RAS_WEB (Page 35)

The open-source sunbather code: modeling escaping planetary atmospheres and their transit spectra Dion Linssen, Jim Shih, Morgan MacLeod, Antonija Oklopv{c}i’c arXiv:2404.12775v1 Announce Type: new Abstract: Atmospheric escape is thought to significantly influence the evolution of exoplanets, especially for sub-Jupiter planets on short orbital periods. Theoretical models predict that hydrodynamic escape could erode the atmospheres of such gaseous planets, leaving only a rocky core. Deriving atmospheric mass-loss rates from observations is necessary to check these predictions. One of the ways to obtain mass-loss rate estimates is to fit transit spectra of the 10830 {AA} helium or UV metal lines with Parker wind models. We aim toRead More →

Inflation, the Hubble Tension and Early Dark Energy: an alternative overview William Giar`e arXiv:2404.12779v1 Announce Type: new Abstract: I review and discuss the possible implications for inflation resulting from considering new physics in light of the Hubble tension. My study is motivated by a simple argument that the constraints on inflationary parameters, most typically the spectral index $n_s$, depend to some extent on the cosmological framework. To avoid broadening the uncertainties resulting from marginalizing over additional parameters (typical in many alternative models), I first adopt the same alternative viewpoint of previous studies and analyze what happens if a physical theory can fix extra parameters toRead More →

Making the invisible visible: Magnetic fields in accretion flows revealed by X-ray polarization Samuel Barnier, Chris Done arXiv:2404.12815v1 Announce Type: new Abstract: Large scale, strong magnetic fields are often evoked in black hole accretion flows, for jet launching in the low/hard state and to circumvent the thermal instability in the high/soft state. Here we show how these ideas are strongly challenged by X-ray polarization measurements from IXPE. Quite general arguments show that equipartition fields in the accretion flow should be of order $10^{6-8}$ G. These produce substantial Faraday rotation and/or depolarization for photons escaping the flow in the 2-8 keV IXPE bandpass, which is notRead More →

Distinguishing radiation mechanisms and particle populations in blazar jets through long-term multi-band monitoring with RINGO3 and Fermi Callum McCall, Helen Jermak, Iain A. Steele, Iv’an Agudo, Ulisses Barres de Almeida, Talvikki Hovatta, Gavin P. Lamb, Elina Lindfors, Carole Mundell arXiv:2404.12835v1 Announce Type: new Abstract: We present the results of seven years of multicolour photometric monitoring of a sample of 31 $gamma$-ray bright blazars using the RINGO3 polarimeter on the Liverpool Telescope from 2013–2020. We explore the relationships between simultaneous observations of flux in three optical wavebands along with Fermi $gamma$-ray data in order to explore the radiation mechanisms and particle populations in blazar jets. WeRead More →

A comprehensive study of compact stars with dark matter Mikel F. Barbat, J"urgen Schaffner-Bielich, Laura Tolos arXiv:2404.12875v1 Announce Type: new Abstract: We present a comprehensive study of compact stars admixed with non-self annihilating self-interacting fermionic dark matter, delineating the dependence on the nuclear equation of state by considering the two limiting parametrized equations of state for neutron star matter obtained by smoothly matching the low-density chiral effective theory and the high-density perturbative QCD. These two parametrizations are the limiting cases of a wide variety of smooth equations of state, i.e. the softest and stiffest possible one without a phase transition, that generate masses and radiiRead More →

SDSS J222428.53+261423.2: unique emission lines properties unveil a sub-kiloparsec dual AGN candidate Qi Zheng, XueGuang Zhang, QiRong Yuan, Paola Severgnini, Cristian Vignali arXiv:2404.12911v1 Announce Type: new Abstract: In this paper, we presented a detailed analysis of the Sloan Digital Sky Survey optical spectrum of a new sub-kpc scale dual AGN candidate SDSS J222428.53+261423.2 (=SDSS J2224). The target is one of the few AGNs with all the optical narrow emission lines characterized by double-peaked profiles and with peak separations in velocity units of about 930 km/s. If the double-peaked narrow emission lines (DPNELs) are due to a dual AGN in obj, the estimated physical separation betweenRead More →

