RAS_WEB (Page 2,752)

On the Magnetic Fields, Beaming Fractions, and Fastness Parameters of Pulsating Ultra-Luminous X-Ray Sources. (arXiv:2007.08102v1 [astro-ph.HE]) <a href="http://arxiv.org/find/astro-ph/1/au:+Erkut_M/0/1/0/all/0/1">M.H. Erkut</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Turkoglu_M/0/1/0/all/0/1">M.M. T&#xfc;rko&#x11f;lu</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Eksi_K/0/1/0/all/0/1">K.Y. Ek&#x15f;i</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Alpar_M/0/1/0/all/0/1">M.A. Alpar</a> Discovery of pulsating ultra-luminous X-ray sources (PULX) suggests that neutron stars are presumably common within the ultra-luminous X-ray source (ULX) population though the majority of the population members are currently lacking pulsations. These systems are likely to host neutron stars accreting mass at super-Eddington (super-critical) rates from their massive companion in high-mass X-ray binaries. Taking into account the spherization of the accretion flow in the super-critical regime, the beaming of X-ray emission, and the reduction of theRead More →

Magnetic Flux of Active Regions Determining the Eruptive Character of Large Solar Flares. (arXiv:2007.08127v1 [astro-ph.SR]) <a href="http://arxiv.org/find/astro-ph/1/au:+Li_T/0/1/0/all/0/1">Ting Li</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hou_Y/0/1/0/all/0/1">Yijun Hou</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Yang_S/0/1/0/all/0/1">Shuhong Yang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zhang_J/0/1/0/all/0/1">Jun Zhang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Liu_L/0/1/0/all/0/1">Lijuan Liu</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Veronig_A/0/1/0/all/0/1">Astrid M. Veronig</a> We establish the largest eruptive/confined flare database to date and analyze 322 flares of emph{GOES} class M1.0 and larger that occurred during 2010$-$2019, i.e., almost spanning the entire solar cycle 24. We find that the total unsigned magnetic flux ($Phi$$_{AR}$) of active regions (ARs) is a key parameter in governing the eruptive character of large flares, with the proportion of eruptive flares exhibiting a strong anti-correlation with $Phi$$_{AR}$. This means thatRead More →

Mass composition of cosmic rays determined by muon fraction with $varepsilon_{thr.} geq$ 1 GeV in air showers with energy greater than 5 EeV. (arXiv:2007.08135v1 [astro-ph.HE]) <a href="http://arxiv.org/find/astro-ph/1/au:+Knurenko_S/0/1/0/all/0/1">Stanislav Knurenko</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Petrov_I/0/1/0/all/0/1">Igor Petrov</a> The ratio of the number of muons with a threshold of 1 GeV and charged particles at a distance of 600 m from the axis is analyzed. Air showers with energies above 5 EeV and zenith angles with less than 60 degrees are considered. Comparison of experimental data with calculations by the QGSJETII-04 model for various primary nuclei, including a gamma ray, showed that the mass composition of cosmic rays up to energies ofRead More →

A polarization study of the supernova remnant CTB 80. (arXiv:2007.08138v1 [astro-ph.GA]) <a href="http://arxiv.org/find/astro-ph/1/au:+Li_X/0/1/0/all/0/1">Xianghua Li</a> (YNU), <a href="http://arxiv.org/find/astro-ph/1/au:+Sun_X/0/1/0/all/0/1">Xiaohui Sun</a> (YNU), <a href="http://arxiv.org/find/astro-ph/1/au:+Reich_W/0/1/0/all/0/1">Wolfgang Reich</a> (MPIfR), <a href="http://arxiv.org/find/astro-ph/1/au:+Gao_X/0/1/0/all/0/1">Xuyang Gao</a> (NAOC) We present a radio polarization study of the supernova remnant CTB 80 based on images at 1420 MHz from the Canadian Galactic plane survey, at 2695 MHz from the Effelsberg survey of the Galactic plane, and at 4800 MHz from the Sino-German 6cm polarization survey of the Galactic plane. We obtained a rotation measure (RM) map using polarization angles at 2695 MHz and 4800 MHz as the polarization percentages are similar at these two frequencies. RM exhibits aRead More →

Echoes of 2HDM inflation at the collider experiments. (arXiv:2007.08141v1 [hep-ph]) <a href="http://arxiv.org/find/hep-ph/1/au:+Modak_T/0/1/0/all/0/1">Tanmoy Modak</a>, <a href="http://arxiv.org/find/hep-ph/1/au:+Oda_K/0/1/0/all/0/1">Kin-ya Oda</a> We study the correlation between the constraints on general two Higgs doublet model from Higgs inflation and from collider experiments. The parameter space receives meaningful constraints from direct searches at the Large Hadron Collider and from flavor physics if $m_H$, $m_A$, and $m_{H^pm}$ are in the sub-TeV range, where $H$, $A$, and $H^pm$ are the CP even, CP odd, and charged Higgs bosons, respectively. We find that in the parameter region favored by the Higgs inflation, $H$, $A$, and $H^pm$ are nearly degenerate in mass.We show that such nearRead More →

