RAS_WEB (Page 30)

Non-Gaussianity from primordial black holes Jinn-Ouk Gong, Naoya Kitajima arXiv:2404.08318v1 Announce Type: new Abstract: We study the effects of non-Gaussianity from primordial black holes (PBHs). The formation of PBHs is in general a rare event and the number of PBHs fluctuates following the Poisson distribution function, which is independent from the pre-existing inflationary adiabatic fluctuations. Such fluctuations can dominate over the adiabatic mode on small scales. We focus on the non-Gaussianity of matter density fluctuations induced by the Poisson fluctuation of PBHs and discuss the potentially observable consequences such as the skewness, kurtosis and the scale-dependent bias.arXiv:2404.08318v1 Announce Type: new Abstract: We study the effectsRead More →

Estimate of force noise from electrostatic patch potentials in LISA Pathfinder Stefano Vitale, Lorenzo Sala, Valerio Ferroni, William Joseph Weber arXiv:2404.08340v1 Announce Type: new Abstract: This paper discusses force noise in LISA and LISA Pathfinder arising from the interaction of patch potentials on the test mass and surrounding electrode housing surfaces with their own temporal fluctuations. We aim to estimate the contribution of this phenomenon to the force noise detected in LISA Pathfinder in excess of the background from Brownian motion. We introduce a model of that approximates the interacting test mass and housing surfaces as concentric spheres, treating patch potentials as isotropic stochastic GaussianRead More →

Evidence of the gamma-ray counterpart from nova FM Cir with F ermi-LAT H. H. Wang, H. D. Yan, L. C. -C. Lin, J. Takata, P. -H. T. Tam arXiv:2404.08409v1 Announce Type: new Abstract: We report the analysis results of X-ray and gamma-ray data of the nova FM Cir taken by Swift and Fermi-LAT. The gamma-ray emission from FM Cir can be identified with a significance level of 3sigma within 40 days after the nova eruption (2018 January 19) while we bin the light curve per day. The significance can further exceed 4 sigma confidence level if we accumulate longer time (i.e., 20 days) to binRead More →

Formation of primordial black hole binaries and their merger rates Martti Raidal, Ville Vaskonen, Hardi Veerm"ae arXiv:2404.08416v1 Announce Type: new Abstract: We review the theory behind the formation of primordial black hole binaries and their merger rates. We consider the binary formation in the early and late Universe, emphasising the former as it gives the dominant contribution of the present primordial black hole merger rate. The binaries formed in the early Universe are highly eccentric and get easily disrupted by interactions with other primordial black holes. We discuss in detail how the suppression of the merger rate arising from such interactions can be estimated andRead More →

MINCE II. Neutron capture elements P. Franc{c}ois, G. Cescutti, P. Bonifacio, E. Caffau, L. Monaco, M. Steffen, J. Puschnig, F. Calura, S. Cristallo, P. Di Marcantonio, V. Dobrovolskas, M. Franchini, A. J. Gallagher, C. J. Hansen, A. Korn, A. Kuvinskas, R. Lallement, L. Lombardo, F. Lucertini, L. Magrini, A. M. Matas Pinto, F. Matteucci, A. Mucciarelli, L. Sbordone, M. Spite, E. Spitoni, M. Valentini arXiv:2404.08418v1 Announce Type: new Abstract: The MINCE (Measuring at Intermediate metallicity Neutron-Capture Elements) project aims to gather the abundances of neutron-capture elements but also of light elements and iron peak elements in a large sample of giant stars in this metallicityRead More →

Great Observatory for Long Wavelengths (GO-LoW) NIAC Phase I Final Report Mary Knapp, Lenny Paritsky, Ekaterina Kononov, Melodie M. Kao arXiv:2404.08432v1 Announce Type: new Abstract: The low-frequency sky below $sim$15 MHz (20 m) is obscured by the Earth’s ionosphere, the layer of charged particles above the neutral atmosphere. Single spacecraft have made measurements in this band, but cannot achieve high or even moderate angular resolution because a telescope’s resolution ($theta$) is set by $theta = lambda/D$, where $lambda$ is the wavelength and $D$ is the telescope diameter. For wavelengths that range from tens of meters to kilometers, a telescope must be hundreds of meters toRead More →

Equilibrium tides and magnetic activity in stars with close-by massive planets. The intriguing case of WASP-18 A. F. Lanza (INAF-Catania, Italy), S. N. Breton (INAF-Catania, Italy) arXiv:2404.08439v1 Announce Type: new Abstract: WASP-18 is an F6V star that hosts a planet with a mass of about 10 Jupiter masses and an orbital period of 0.94 days. In spite of its relatively fast rotation and young age, the star remains undetected in X-rays, thus implying a very low level of magnetic activity. To account for such unexpected properties, we propose a mechanism that modifies the internal stratification and the photospheric magnetic activity of a late-type main sequenceRead More →

Fast giant flares in discs around supermassive black holes G. V. Lipunova, A. S. Tavleev, K. L. Malanchev arXiv:2404.08441v1 Announce Type: new Abstract: We study the thermal stability of non-self-gravitating turbulent $alpha$ discs around supermassive black holes (SMBHs) to test a new type of high-amplitude active galactic nuclei (AGN) flares. On calculating discs structures, we compute the critical points of stability curves for discs around SMBH, which cover a wide range of accretion rates and resemble the shape of a $xi$ curve. We find that there are values of the disc parameters that favour the transition of a disc ring from a recombined cool stateRead More →

