Ice Peeks out of a Cliffside on Mars The HiRISE (High-Resolution Imaging Science Experiment) camera on the Mars Reconnaissance Orbiter has captured another beauty. This time the image shows water ice peeking out from a cliffside on Mars. A layer of sediment obscures most of the ice, but fingers of it are visible. Mars likely had ancient oceans, and the remnants of all that water are hidden as ice. It’s mostly buried in the planet’s crust. In this image, it’s under a thick layer of sediment. The image is from Mars’ Milankovic Crater, a prominent impact crater that sits alone to the north of OlympusRead More →

Hypercritical Accretion for Black Hole High Spin in Cygnus X-1. (arXiv:2201.05611v1 [astro-ph.HE]) <a href="">Ying Qin</a>, <a href="">Xinwen Shu</a>, <a href="">Shuangxi Yi</a>, <a href="">Yuan-Zhu Wang</a> Recent observations of AdLIGO and Virgo have shown that the spin measurements in binary black hole (BH) systems are typically small, which is consistent with the predictions by the classical isolated binary evolution channel. In this standard formation channel, the progenitor of the first-born BH is assumed to have efficient angular momentum transport. The BH spins in high-mass X-ray binaries (HMXBs), however, have been found consistently to be extremely high. In order to explain the high BH spins, the inefficient angularRead More →

Systematic evaluation of variability detection methods for eROSITA. (arXiv:2106.14529v2 [astro-ph.HE] UPDATED) <a href="">Johannes Buchner</a>, <a href="">Thomas Boller</a>, <a href="">David Bogensberger</a>, <a href="">Adam Malyali</a>, <a href="">Kirpal Nandra</a>, <a href="">Joern Wilms</a>, <a href="">Tom Dwelly</a>, <a href="">Teng Liu</a> The reliability of detecting source variability in sparsely and irregularly sampled X-ray light curves is investigated. This is motivated by the unprecedented survey capabilities of eROSITA onboard SRG, providing light curves for many thousand sources in its final-depth equatorial deep field survey. Four methods for detecting variability are evaluated: excess variance, amplitude maximum deviations, Bayesian blocks and a new Bayesian formulation of the excess variance. We judge the false detectionRead More →

Similarities and Differences in Accretion Flow Properties between GRS 1915+105 and IGR J17091-3624: a Case Study. (arXiv:2101.11854v2 [astro-ph.HE] UPDATED) <a href="">Anuvab Banerjee</a>, <a href="">Ayan Bhattacharjee</a>, <a href="">Dipak Debnath</a>, <a href="">Sandip K. Chakrabarti</a> We perform a comparative spectro-temporal analysis on the variability classes of GRS 1915+105 and IGR J17091-3624 to draw inferences regarding the underlying accretion flow mechanism. The $nu$, as well as C2 class Rossi X-Ray Timing Explorer observation, have been considered for analysis. We investigate the intensity variation of the source in different energy domains that correspond to different components of the accretion flow and infer the relative dominance of these flow components duringRead More →

Constraints on the abundance of primordial black holes with different mass distributions from lensing of fast radio bursts. (arXiv:2103.08510v3 [astro-ph.CO] UPDATED) <a href="">Huan Zhou</a>, <a href="">Zhengxiang Li</a>, <a href="">Zhiqi Huang</a>, <a href="">He Gao</a>, <a href="">Lu Huang</a> Primordial black holes (PBHs) has been considered to form a part of dark matter for a long time but the possibility has been poorly constrained over a wide mass range, including the stellar mass range ($1-100~M_{odot}$). However, due to the discovery of merger events of black hole binaries by LIGO-Virgo gravitational wave observatories, the interest for PBHs in the stellar mass window has been aroused again. Fast radio burstsRead More →

The ultimate performance of the Rasnik 3-point alignment system. (arXiv:2104.03601v6 [astro-ph.IM] UPDATED) <a href="">Harry van der Graaf</a>, <a href="">Alessandro Bertolini</a>, <a href="">Joris van Heijningen</a>, <a href="">Bram Bouwens</a>, <a href="">Nelson de Gaay Fortman</a>, <a href="">Tom van der Reep</a>, <a href="">Lennaert Otemann</a> The Rasnik system is a 3-point optical displacement monitor with sub-nanometer precision. The CCD-Rasnik alignment system was developed in 1993 for the monitoring of the alignment of the muon chambers of the ATLAS Muon Spectrometer at CERN. Since then, the development has continued as new CMOS imaging pixel chips became available. The system’s processes and parameters that limit the precision have been studied in detail.Read More →

Multi-scale Magnetic Fields in the Central Molecular Zone: Inference from the Gradient Technique. (arXiv:2105.03605v3 [astro-ph.GA] UPDATED) <a href="">Yue Hu</a>, <a href="">A. Lazarian</a>, <a href="">Q.Daniel Wang</a> The central molecular zone (CMZ) plays an essential role in regulating the nuclear ecosystem of our Galaxy. To get an insight into the magnetic fields of the CMZ, we employ the Gradient Technique (GT), which is rooted in the anisotropy of magnetohydrodynamic turbulence. Our analysis is based on the data of multiple wavelengths, including molecular emission lines, radio 1.4 GHz continuum image, and Herschel 70 $mu$m image, as well as ionized [Ne II] and Paschen-alpha emissions. The results are comparedRead More →