Photoevaporation of Minihalos during Cosmic Reionization: Primordial and Metal-Enriched Halos. (arXiv:2007.08149v1 [astro-ph.GA]) <a href="http://arxiv.org/find/astro-ph/1/au:+Nakatani_R/0/1/0/all/0/1">Riouhei Nakatani</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Fialkov_A/0/1/0/all/0/1">Anastasia Fialkov</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Yoshida_N/0/1/0/all/0/1">Naoki Yoshida</a> The density distribution of the inter-galactic medium is an uncertain but highly important issue in the study of cosmic reionization. It is expected that there are abundant gas clouds hosted by low-mass “minihalos” in the early universe, which act as photon sinks until photoevaporated by the emerging ultra-violet background (UVB) radiation. We perform a suite of radiation hydrodynamics simulations to study the photoevaporation of minihalos. Our simulations follow hydrodynamics, non-equilibrium chemistry, and the associated cooling processes in a self-consistent manner. We conduct a parametricRead More →

Lyman-alpha radiative transfer: Modeling spectrum and surface brightness profile of Lyman-alpha emitting galaxies at z=3-6. (arXiv:2007.08172v1 [astro-ph.GA]) <a href="http://arxiv.org/find/astro-ph/1/au:+Song_H/0/1/0/all/0/1">Hyunmi Song</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Seon_K/0/1/0/all/0/1">Kwang-Il Seon</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hwang_H/0/1/0/all/0/1">Ho Seong Hwang</a> We perform Lyman-alpha radiative transfer calculations for reproducing Lyman-alpha properties of star-forming galaxies at high redshifts. We model a galaxy as a halo in which the density distributions of Lyman-alpha sources and H I plus dust medium are described with exponential functions. We also consider an outflow of the medium that represents a momentum-driven wind in a gravitational potential well. We successfully reproduce both the spectra and the surface brightness profiles of eight star-forming galaxies at z =3-6Read More →

Characterizing Astrophysical Binary Neutron Stars with Gravitational Waves. (arXiv:2007.08198v1 [astro-ph.HE]) <a href="http://arxiv.org/find/astro-ph/1/au:+Zhu_X/0/1/0/all/0/1">Xing-Jiang Zhu</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ashton_G/0/1/0/all/0/1">Gregory Ashton</a> Merging binary neutron stars are thought to be formed predominantly via isolated binary evolution. In this standard formation scenario, the first-born neutron star goes through a recycling process and might be rapidly spinning during the final inspiral, whereas the second-born star is expected to have effectively zero spin at merger. Based on this feature, we propose a new framework for the astrophysical characterization of binary neutron stars observed from their gravitational wave emission. We further propose a prior for the dimensionless spin magnitudes of recycled neutron stars, given byRead More →

Statistical model for filamentary structures of molecular clouds — The modified multiplicative random cascade model and its multifractal nature. (arXiv:2007.08206v1 [astro-ph.GA]) <a href="http://arxiv.org/find/astro-ph/1/au:+Robitaille_J/0/1/0/all/0/1">Jean-Fran&#xe7;ois Robitaille</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Abdeldayem_A/0/1/0/all/0/1">Abdelhalim Abdeldayem</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Joncour_I/0/1/0/all/0/1">Isabelle Joncour</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Moraux_E/0/1/0/all/0/1">Estelle Moraux</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Motte_F/0/1/0/all/0/1">Fr&#xe9;d&#xe9;rique Motte</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lesaffre_P/0/1/0/all/0/1">Pierre Lesaffre</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Khalil_A/0/1/0/all/0/1">Andr&#xe9; Khalil</a> We propose a new statistical model that can reproduce the hierarchical nature of the ubiquitous filamentary structures of molecular clouds. This model is based on the multiplicative random cascade, which is designed to replicate the multifractal nature of intermittency in developed turbulence. We present a modified version of the multiplicative process where the spatial fluctuations as a function of scales are produced withRead More →

A robust machine learning algorithm to search for continuous gravitational waves. (arXiv:2007.08207v1 [astro-ph.IM]) <a href="http://arxiv.org/find/astro-ph/1/au:+Bayley_J/0/1/0/all/0/1">Joseph Bayley</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Messenger_C/0/1/0/all/0/1">Chris Messenger</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Woan_G/0/1/0/all/0/1">Graham Woan</a> Many continuous gravitational wave searches are affected by instrumental spectral lines that could be confused with a continuous astrophysical signal. Several techniques have been developed to limit the effect of these lines by penalising signals that appear in only a single detector. We have developed a general method, using a convolutional neural network, to reduce the impact of instrumental artefacts on searches that use the SOAP algorithm. The method can identify features in corresponding frequency bands of each detector and classify these bandsRead More →

