RAS_WEB (Page 4,568)

Inefficient volatile loss from the Moon-forming disk: reconciling the giant impact hypothesis and a wet Moon. (arXiv:1812.10502v1 [astro-ph.EP]) <a href="http://arxiv.org/find/astro-ph/1/au:+Nakajima_M/0/1/0/all/0/1">Miki Nakajima</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Stevenson_D/0/1/0/all/0/1">David J. Stevenson</a> The Earth’s Moon is thought to have formed from a circumterrestrial disk generated by a giant impact between the proto-Earth and an impactor approximately 4.5 billion years ago. Since the impact was energetic, the disk would have been hot and partially vaporized. This formation process is thought to be responsible for the geochemical observation that the Moon is depleted in volatiles. This model predicts that the Moon should be significantly depleted in water as well, but this appears to contradictRead More →

Marvel analysis of the measured high-resolution rovibrational spectra of H2S. (arXiv:1812.10503v1 [astro-ph.EP]) <a href="http://arxiv.org/find/astro-ph/1/au:+Chubb_K/0/1/0/all/0/1">Katy L. Chubb</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Naumenko_O/0/1/0/all/0/1">Olga Naumenko</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Keely_S/0/1/0/all/0/1">Stefan Keely</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bartolotto_S/0/1/0/all/0/1">Sebestiano Bartolotto</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Macdonald_S/0/1/0/all/0/1">Skye Macdonald</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mukhtar_M/0/1/0/all/0/1">Mahmoud Mukhtar</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Grachov_A/0/1/0/all/0/1">Andrey Grachov</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+White_J/0/1/0/all/0/1">Joe White</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Coleman_E/0/1/0/all/0/1">Eden Coleman</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Liu_A/0/1/0/all/0/1">Anwen Liu</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Fazliev_A/0/1/0/all/0/1">Alexander Z. Fazliev</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Polovtseva_E/0/1/0/all/0/1">Elena R. Polovtseva</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Horneman_V/0/1/0/all/0/1">Veli-Matti Horneman</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Campargue_A/0/1/0/all/0/1">Alain Campargue</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Furtenbacher_T/0/1/0/all/0/1">Tibor Furtenbacher</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Csaszar_A/0/1/0/all/0/1">Attila G. Cs&#xe1;sz&#xe1;r</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Yurchenko_S/0/1/0/all/0/1">Sergei N. Yurchenko</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tennyson_J/0/1/0/all/0/1">Jonathan Tennyson</a> 44325 measured and assigned transitions of H$_2^{32}$S, the parent isotopologue of the hydrogen sulfide molecule, are collated from 33 publications into a single database and reviewed critically. Based on this information, rotation-vibration energy levelsRead More →

Machine Learning on Difference Image Analysis: A comparison of methods for transient detection. (arXiv:1812.10518v1 [astro-ph.IM]) <a href="http://arxiv.org/find/astro-ph/1/au:+Sanchez_B/0/1/0/all/0/1">B. S&#xe1;nchez</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+R%2E_M/0/1/0/all/0/1">M. J. Dom&#xed;nguez R.</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lares_M/0/1/0/all/0/1">M. Lares</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Beroiz_M/0/1/0/all/0/1">M. Beroiz</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Cabral_J/0/1/0/all/0/1">J. B. Cabral</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gurovich_S/0/1/0/all/0/1">S. Gurovich</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Quinones_C/0/1/0/all/0/1">C. Qui&#xf1;ones</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Artola_R/0/1/0/all/0/1">R. Artola</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Colazo_C/0/1/0/all/0/1">C. Colazo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Schneiter_M/0/1/0/all/0/1">M. Schneiter</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Girardini_C/0/1/0/all/0/1">C. Girardini</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tornatore_M/0/1/0/all/0/1">M. Tornatore</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Castellon_J/0/1/0/all/0/1">J. L. Nilo Castell&#xf3;n</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lambas_D/0/1/0/all/0/1">D. Garc&#xed;a Lambas</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Diaz_M/0/1/0/all/0/1">M. C. D&#xed;az</a> We present a comparison of several Difference Image Analysis (DIA) techniques, in combination with Machine Learning (ML) algorithms, applied to the identification of optical transients associated with gravitational wave events. Each technique is assessed based on the scoringRead More →

