RAS_WEB (Page 22)

Modelling the Track of the GD-1 Stellar Stream Inside a Host with a Fermionic Dark Matter Core-Halo Distribution Mart’in F. Mestre, Carlos R. Arg"uelles, Daniel D. Carpintero, Valentina Crespi, Andreas Krut arXiv:2404.19102v1 Announce Type: new Abstract: Traditional studies on stellar streams typically involve phenomenological $Lambda$CDM halos or ad hoc dark matter (DM) profiles with different degrees of triaxiality, which preclude to gain insights into the nature and mass of the DM particles. Recently, a Maximum Entropy Principle of halo formation has been applied to provide a DM halo model which incorporates the fermionic (quantum) nature of the particles, while leading to DM profiles which dependRead More →

Tayler Instability Revisited Valentin A. Skoutnev, Andrei M. Beloborodov arXiv:2404.19103v1 Announce Type: new Abstract: Tayler instability of toroidal magnetic fields $B_phi$ is broadly invoked as a trigger for turbulence and angular momentum transport in stars. This paper presents a systematic revision of the linear stability analysis for a rotating, magnetized, and stably stratified star. For plausible configurations of $B_phi$, instability requires diffusive processes: viscosity, magnetic diffusivity, or thermal/compositional diffusion. Our results reveal a new physical picture, demonstrating how different diffusive effects independently trigger instability of two types of waves in the rotating star: magnetostrophic waves and inertial waves. It develops via overstability of the waves,Read More →

The calm before the (next) storm: no third outburst in 2019–2020, and ongoing monitoring of the transient AGN IC 3599 Dirk Grupe (Northern Kentucky University), S. Komossa (Max-Planck-Institut fuer Radio-Astronomie), Salem Wolsing (Northern Kentucky University) arXiv:2404.19107v1 Announce Type: new Abstract: We report on follow-up observations of the Seyfert 1.9 galaxy IC 3599 with the NASA Neil Gehrels Swift mission. The detection of a second X-ray outburst in 2010 by Swift after the first discovery of a bright X-ray outburst in 1990 by ROSAT led to the suggestion of two very different explanations: The first one assumed that IC 3599 exhibits outbursts due to repeated partialRead More →

A Panchromatic Study of the X-ray Binary Population in NGC 300 on Sub-Galactic Scales Breanna A. Binder, Rosalie Williams, Jacob Payne, Michael Eracleous, Alexander Belles, Benjamin F. Williams arXiv:2404.19129v1 Announce Type: new Abstract: The population-wide properties and demographics of extragalactic X-ray binaries (XRBs) correlate with the star formation rates (SFRs), stellar masses ($M_{star}$), and environmental factors (such as metallicity, $Z$) of their host galaxy. Although there is evidence that XRB scaling relations ($L_X$/SFR for high mass XRBs [HMXBs] and $L_X$/$M_{star}$ for low mass XRBs [LMXBs]) may depend on metallicity and stellar age across large samples of XRB-hosting galaxies, disentangling the effects of metallicity and stellarRead More →

Capillary processes in extraterrestrial contexts Daniel Cordier, Gerard Liger-Belair, David A. Bonhommeau, Thomas Seon, Thomas Appere, Nathalie Carrasco arXiv:2404.19131v1 Announce Type: new Abstract: The Earth is no longer the only known celestial body containing one or more liquid phases. The Cassini spacecraft has discovered seas of hydrocarbons at the surface of Titan, while a series of corroborating evidences argue in favour of the existence of an aqueous ocean beneath the icy crust of several moons. Capillarity embraces a family of physical processes occurring at the free surface of a liquid. These phenomena depend on the liquid properties and on the local planetary conditions. Capillarity mayRead More →

Long term CCD photometry of the distant cluster NGC 2419: the CMD revisited A. Arellano Ferro, S. Muneer, Sunetra Giridhar, I. Bustos Fierro, M. A. Yepez, G. A. Garc’ia P’erez, G. Rios Segura arXiv:2404.19151v1 Announce Type: new Abstract: Employing emph{VI} images of NGC 2419 acquired over 17 years, light curves for most of the known variables in the field of the cluster are produced. A cluster membership analysis for about 3100 stars in the cluster field with proper motions from $Gaia$-DR3, revealed the presence of member stars as far as 140 pc from the cluster center and enabled the construction of a cleaner CMD freeRead More →

On the Determining Physical Factor of Jet-Related Coronal Mass Ejection’s Morphology in the High Corona Yadan Duan, Yuandeng Shen, Zehao Tang, Chenrui Zhou, Song Tan arXiv:2404.19179v1 Announce Type: new Abstract: A solar jet can often cause coronal mass ejections (CMEs) with different morphologies in the high corona, for example, jet-like CMEs, bubble-like CMEs, and so-called twin CMEs that include a pair of simultaneous jet-like and bubble-like CMEs. However, what determines the morphology of a jet-related CME is still an open question. Using high spatiotemporal resolution stereoscopic observations taken by the Solar Dynamics Observatory (SDO) and the Solar Terrestrial Relations Observatory (STEREO) from October 2010 toRead More →