Dynamical signatures of Rossby vortices in cavity-hosting disks. (arXiv:2007.08215v1 [astro-ph.EP]) <a href="http://arxiv.org/find/astro-ph/1/au:+Robert_C/0/1/0/all/0/1">Cl&#xe9;ment Mathieu Tristan Robert</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Meheut_H/0/1/0/all/0/1">H&#xe9;lo&#xef;se M&#xe9;heut</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Menard_F/0/1/0/all/0/1">Fran&#xe7;ois M&#xe9;nard</a> Context: Planets are formed amidst young circumstellar disks of gas and dust. The latter is traced by thermal radiation, where strong asymmetric clumps were observed in a handful of cases. These dust traps could be key to understand the early stages of planet formation, when solids grow from micron-size to planetesimals. Aims: Vortices are among the few known asymmetric dust trapping scenarios. The present work aims at predicting their characteristics in a complementary observable. Namely, line-of-sight velocities are well suited to trace the presenceRead More →

24 synoptic maps of 296 prominence average magnetic fields measured by Hanle effect during cycle XXI ascending phase. (arXiv:2007.08219v1 [astro-ph.SR]) <a href="http://arxiv.org/find/astro-ph/1/au:+Bommier_V/0/1/0/all/0/1">V. Bommier</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Leroy_J/0/1/0/all/0/1">J.L. Leroy</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Sahal_Brechot_S/0/1/0/all/0/1">S. Sahal-Brechot</a> Aims : The aim of the present paper is to publish 24 synoptic maps of solar filaments, in which 296 prominence average unambiguous magnetic field vectors were determined by Pic-du-Midi observations between 1974 and 1982, which is the ascending phase of cycle XXI. Methods : The magnetic field was determined by interpretation of the Hanle effect observed in the He I D3 line. Previous results about the prominence field polarity and prominence chirality were applied toRead More →

Long, depolarising H$alpha$-filament towards the Monogem ring. (arXiv:2007.08221v1 [astro-ph.GA]) <a href="http://arxiv.org/find/astro-ph/1/au:+Reich_W/0/1/0/all/0/1">Wolfgang Reich</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Reich_P/0/1/0/all/0/1">Patricia Reich</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Sun_X/0/1/0/all/0/1">Xiaohui Sun</a> In soft X-rays, the Monogem ring is an object with a diameter of 25{deg} located in the Galactic anti-centre. It is believed to be a faint, evolved, local supernova remnant. The ring is also visible in the far-ultraviolet, and a few optical filaments are related. It is not seen at radio wavelengths, as other large supernova remnants are. We study a narrow about 4.5{deg} long, faint H$alpha$-filament, G203.7+11.5,that is seen towards the centre of the Monogem ring. It causes depolarisation and excessive Faraday rotation of radio polarisationRead More →

Master equation theory applied to the redistribution of polarized radiation in the weak radiation field limit. VI. Application to the Second Solar Spectrum of the Na I D1 & D2 lines: convergence. (arXiv:2007.08226v1 [astro-ph.SR]) <a href="http://arxiv.org/find/astro-ph/1/au:+Bommier_V/0/1/0/all/0/1">V. Bommier</a> This paper presents a numerical application of a self-consistent theory of partial redistribution in non-LTE conditions, developed in previous papers of the series. The code was described in a previous paper of this series. However, in that previous paper (number IV of the series), the numerical results were unrealistic. The present paper presents an approximation, which was able to restore the reliability of the outgoing polarization profiles. TheRead More →

The quest for a plausible formation route of formyl cyanide in the interstellar medium: a state-of-the-art quantum-chemical and kinetic approach. (arXiv:2007.08232v1 [astro-ph.GA]) <a href="http://arxiv.org/find/astro-ph/1/au:+Tonolo_F/0/1/0/all/0/1">F. Tonolo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lupi_J/0/1/0/all/0/1">J. Lupi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Puzzarini_C/0/1/0/all/0/1">C. Puzzarini</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Barone_V/0/1/0/all/0/1">V. Barone</a> Interstellar complex organic molecules (iCOMs) are assumed to be mainly formed on dust-grain surfaces. However, neutral gas-phase reactions in the interstellar medium (ISM) can play an important role. In this paper, by investigating the reaction between aldehydes and the cyano radical, we show that both formaldehyde (CH$_2$O) and acetaldehyde (CH$_3$CHO) can lead to the formation of formyl cyanide (HCOCN). Owing to accurate quantum-chemical computations followed by rate constant evaluations, we haveRead More →