Insights from the Gaussian Processes Method for the FRB-associated X-ray Burst of SGR 1935+2154 Ruijing Tang, Dahai Yan, Haiyun Zhang, Qingchang Zhao, Lian Tao, Chengkui Li, Mingyu Ge, Xiaobo Li, Qianqing Yin, Ce Cai arXiv:2404.12976v1 Announce Type: new Abstract: Gaussian processes method is employed to analyze the light curves of bursts detected by Insight-HXMT, NICER, and GECAM from SGR 1935+2154 between 2020 to 2022. It is found that a stochastically driven damped simple harmonic oscillator (SHO) is necessary to capture the characteristics of the X-ray bursts. Variability timescale of the X-ray bursts, corresponding to the broken frequencies in the SHO power spectral densities (PSDs), areRead More →

Buoyancy glitches in pulsating stars revisited Margarida S. Cunha, Yuri C. Damasceno, Juliana Amaral, Anselmo Falorca, J{o}rgen Christensen-Dalsgaard, Pedro P. Avelino arXiv:2404.12992v1 Announce Type: new Abstract: Sharp structural variations induce specific signatures on stellar pulsations that can be studied to infer localised information on the stratification of the star. This information is key to improve our understanding of the physical processes that lead to the structural variations and how to model them. Here we revisit and extend the analysis of the signature of different types of buoyancy glitches in gravity-mode and mixed-mode pulsators presented in earlier works, including glitches with step-like, Gaussian-like, and Dirac-$delta$-like shapes.Read More →

A multigrain-multilayer astrochemical model with variable desorption energy for surface species Juris Kalvans, Aija Kalnina, Kristaps Veitners arXiv:2404.13011v1 Announce Type: new Abstract: Context. Interstellar surface chemistry is a complex process that occurs in icy layers accumulated onto grains of different sizes. Efficiency of surface processes often depends on the immediate environment of adsorbed molecules. Aims. We investigate how gas-grain chemistry changes when surface molecule desorption is made explicitly dependent to the molecular binding energy, which is modified, depending on the properties of the surface. Methods. Molecular binding energy changes gradually for three different environments – bare grain, where polar, water-dominated ices and non-polar, carbon monoxide-dominatedRead More →

Cliff collapse on Comet 67P/Churyumov-Gerasimenko — II. Imhotep and Hathor Bj"orn J. R. Davidsson arXiv:2404.13030v1 Announce Type: new Abstract: Cliff collapses on Comet 67P/Churyumov-Gerasimenko expose relatively pristine nucleus matter and offer rare opportunities to characterise ice-rich comet material. Here, Microwave Instrument for emph{Rosetta} Orbiter (MIRO) observations of two collapsed or crumbling cliffs in the Imhotep and Hathor regions have been assembled. The empirical diurnal antenna temperature curves are analysed with thermophysical and radiative transfer models in order to place constraints on the physical properties and degrees of stratification in the near-surface material. The Imhotep site consists of an exposed dust/water-ice mixture with thermal inertia 100-$160,mathrm{J,m^{-2},K^{-1},s^{-1/2}}$,Read More →