Non-thermal Dark Matter from Modified Early Matter Domination. (arXiv:1812.10522v1 [hep-ph]) <a href="http://arxiv.org/find/hep-ph/1/au:+Allahverdi_R/0/1/0/all/0/1">Rouzbeh Allahverdi</a>, <a href="http://arxiv.org/find/hep-ph/1/au:+Osinski_J/0/1/0/all/0/1">Jacek K. Osi&#x144;ski</a> Thermal freeze-out or freeze-in during a period of early matter domination can give rise to the correct dark matter abundance for $langle sigma_{rm ann} v rangle_{rm f} < 3 times 10^{-26}$ cm$^3$ s$^{-1}$. In the standard scenario, a single field that behaves like matter drives the early matter dominated era. However, in realistic models, this epoch may involve more than one field. In this paper, we study the effect of such a modification on the production of dark matter during early matter domination. We show that even aRead More →

Probing Cosmic Acceleration by Using Model-Independent Parametrizations and Three Kinds of Supernova Statistics Techniques. (arXiv:1812.10542v1 [astro-ph.CO]) <a href="http://arxiv.org/find/astro-ph/1/au:+Luo_X/0/1/0/all/0/1">Xiaolin Luo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wang_S/0/1/0/all/0/1">Shuang Wang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wen_S/0/1/0/all/0/1">Sixiang Wen</a> In this work, we explore the evolution of the dark energy equation of state {omega} by using Chevalliear-PolarskiLinder (CPL) parametrization and the binned parametrizations. For binned parametrizations, we adopt three methods to choose the redshift interval: I. Ensure that “{Delta}z = const”, where {Delta}z is the width of each bin; II.Ensure that “n{Delta}z = const”, where n is the number of SNIa in each bin; III. Treat redshift discontinuity points as models parameters, i.e. “free {Delta}z”. For observational data, weRead More →

Time evolution of rotating and magnetized white dwarf stars. (arXiv:1812.10543v1 [astro-ph.SR]) <a href="http://arxiv.org/find/astro-ph/1/au:+Becerra_L/0/1/0/all/0/1">Laura Becerra</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Boshkayev_K/0/1/0/all/0/1">Kuantay Boshkayev</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Rueda_J/0/1/0/all/0/1">Jorge. A. Rueda</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ruffini_R/0/1/0/all/0/1">Remo Ruffini</a> We investigate the evolution of isolated, zero and finite temperature, massive, uniformly rotating and highly magnetized white dwarf stars under angular momentum loss driven by magnetic dipole braking. We consider the structure and thermal evolution of the white dwarf isothermal core taking also into account the nuclear burning and neutrino emission processes. We estimate the white dwarf lifetime before it reaches the condition either for a type Ia supernova explosion or for the gravitational collapse to a neutron star. We analyzeRead More →

Overstable Convective Modes of Rotating Hot Jupiters. (arXiv:1812.10598v1 [astro-ph.EP]) <a href="http://arxiv.org/find/astro-ph/1/au:+Lee_U/0/1/0/all/0/1">Umin Lee</a> We calculate overstable convective modes of uniformly rotating hot Jupiters, which have a convective core and a thin radiative envelope. Convective modes in rotating planets have complex frequency $omega$ and are stabilized by rapid rotation so that their growth rates $proptoomega_{rm I}={rm Im}(omega)$ are much smaller than those for the non-rotating planets. The stabilized convective modes excite low frequency gravity waves in the radiative envelope by frequency resonance between them. We find that the convective modes that excite envelope gravity waves remain unstable even in the presence of non-adiabatic dissipations in the envelope.Read More →

