0/all/0/1">Yifan Zhou</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Apai_D/0/1/0/all/0/1">D&#xe1;niel Apai</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lew_B/0/1/0/all/0/1">Ben W. P. Lew</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Schneider_G/0/1/0/all/0/1">Glenn Schneider</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Manjavacas_E/0/1/0/all/0/1">Elena Manjavacas</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bedin_L/0/1/0/all/0/1">Luigi R. Bedin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Cowan_N/0/1/0/all/0/1">Nicolas B. Cowan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Marley_M/0/1/0/all/0/1">Mark S. Marley</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Radigan_J/0/1/0/all/0/1">Jacqueline Radigan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+karalidi_T/0/1/0/all/0/1">Theodora karalidi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lowrance_P/0/1/0/all/0/1">Patrick J. Lowrance</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Miels_Paez_P/0/1/0/all/0/1">Paulo A. Miels-P&#xe1;ez</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Metchev_S/0/1/0/all/0/1">Stanimir Metchev</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Burgasser_A/0/1/0/all/0/1">Adam J. Burgasser</a> Directly-imaged planetary-mass companions offer unique opportunities in atmospheric studies of exoplanets. They share characteristics of both brown dwarfs and transiting exoplanets, therefore, are critical for connecting atmospheric characterizations for these objects. Rotational phase mapping is a powerful technique to constrain the condensate cloud properties inRead More →

Modelling of Mg II lines in solar prominences. (arXiv:1902.00086v1 [astro-ph.SR]) <a href="http://arxiv.org/find/astro-ph/1/au:+Levens_P/0/1/0/all/0/1">Peter James Levens</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Labrosse_N/0/1/0/all/0/1">Nicolas Labrosse</a> Observations of the Mg II h and k lines in solar prominences with IRIS reveal a wide range of line shapes from simple non-reversed profiles to typical double-peaked reversed profiles with many other complex line shapes possible. The physical conditions responsible for this variety are not well understood. Our aim is to understand how physical conditions inside a prominence slab influence shapes and properties of emergent Mg II line profiles. We compute the spectrum of Mg II lines using a one-dimensional non-LTE radiative transfer code for two largeRead More →

Production and detection of an axion dark matter echo. (arXiv:1902.00114v1 [hep-ph]) <a href="http://arxiv.org/find/hep-ph/1/au:+Arza_A/0/1/0/all/0/1">Ariel Arza</a>, <a href="http://arxiv.org/find/hep-ph/1/au:+Sikivie_P/0/1/0/all/0/1">Pierre Sikivie</a> Electromagnetic radiation with angular frequency equal to half the axion mass stimulates the decay of cold dark matter axions and produces an echo, i.e. faint electromagnetic radiation traveling in the opposite direction. We propose to search for axion dark matter by sending out to space a powerful beam of microwave radiation and listening for its echo. We find that this is a promising approach to axion detection in the $2 times 10^{-7}$ to $3 times 10^{-4}$ eV mass range. Electromagnetic radiation with angular frequency equal to half theRead More →