OGLE-2015-BLG-0845L: A low-mass M dwarf from the microlensing parallax and xallarap effects Zhecheng Hu, Wei Zhu, Andrew Gould, Andrzej Udalski, Takahiro Sumi, Ping Chen, Sebastiano Calchi Novati, Jennifer C. Yee, Charles A. Beichman, Geoffery Bryden, Sean Carey, Michael Fausnaugh, B. Scott Gaudi, Calen B. Henderson, Yossi Shvartzvald, Benjamin Wibking, Przemek Mr’oz, Jan Skowron, Radoslaw Poleski, Michae{l} K. Szyma’nski, Igor Soszyn’ski, Pawe{l} Pietrukowicz, Szymon Koz{l}owski, Krzysztof Ulaczyk, Krzysztof A. Rybicki, Patryk Iwanek, Marcin Wrona, Mariusz Gromadzki, Fumio Abe, Richard Barry, David P. Bennett, Aparna Bhattacharya, Ian A. Bond, Hirosane Fujii, Akihiko Fukui, Ryusei Hamada, Yuki Hirao, Stela Ishitani Silva, Yoshitaka Itow, Rintaro Kirikawa, Naoki Koshimoto, YutakaRead More →

The James Webb Interferometer: Space-based interferometric detections of PDS 70 b and c at 4.8 $mu$m Dori Blakely, Doug Johnstone, Gabriele Cugno, Anand Sivaramakrishnan, Peter Tuthill, Ruobing Dong, Benjamin J. S. Pope, Lo"ic Albert, Max Charles, Rachel A. Cooper, Matthew De Furio, Louis Desdoigts, Ren’e Doyon, Logan Francis, Alexandra Z. Greenbaum, David Lafreni`ere, James P. Lloyd, Michael R. Meyer, Laurent Pueyo, Shrishmoy Ray, Joel S’anchez-Berm’udez, Anthony Soulain, Deepashri Thatte, Thomas Vandal arXiv:2404.13032v1 Announce Type: new Abstract: We observed the planet-hosting system PDS 70 with the James Webb Interferometer, JWST’s Aperture Masking Interferometric (AMI) mode within NIRISS. Observing with the F480M filter centered at 4.8 $mu$m,Read More →

Dynamical formation of Gaia BH3 in the progenitor globular cluster of the ED-2 stream Daniel Mar’in Pina, Sara Rastello, Mark Gieles, Kyle Kremer, Laura Fitzgerald, Bruno Rando arXiv:2404.13036v1 Announce Type: new Abstract: Context. The star-black hole (S-BH) binary discovered by the Gaia Collaboration – Gaia BH3 – is chemically and kinematically associated with the metal-poor ED-2 stream in the Milky Way halo. Aims. We explore the possibility that Gaia BH3 was assembled dynamically in the progenitor globular cluster (GC) of the ED-2 stream. Methods. We use a public suite of star-by-star dynamical Monte Carlo models by Kremer et al. (2020) to identify S-BH binaries inRead More →

NIRSpec View of the Appearance and Evolution of Balmer Breaks and the Transition from Bursty to Smooth Star Formation Histories from Deep Within the Epoch of Reionization to Cosmic Noon Danial Langeroodi, Jens Hjorth arXiv:2404.13045v1 Announce Type: new Abstract: Theoretical models and observational evidence suggest that high-redshift galaxies grow under the bursty mode of star formation, with large temporal star formation rate (SFR) fluctuations around some mean value. From an observational perspective, it has not been clear at which redshift and stellar population characteristics the transition from bursty to smooth star formation occurs. Here, we investigate these using a uniformly reduced sample of NIRSpec prismRead More →

Formation of a $33,M_{odot}$ black hole in a low-metallicity binary Kareem El-Badry arXiv:2404.13047v1 Announce Type: new Abstract: A $33,M_odot$ black hole (BH) was recently discovered in an 11.6-year binary only 590 pc from the Sun. The system, Gaia BH3, contains a $0.8,M_odot$ low-metallicity giant ($rm [M/H]=-2.2$) and is kinematically part of the Galactic halo, suggesting that the BH formed from a low-metallicity massive star. I show that orbits similar to that of Gaia BH3 are naturally produced through isolated binary evolution. The system’s period and eccentricity can result from a broad range of initial orbits with a modest natal kick ($v_{rm kick}lesssim 75,rm km,s^{-1}$) toRead More →