Migrating Low-Mass Planets in Inviscid Dusty Protoplanetary Discs. (arXiv:2007.08235v1 [astro-ph.EP]) <a href="http://arxiv.org/find/astro-ph/1/au:+Hsieh_H/0/1/0/all/0/1">He-Feng Hsieh</a> (NTHU, ASIAA), <a href="http://arxiv.org/find/astro-ph/1/au:+Lin_M/0/1/0/all/0/1">Min-Kai Lin</a> (ASIAA) Disc-driven planet migration is integral to the formation of planetary systems. In standard, gas-dominated protoplanetary discs, low-mass planets or planetary cores undergo rapid inwards migration and are lost to the central star. However, several recent studies indicate that the solid component in protoplanetary discs can have a significant dynamical effect on disc-planet interaction, especially when the solid-to-gas mass ratio approaches unity or larger and the dust-on-gas drag forces become significant. As there are several ways to raise the solid abundance in protoplanetary discs, for example throughRead More →

Statistical description of dust polarized emission from the diffuse interstellar medium — A WST/RWST approach. (arXiv:2007.08242v1 [astro-ph.CO]) <a href="http://arxiv.org/find/astro-ph/1/au:+Blancard_B/0/1/0/all/0/1">Bruno Regaldo-Saint Blancard</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Levrier_F/0/1/0/all/0/1">Fran&#xe7;ois Levrier</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Allys_E/0/1/0/all/0/1">Erwan Allys</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bellomi_E/0/1/0/all/0/1">Elena Bellomi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Boulanger_F/0/1/0/all/0/1">Fran&#xe7;ois Boulanger</a> The statistical characterization of the diffuse magnetized ISM and Galactic foregrounds to the CMB poses a major challenge. To account for their non-Gaussian statistics, we need a data analysis approach capable of efficiently quantifying statistical couplings across scales. This information is encoded in the data, but most of it is lost when using conventional tools as one-point statistics and power spectra. The Wavelet Scattering Transform (WST), a low-variance statistical descriptor of non-GaussianRead More →

Hydrodynamic Winds From Twin-Star Binaries. (arXiv:2007.07252v1 [astro-ph.SR]) <a href="http://arxiv.org/find/astro-ph/1/au:+MacLeod_M/0/1/0/all/0/1">Morgan MacLeod</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Loeb_A/0/1/0/all/0/1">Abraham Loeb</a> Stellar winds shape the evolution of stars through the loss of mass. In binary systems, they also shape the stars’ evolution by modifying the orbit. In this paper, we use hydrodynamic simulations to study the emergence of nearly-isothermal winds from identical-twin binaries. We vary the degree to which model stars fill their Roche lobes and the temperature of the wind. Initialized at rest on the stellar surfaces, winds accelerate away from the binary components through a sonic surface to supersonic outward velocities. In cases where the binary fills its Roche lobe, aRead More →

The impact of signal-to-noise, redshift, and angular range on the bias of weak lensing 2-point functions. (arXiv:2007.07253v1 [astro-ph.CO]) <a href="http://arxiv.org/find/astro-ph/1/au:+Louca_A/0/1/0/all/0/1">Amy J. Louca</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Sellentin_E/0/1/0/all/0/1">Elena Sellentin</a> Weak lensing data follow a naturally skewed distribution, implying the data vector most likely yielded from a survey will systematically fall below its mean. Although this effect is qualitatively known from CMB-analyses, correctly accounting for it in weak lensing is challenging, as a direct transfer of the CMB results is quantitatively incorrect. While a previous study (Sellentin et al. 2018) focused on the magnitude of this bias, we here focus on the frequency of this bias, its scaling with redshift,Read More →

3D dynamics of the Orion cloud complex — Discovery of coherent radial gas motions at the 100-pc scale. (arXiv:2007.07254v1 [astro-ph.SR]) <a href="http://arxiv.org/find/astro-ph/1/au:+Grossschedl_J/0/1/0/all/0/1">Josefa E. Gro&#xdf;schedl</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Alves_J/0/1/0/all/0/1">Jo&#xe3;o Alves</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Meingast_S/0/1/0/all/0/1">Stefan Meingast</a> We present the first study of the 3D dynamics of the gas in the entire Southern Orion cloud complex. We used the YSO’s proper motions from Gaia as a proxy for the gas proper motion, together with gas radial velocities from archival CO data, to compute the space motion of the different star-forming clouds in the complex, including sub-regions in Orion A, Orion B, and two outlying cometary clouds. From the analysis of the cloud’sRead More →