21cm signal from Dark Ages collapsing halos with detailed molecular cooling treatment Hugo Plombat, Denis Puy arXiv:2404.08479v1 Announce Type: new Abstract: Context. In order to understand the formation of the first stars, which set the transition between the Dark Ages and Cosmic Dawn epochs, it is necessary to provide a detailed description of the physics at work within the first clouds of gas which, during their gravitational collapse, will set the conditions for stars to be form through the mechanism of thermal instability. Aims. Our objective is to study in detail the molecular cooling of gas in the halos preceding the formation of the firstRead More →

A generalizable method for estimating meteor shower false positives Patrick M. Shober, Jeremie Vaubaillon arXiv:2404.08507v1 Announce Type: new Abstract: Context. The determination of meteor shower or parent body associations is inherently a statistical problem. Traditional methods, primarily the similarity discriminants, have limitations, particularly in handling the increasing volume and complexity of meteoroid orbit data. Aims. We aim to introduce a new, more statistically robust and generalizable method for estimating false positive detections in meteor shower identification, leveraging Kernel Density Estimation (KDE). Methods. Utilizing a dataset of 824 fireballs observed by the European Fireball Network, we apply a multivariate Gaussian kernel within KDE and z-score dataRead More →

Relativistic SZ temperatures and hydrostatic mass bias for massive clusters in the FLAMINGO simulations Scott T. Kay, Joey Braspenning, Jens Chluba, John C. Helly, Roi Kugel, Matthieu Schaller, Joop Schaye arXiv:2404.08539v1 Announce Type: new Abstract: The relativistic Sunyaev-Zel’dovich (SZ) effect can be used to measure intracluster gas temperatures independently of X-ray spectroscopy. Here, we use the large-volume FLAMINGO simulation suite to determine whether SZ $y$-weighted temperatures lead to more accurate hydrostatic mass estimates in massive ($M_{rm 500c} > 7.5times 10^{14},{rm M}_{odot}$) clusters than when using X-ray spectroscopic-like temperatures. We find this to be the case, on average. The median bias in the SZ mass atRead More →

Flashlights: Microlensing vs Stellar Variability of Transients in the Star Clusters of the Dragon Arc Sung Kei Li, Patrick L. Kelly, Jose M. Diego, Jeremy Lim, WenLei Chen, Amruth Alfred, Liliya L. R. Williams, Thomas J. Broadhurst, Ashish. K. Meena, Adi Zitrin, Alex Chow arXiv:2404.08571v1 Announce Type: new Abstract: We study the nature of transient events detected in the “Dragon Arc”, a star-forming galaxy at a redshift of $0.7251$ that is gravitationally lensed by the galaxy cluster Abell 370. In particular, we focus on a subset of ten transients that are identified as unresolved young star clusters in the deep broadband, F200LP, taken as partRead More →

A Radical Solution to the Hubble Tension Problem Timothy Clifton, Neil Hyatt arXiv:2404.08586v1 Announce Type: new Abstract: The Hubble tension has proven to be stubbornly persistent, despite widespread efforts to relax it. As a possible resolution of this problem we propose a radical alternative to the way in which cosmological models are viewed. Specifically, we consider building cosmological models from spaces that exhibit intrinsic symmetries, rather than as space-times with explicit symmetry. This change in perspective allows statistical homogeneity and isotropy to be maintained, while relaxing some strong mathematical constraints that the standard approach imposes. We show that a Hubble tension arises naturally in ourRead More →

Absolute dimensions of solar-type eclipsing binaries. NY Hya: A test for magnetic stellar evolution models T. C. Hinse, O. Bac{s}t"urk, J. Southworth, G. A. Feiden, J. Tregloan-Reed, V. B. Kostov, J. Livingston, E. M. Esmer, Mesut Y{i}lmaz, Selc{c}uk Yalc{c}{i}nkaya, c{S}eyma Torun, J. Vos, D. F. Evans, J. C. Morales, J. C. A. Wolf, E. H. Olsen, J. V. Clausen, B. E. Helt, C. T. K. L’y, O. Stahl, R. Wells, M. Herath, U. G. J{o}rgensen, M. Dominik, J. Skottfelt, N. Peixinho, P. Longa-Pe~na, Y. Kim, H. -E. Kim, T. S. Yoon, H. I. Alrebdi, E. E. Zotos arXiv:2404.08594v1 Announce Type: new Abstract: The binary starRead More →

Analytic approximations for massive close post-mass transfer binary systems Christoph Sch"urmann, Norbert Langer, Joana A. Kramer, Pablo Marchant, Chen Wang, Koushik Sen arXiv:2404.08612v1 Announce Type: new Abstract: Massive binary evolution models are needed to predict massive star populations in star forming galaxies, the supernova diversity, and the number and properties of gravitational wave sources. Such models are often computed using so called rapid binary evolution codes, which approximate the evolution of the binary components based on detailed single star models. However, about one third of the interacting massive binary stars undergo mass transfer during core hydrogen burning (Case A mass transfer), whose outcome is difficultRead More →

Exploring the borderline between stable mass transfer and mergers in close binary evolution Christoph Sch"urmann, Norbert Langer arXiv:2404.08615v1 Announce Type: new Abstract: The majority of massive stars reside in binary systems, which are expected to experience mass transfer during their evolution. However, so far the conditions under which mass transfer leads to a common envelope, and thus possibly to a merging of both stars, are not well understood. Main uncertainties arise from the possible swelling of the mass gainer, and from angular momentum loss from the binary system, during non-conservative mass transfer. We have computed a dense grid of detailed models of stars accreting massRead More →