Melanopogenesis: Dark Matter of (almost) any Mass and Baryonic Matter from the Evaporation of Primordial Black Holes weighing a Ton (or less). (arXiv:1812.10606v1 [astro-ph.CO]) <a href="http://arxiv.org/find/astro-ph/1/au:+Morrison_L/0/1/0/all/0/1">Logan Morrison</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Profumo_S/0/1/0/all/0/1">Stefano Profumo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Yu_Y/0/1/0/all/0/1">Yan Yu</a> The evaporation of primordial black holes with a mass in the $1 {rm gram}lesssim M_{rm PBH}lesssim$1000 kg range can lead to the production of dark matter particles of almost any mass in the range $0.1 {rm MeV}lesssim m_{rm DM}lesssim 10^{18}$ GeV with the right relic density at very early times, $taulesssim 10^{-10}$ s. We calculate, as a function of the primordial black holes mass and initial abundance, the combination of dark matterRead More →

Intra-Night Optical Variability Monitoring of Fermi Blazars: First Results from 1.3 m J C Bhattacharya Telescope. (arXiv:1812.10614v1 [astro-ph.HE]) <a href="http://arxiv.org/find/astro-ph/1/au:+Paliya_V/0/1/0/all/0/1">Vaidehi S. Paliya</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Stalin_C/0/1/0/all/0/1">C. S. Stalin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ajello_M/0/1/0/all/0/1">M. Ajello</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kaur_A/0/1/0/all/0/1">A. Kaur</a> We report the first results obtained from our campaign to characterize the intranight-optical variability (INOV) properties of {it Fermi}~detected blazars, using the observations from the recently commissioned 1.3 m J C Bhattacharya telescope (JCBT). During the first run, we were able to observe 17 blazars in the Bessel $R$ filter for $sim$137 hrs. Using $C$ and scaled $F$-statistics, we quantify the extent of INOV and derive the duty cycle (DC) which is theRead More →

Secondary eclipses of WASP-18b — Near Infrared observations with the Anglo Australian Telescope, the Magellan Clay Telescope and the LCOGT network. (arXiv:1812.10623v1 [astro-ph.EP]) <a href="http://arxiv.org/find/astro-ph/1/au:+Kedziora_Chudczer_L/0/1/0/all/0/1">L. Kedziora-Chudczer</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zhou_G/0/1/0/all/0/1">G. Zhou</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bailey_J/0/1/0/all/0/1">J. Bailey</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bayliss_D/0/1/0/all/0/1">D.D.R. Bayliss</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tinney_C/0/1/0/all/0/1">C.G. Tinney</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Osip_D/0/1/0/all/0/1">D. Osip</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Colon_K/0/1/0/all/0/1">K.D. Colon</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Shporer_A/0/1/0/all/0/1">A. Shporer</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Dragomir_D/0/1/0/all/0/1">D. Dragomir</a> We present new eclipse observations for one of the hottest “hot Jupiters” WASP-18b, for which previously published data from HST WFC3 and Spitzer have led to radically conflicting conclusions about the composition of this planet’s atmosphere. We measure eclipse depths of $0.15pm0.02%$ at $Ks$ and $0.07pm0.01%$ at $z’$ bands. Using the VSTAR line-by-line radiative transferRead More →

Influence of Ohmic and ambipolar heating on thermal structure of accretion discs. (arXiv:1812.10634v1 [astro-ph.SR]) <a href="http://arxiv.org/find/astro-ph/1/au:+Khaibrakhmanov_S/0/1/0/all/0/1">Sergey A. Khaibrakhmanov</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Dudorov_A/0/1/0/all/0/1">Alexander E. Dudorov</a> We investigate dynamics of accretion discs of young stars with fossil large-scale magnetic field. Our magneto-gas-dynamic (MHD) model of the accretion discs includes equations of Shakura and Sunyaev, induction equation, equations of thermal and collisional ionization. Induction equation takes into account Ohmic and magnetic ambipolar diffusion, magnetic buoyancy. We also consider the influence of Ohmic and ambipolar heating on thermal structure of the accretion discs. We analyse the influence of considered dissipative MHD effects on the temperature of the accretion discs around classicalRead More →