Z-portal Continuum Dark Matter. (arXiv:2105.14023v3 [hep-ph] UPDATED) <a href="">Csaba Cs&#xe1;ki</a>, <a href="">Sungwoo Hong</a>, <a href="">Gowri Kurup</a>, <a href="">Seung J. Lee</a>, <a href="">Maxim Perelstein</a>, <a href="">Wei Xue</a> We examine the possibility that dark matter (DM) consists of a gapped continuum, rather than ordinary particles. A Weakly-Interacting Continuum (WIC) model, coupled to the Standard Model via a Z-portal, provides an explicit realization of this idea. The thermal DM relic density in this model is naturally consistent with observations, providing a continuum counterpart of the “WIMP miracle”. Direct detection cross sections are strongly suppressed compared to ordinary Z-portal WIMP, thanks to a unique effect of the continuum kinematics.Read More →

Structure of conformal gravity in the presence of a scale breaking scalar field. (arXiv:2105.14679v3 [gr-qc] UPDATED) <a href="">Philip D. Mannheim</a> We revisit the structure of conformal gravity in the presence of a c-number, conformally coupled, long range, macroscopic scalar field. And in the static, spherically symmetric case discuss two classes of exact exterior solutions, in one of which the scalar field has a constant value and in the other, which is due to Brihaye and Verbin, it has a radial dependence. In light of these two solutions Horne and then Hobson and Lasenby raised the concern that the fitting of conformal gravity to galactic rotationRead More →

The nozzle shock in tidal disruption events. (arXiv:2106.01376v2 [astro-ph.HE] UPDATED) <a href="">Cl&#xe9;ment Bonnerot</a>, <a href="">Wenbin Lu</a> Tidal disruption events (TDEs) occur when a star gets torn apart by the strong tidal forces of a supermassive black hole, which results in the formation of a debris stream that partly falls back towards the compact object. This gas moves along inclined orbital planes that intersect near pericenter, resulting in a so-called “nozzle shock”. We perform the first dedicated study of this interaction, making use of a two-dimensional simulation that follows the transverse gas evolution inside a given section of stream. This numerical approach circumvents the lack ofRead More →

Primordial Black Hole Merger Rate in Self-Interacting Dark Matter Halo Models. (arXiv:2106.06265v2 [astro-ph.CO] UPDATED) <a href="">Saeed Fakhry</a>, <a href="">Mahdi Naseri</a>, <a href="">Javad T. Firouzjaee</a>, <a href="">Mehrdad Farhoudi</a> We study the merger rate of primordial black holes (PBHs) in the self-interacting dark matter (SIDM) halo models. To explore a numerical description for the density profile of the SIDM halo models, we use the result of a previously performed simulation for the SIDM halo models with $sigma/m=10~cm^{2}g^{-1}$. We also propose a concentration-mass-time relation that can explain the evolution of the halo density profile related to the SIDM models. Furthermore, we investigate the encounter condition of PBHs thatRead More →

The Gravitational Wave Universe Toolbox: A software package to simulate observation of the Gravitational Wave Universe with different detectors. (arXiv:2106.13662v2 [astro-ph.HE] UPDATED) <a href="">Shu-Xu Yi</a>, <a href="">Gijs Nelemans</a>, <a href="">Christiaan Brinkerink</a>, <a href="">Zuzanna Kostrzewa-Rutkowska</a>, <a href="">Sjoerd T. Timmer</a>, <a href="">Fiorenzo Stoppa</a>, <a href="">Elena M. Rossi</a>, <a href="">Simon F. Portegies Zwart</a> Context. As the importance of Gravitational Wave (GW) Astrophysics increases rapidly, astronomers in different fields and with different backgrounds can have the need to get a quick idea of which GW source populations can be detected by which detectors and with what measurement uncertainties. Aims. The GW-Toolbox is an easy-to-use, flexible tool to simulate observationsRead More →

High-resolution VLBI observations of and modelling the radio emission from the TDE AT2019dsg. (arXiv:2106.15799v2 [astro-ph.HE] UPDATED) <a href="">Prashanth Mohan</a>, <a href="">Tao An</a>, <a href="">Yingkang Zhang</a>, <a href="">Jun Yang</a>, <a href="">Xiaolong Yang</a>, <a href="">Ailing Wang</a> A tidal disruption event (TDE) involves the shredding of a star in the proximity of a supermassive black hole (SMBH). The nearby ($approx$230 Mpc) relatively radio-quiet, thermal emission dominated source AT2019dsg is the first TDE with a potential neutrino association. The origin of non-thermal emission remains inconclusive; possibilities include a relativistic jet or a sub-relativistic outflow. Distinguishing between them can address neutrino production mechanisms. High-resolution very long baseline interferometry 5-GHz observationsRead More →