Low-energy Injection and Nonthermal Particle Acceleration in Relativistic Magnetic Turbulence Divjyot Singh, Omar French, Fan Guo, Xiaocan Li arXiv:2404.19181v1 Announce Type: new Abstract: Relativistic magnetic turbulence has been proposed as a process for producing nonthermal particles in high-energy astrophysics. The particle energization may be contributed by both magnetic reconnection and turbulent fluctuations, but their interplay is poorly understood. It has been suggested that during magnetic reconnection the parallel electric field dominates the particle acceleration up to the lower bound of the power-law particle spectrum, but recent studies show that electric fields perpendicular to the magnetic field can play an important, if not dominant role. InRead More →

Updated observational constraints on spatially-flat and non-flat $Lambda$CDM and XCDM cosmological models Javier de Cruz Perez, Chan-Gyung Park, Bharat Ratra arXiv:2404.19194v1 Announce Type: new Abstract: We study 6 LCDM models, with 4 allowing for non-flat geometry and 3 allowing for a non-unity lensing consistency parameter $A_L$. We also study 6 XCDM models with a dynamical dark energy density X-fluid with equation of state $w$. For the non-flat models we use two different primordial power spectra, Planck $P(q)$ and new $P(q)$. These models are tested against: Planck 2018 CMB power spectra (P18) and lensing potential power spectrum (lensing), and an updated compilation of BAO, SNIa, $H(z)$,Read More →

Optical Spectroscopy of Type Ia Supernovae by the Carnegie Supernova Projects I and II N. Morrell (Carnegie Observatories, Las Campanas Observatory, La Serena, Chile), M. M. Phillips (Carnegie Observatories, Las Campanas Observatory, La Serena, Chile), G. Folatelli (Instituto de Astrof’isica de La Plata), M. D. Stritzinger (Department of Physics and Astronomy, Aarhus University, Aarhus, Denmark), M. Hamuy (Fundaci’on Chilena de Astronom’ia, Santiago, Chile), N. B. Suntzeff (George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Texas A&M University, Department of Physics and Astronomy, College Station, Texas, USA), E. Y. Hsiao (Department of Physics, Florida State University, Tallahassee, Florida, USA), F. Taddia (DepartmentRead More →

Chandra Study of the Proper Motion of HST-1 in the Jet of M87 Rameshan Thimmappa, Joseph Neilsen, Daryl Haggard, Michael A. Nowak, Sera Markoff arXiv:2404.19272v1 Announce Type: new Abstract: The radio galaxy M87 is well known for its jet, which features a series of bright knots observable from radio to X-ray wavelengths. We analyze the X-ray image and flux variability of the knot HST-1 in the jet. Our analysis includes all 112 available textit{Chandra} ACIS-S observations from 2000-2021, with a total exposure time of $sim$887 ks. We use de-convolved images to study the brightness profile of the X-ray jet and measure the relative separation betweenRead More →

Study of bound and resonant states of NS molecule in the R-matrix approach F. Iacob, T. Meltzer, J. Zs. Mezei, I. F. Schneider, J. Tennyson arXiv:2404.19298v1 Announce Type: new Abstract: The bound and resonance states along with corresponding autoionization widths for nitrogen sulphide (NS) molecule are determined using electron NS$^+$ cation scattering calculations. The calculations are performed for $^2{Sigma}^+$, $^2{Pi}$ and $^2Delta$ total symmetries using the ab initio R-matrix method for both bound and continuum states. Calculations are performed on a grid of 106 points for internuclear separations between 1.32 and 3 $AA$. The resonance states yield dissociative potential curves which, when considered together withRead More →

Phase-Dependent Spectral Shape Changes in the Ultraluminous X-Ray Pulsar NGC 5907 ULX1 Daiki Miura (Department of Physics, Graduate School of Science, The University of Tokyo, Institute of Space and Astronautical Science), Shogo B. Kobayashi (Department of Physics, Tokyo University of Science), Hiroya Yamaguchi (Institute of Space and Astronautical Science, Department of Physics, Graduate School of Science, The University of Tokyo) arXiv:2404.19300v1 Announce Type: new Abstract: Discovery of coherent pulsations from several ultraluminous X-ray pulsars (ULXPs) has provided direct evidence of super-critical accretion flow. However, geometrical structure of such accretion flow onto the central neutron star remains poorly understood. NGC 5907 ULX1 is one of theRead More →