CMB lensing bi-spectrum: assessing analytical predictions against full-sky lensing simulations. (arXiv:1812.10635v1 [astro-ph.CO]) <a href="http://arxiv.org/find/astro-ph/1/au:+Namikawa_T/0/1/0/all/0/1">Toshiya Namikawa</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bose_B/0/1/0/all/0/1">Benjamin Bose</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bouchet_F/0/1/0/all/0/1">Fran&#xe7;ois R. Bouchet</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Takahashi_R/0/1/0/all/0/1">Ryuichi Takahashi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Taruya_A/0/1/0/all/0/1">Atsushi Taruya</a> Cosmic microwave background (CMB) lensing is an integrated effect whose kernel is greater than half the peak value in the range $1Read More →

Radial trends in Galactic globular clusters and their possible origin. (arXiv:1812.10656v1 [astro-ph.GA]) <a href="http://arxiv.org/find/astro-ph/1/au:+Kravtsov_V/0/1/0/all/0/1">Valery V. Kravtsov</a> (1 and 2) ((1) SAI, Lomonosov Moscow State University, Moscow, Russia, (2) INCT, Universidad de Atacama, Copiapo, Chile) The relaxation time at the half-mass radius of Galactic globular clusters (GGCs) is typically within a few Gyr. Hence, the majority of GGCs are expected to be well relaxed systems, given their age is around 12-13 Gyr. So any initial radial segregation between stars of the same initial mass on the main sequence (MS), in particular, the progenitors of the present day sub-giant and red-giant branch (SGB, RGB) stars should alreadyRead More →

A uniform search for thermonuclear burst oscillations in the RXTE legacy dataset. (arXiv:1812.10684v1 [astro-ph.HE]) <a href="http://arxiv.org/find/astro-ph/1/au:+Bilous_A/0/1/0/all/0/1">Anna V. Bilous</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Watts_A/0/1/0/all/0/1">Anna L. Watts</a> We describe a blind uniform search for thermonuclear burst oscillations (TBOs) in the majority of Type-I bursts observed by RXTE (2118 bursts from 57 neutron stars). We examined 2-2002 Hz power spectra from the Fourier transform in sliding 0.5-2 s windows, using fine-binned light curves in 2-60 keV energy range. The significance of the oscillation candidates was assessed by simulations which took into account light curve variations, dead time and sliding time windows. Some of our sources exhibited multi-frequency variability below approximately 15Read More →

Two kinematically distinct old globular cluster populations in the Large Magellanic Cloud. (arXiv:1812.10709v1 [astro-ph.GA]) <a href="http://arxiv.org/find/astro-ph/1/au:+Piatti_A/0/1/0/all/0/1">Andr&#xe9;s E. Piatti</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Alfaro_E/0/1/0/all/0/1">Emilio J. Alfaro</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Cantat_Gaudin_T/0/1/0/all/0/1">Tristan Cantat-Gaudin</a> We report results of proper motions of 15 known Large Magellanic Cloud (LMC) old globular clusters (GCs) derived from the Gaia DR2 data sets. When these mean proper motions are gathered with existent radial velocity measurements to compose the GCs’ velocity vectors, we found that the projection of the velocity vectors onto the LMC plane and those perpendicular to it tell us about two distinct kinematic GC populations. Such a distinction becomes clear if the GCs are split at aRead More →

On the absence of dark matter in dwarf galaxies surrounding the Milky Way. (arXiv:1812.10714v1 [astro-ph.GA]) <a href="http://arxiv.org/find/astro-ph/1/au:+Hammer_F/0/1/0/all/0/1">Francois Hammer</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Yang_Y/0/1/0/all/0/1">Yanbin Yang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wang_J/0/1/0/all/0/1">Jianling Wang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Arenou_F/0/1/0/all/0/1">Frederic Arenou</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Puech_M/0/1/0/all/0/1">Mathieu Puech</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Flores_H/0/1/0/all/0/1">Hector Flores</a> It is widely accepted that Milky Way (MW) dwarfs are the most dark matter (DM) dominated galaxies. Their DM content is estimated through its projected density along the line of sight (los). Here we demonstrate that this quantity correlates with their distance to the MW, falsifying the calculations of DM in dwarfs. Moreover, we show that the acceleration deduced from the los velocity dispersion is entirely due to MW tidal shocks. ThisRead More →