Dissociative recombination of the CH$^+$ molecular ion at low energy K. Chakrabarti, J. Zs Mezei, O. Motapon, A. Faure, O. Dulieu, K. Hassouni, I. F. Schneider arXiv:2404.19302v1 Announce Type: new Abstract: The reactive collisions of the CH$^+$ molecular ion with electrons is studied in the framework of the multichannel quantum defect theory, taking into account the contribution of the core-excited Rydberg states. In addition to the $X^1Sigma^+$ ground state of the ion, we also consider the contribution to the dynamics of the $a^3Pi$ and $A^1Pi$ excited states of CH$^+$. Our results – in the case of the dissociative recombination in good agreement with the storageRead More →

Neutrinos in Cosmology Eleonora Di Valentino, Stefano Gariazzo, Olga Mena arXiv:2404.19322v1 Announce Type: new Abstract: Neutrinos are the least known particle in the Standard Model of elementary particle physics. They play a crucial role in cosmology, governing the universe’s evolution and shaping the large-scale structures we observe today. In this chapter, we review crucial topics in neutrino cosmology, such as the neutrino decoupling process in the very early universe. We shall also revisit the current constraints on the number of effective relativistic degrees of freedom and the departures from its standard expectation of 3. Neutrino masses represent the very first departure from the Standard ModelRead More →

Energy dependence of Quasi-periodic oscillations in accreting X-ray pulsars Hemanth Manikantan, Biswajit Paul, Rahul Sharma, Pragati Pradhan, Vikram Rana arXiv:2404.19323v1 Announce Type: new Abstract: We present the results from an investigation of the energy dependence of Quasi-Periodic Oscillations (QPOs) exhibited by accreting X-ray pulsars using data from archival textit{XMM-Newton}, textit{NuSTAR}, textit{RXTE}, and textit{NICER} observations. In a search for the presence of QPOs in 99 textit{XMM-Newton} and textit{NuSTAR} observations, we detected QPOs in eleven observations of five sources, viz., 4U 1626–67 (48 mHz), IGR J19294+1816 (30 mHz), V 0332+53 (2, 18 and 40 mHz), Cen X–3 (30 mHz), and XTE J1858+034 (180 mHz). A positive correlationRead More →

Revisiting the Constraint on Equation of State of Neutron Star based on the Binary Neutron Star Mergers Yun-Peng Li, Zhi-Lin Chen, Da-Bin Lin, En-Wei Liang arXiv:2404.19340v1 Announce Type: new Abstract: The merger of neutron star (NS)-NS binary can form different production of the compact remnant, among which the supramassive NS (SMNS) could create an internal plateau and the followed steep decay marks the collapse of the SMNS. The proportion of SMNS and the corresponding collapse-time are often used to constrain the NS equation of state (EoS). This paper revisits this topic by considering the effect of an accretion disk on the compact remnant, which isRead More →

Strength in numbers: A multiphase wind model with multiple cloud populations C. Nikolis, M. Gronke arXiv:2404.19380v1 Announce Type: new Abstract: Galactic outflows have a multiphase nature making them challenging to model analytically. Many previous studies have tried to produce models that come closer to reality. In this work, we continue these efforts and describe the interaction of the hot wind fluid with multiple cold cloud populations, with their number density determined by different probability density functions. To do so, we introduced realistic cloud-wind interaction source terms and a time-varying cooling area. We find that the model reproduces well results from small-scale hydrodynamic simulations, but exhibitsRead More →

Comparative Mid-Infrared Spectroscopy of Dark, Primitive Asteroids: Does Shared Taxonomic Class Indicate Shared Silicate Composition? Oriel A. Humes, Audrey C. Martin, Cristina A. Thomas, Joshua P. Emery arXiv:2404.19388v1 Announce Type: new Abstract: Primitive asteroids with low albedos and red slopes in the visible and near infrared (VNIR) are found in both the Main Belt and the Jupiter Trojan clouds. In order to determine whether the VNIR spectral similarities of primitive Main Belt asteroids and Jupiter Trojans are reflective of a true compositional similarity, we compare the mid-infrared silicate emission features of Main Belt and Jupiter Trojan asteroids. Using archival data from the Spitzer Space Telescope’sRead More →

EL meteorites do date the giant planet instability Chrysa Avdellidou, Marco Delbo, David Nesvorny, Kevin J. Walsh, Alessandro Morbidelli arXiv:2404.19390v1 Announce Type: new Abstract: In our recent work, we combined dynamical simulations, meteoritic data and thermal models as well as asteroid observations to argue that the current parent body of the EL meteorites was implanted into the asteroid belt not earlier than 60 Myr after the beginning of the Solar System and that the most likely capture mechanism was the giant planet orbital instability. In the study “The link between Athor and EL meteorites does not constrain the timing of the giant planet instability” thatRead More →