Detection of Fast Radio Bursts on the Large Scanning Antenna of the Lebedev Physical Institute. (arXiv:1812.10716v1 [astro-ph.IM]) <a href="http://arxiv.org/find/astro-ph/1/au:+Fedorova_V/0/1/0/all/0/1">Viktoriya Fedorova</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Rodin_A/0/1/0/all/0/1">Alexander Rodin</a> Results of a search for individual impulsive signals on the Large Scanning Antenna of the Lebedev Physical Institute at 111 MHz carried out from July 2012 through May 2018 are presented. The data were convolved with a template of a specified form and convolved with a test dispersion measure. A region of sky with central coordinates $alpha = 05^h 32^m;$ $delta = +41.72^circ$ and also a region of sky around the coordinates fixed earlier for FRB 121102 ($alpha = 05^h 32^m;$ $deltaRead More →

On times and shadows: the observational analemma. (arXiv:1812.10719v1 [physics.ed-ph]) <a href="http://arxiv.org/find/physics/1/au:+Gangui_A/0/1/0/all/0/1">Alejandro Gangui</a>, <a href="http://arxiv.org/find/physics/1/au:+Lastra_C/0/1/0/all/0/1">Cecilia Lastra</a>, <a href="http://arxiv.org/find/physics/1/au:+Karaseur_F/0/1/0/all/0/1">Fernando Karaseur</a> The observation that the shadows of objects change during the course of the day and also for a fixed time during a year led curious minds to realize that the Sun could be used as a timekeeper. However, the daily motion of the Sun has some subtleties, for example, with regards to the precise time at which it crosses the meridian near noon. When the Sun is on the meridian, a clock is used to ascertain this time and a vertical stick determines the angle the SunRead More →

Indication of Another Intermediate-mass Black Hole in the Galactic Center. (arXiv:1812.10733v1 [astro-ph.GA]) <a href="http://arxiv.org/find/astro-ph/1/au:+Takekawa_S/0/1/0/all/0/1">Shunya Takekawa</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Oka_T/0/1/0/all/0/1">Tomoharu Oka</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Iwata_Y/0/1/0/all/0/1">Yuhei Iwata</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tsujimoto_S/0/1/0/all/0/1">Shiho Tsujimoto</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Nomura_M/0/1/0/all/0/1">Mariko Nomura</a> We report the discovery of molecular gas streams orbiting around an invisible massive object in the central region of our Galaxy, based on the high-resolution molecular line observations with the Atacama Large Millimeter/submillimeter Array (ALMA). The morphology and kinematics of these streams can be reproduced well through two Keplerian orbits around a single point mass of $(3.2 pm 0.6)times 10^4 M_odot$. We also found ionized gas toward the inner part of the orbiting gas, indicating dissociative shock and/orRead More →

Ultra High Energy Cosmic Rays: Origin, Composition and Spectrum. (arXiv:1812.10750v1 [astro-ph.HE]) <a href="http://arxiv.org/find/astro-ph/1/au:+Aloisio_R/0/1/0/all/0/1">Roberto Aloisio</a> The physics of Ultra High Energy Cosmic Rays will be reviewed, discussing the latest experimental results and theoretical models aiming at explaining the observations in terms of spectra, mass composition and possible sources. It will be also discussed the emission of secondary particles such as neutrinos and gamma rays produced by the interaction of Ultra High Energy Cosmic Rays with astrophysical photon backgrounds. The physics of Ultra High Energy Cosmic Rays will be reviewed, discussing the latest experimental results and theoretical models aiming at explaining the observations in terms of spectra,Read More →