BeyondPlanck XV. Polarized foreground emission between 30 and 70 GHz. (arXiv:2011.08503v2 [astro-ph.CO] UPDATED) <a href="">T. L. Svalheim</a>, <a href="">K. J. Andersen</a>, <a href="">R. Aurlien</a>, <a href="">R. Banerji</a>, <a href="">M. Bersanelli</a>, <a href="">S. Bertocco</a>, <a href="">M. Brilenkov</a>, <a href="">M. Carbone</a>, <a href="">L. P. L. Colombo</a>, <a href="">H. K. Eriksen</a>, <a href="">M. K. Foss</a>, <a href="">C. Franceschet</a>, <a href="">U. Fuskeland</a>, <a href="">S. Galeotta</a>, <a href="">M. Galloway</a>, <a href="">S. Gerakakis</a>, <a href="">E. Gjerl&#xf8;w</a>, <a href="">B. Hensley</a>, <a href="">D. Herman</a>, <a href="">M. Iacobellis</a>, <a href="">M. Ieronymaki</a>, <a href="">H. T. Ihle</a>, <a href="">J. B. Jewell</a>, <a href="">A. Karakci</a>, <a href="">E. Keih&#xe4;nen</a>, <a href="">R. Keskitalo</a>, <a href="">G. Maggio</a>, <a href="">D. Maino</a>,Read More →

The BINGO Project V: Further steps in Component Separation and Bispectrum Analysis. (arXiv:2107.01637v2 [astro-ph.CO] UPDATED) <a href="">Karin S. F. Fornazier</a>, <a href="">Filipe B. Abdalla</a>, <a href="">Mathieu Remazeilles</a>, <a href="">Jordany Vieira</a>, <a href="">Alessandro Marins</a>, <a href="">Elcio Abdalla</a>, <a href="">Larissa Santos</a>, <a href="">Jacques Delabrouille</a>, <a href="">Eduardo Mericia</a>, <a href="">Ricardo G. Landim</a>, <a href="">Elisa G. M. Ferreira</a>, <a href="">Luciano Barosi</a>, <a href="">Amilcar R. Queiroz</a>, <a href="">Thyrso Villela</a>, <a href="">Bin Wang</a>, <a href="">Carlos A. Wuensche</a>, <a href="">Andre A. Costa</a>, <a href="">Vincenzo Liccardo</a>, <a href="">Camila Paiva Novaes</a>, <a href="">Michael W. Peel</a>, <a href="">Marcelo V. dos Santos</a>, <a href="">Jiajun Zhang</a> Observing the neutral hydrogen distribution across the Universe via redshifted 21cmRead More →

Testing the presence of a dormant black hole inside HR 6819. (arXiv:2107.08930v3 [astro-ph.SR] UPDATED) <a href="">A. Romagnolo</a>, <a href="">A. Olejak</a>, <a href="">A. Hypki</a>, <a href="">G. Wiktorowicz</a>, <a href="">K. Belczynski</a> HR 6819 was reported in Rivinius et al. (2020) to be a triple system with a non-accreting black hole (BH). The inner binary system was defined as a B3 III type star and a dormant BH. The period of the inner binary was estimated to be around 40 days with an eccentricity between 0.02 and 0.04. As the inner binary is not resolved, the third component may actually be just spatially coinciding with the inner binary.Read More →

Solar system peculiar motion from the Hubble diagram of quasars and testing the Cosmological Principle. (arXiv:2107.09390v2 [astro-ph.CO] UPDATED) <a href="">Ashok K. Singal</a> We determine here peculiar motion of the Solar system, first time from the $m-z$ Hubble diagram of quasars. Observer’s peculiar motion causes a systematic shift in the $m-z$ plane between sources lying along the velocity vector and those in the opposite direction, providing a measure of the peculiar velocity. Accordingly, from a sample of $sim 1.2 times 10^5$ mid-infrared quasars with measured spectroscopic redshifts, we arrive at a peculiar velocity $sim 22$ times larger than that from the CMBR dipole, but direction matchingRead More →

The Regulated NiCu Cycles with the new $^{57}$Cu(p,$gamma$)$^{58}$Zn reaction rate and the Influence on Type-I X-Ray Bursts: GS 1826$-$24 Clocked Burster. (arXiv:2107.11552v2 [astro-ph.HE] UPDATED) <a href="">Yi Hua Lam</a>, <a href="">Ning Lu</a>, <a href="">Alexander Heger</a>, <a href="">Adam Michael Jacobs</a>, <a href="">Nadezda A. Smirnova</a>, <a href="">Teresa Kurtukian Nieto</a>, <a href="">Zac Johnston</a>, <a href="">Shigeru Kubono</a> During the X-ray bursts of GS 1826$-$24, “clocked burster”, the nuclear reaction flow that surges through the rapid-proton capture process path has to pass through the NiCu cycles before reaching the ZnGa cycles that moderate the further extent of hydrogen burning in the region above germanium and selenium isotopes. The $^{57}$Cu(p,$gamma$)$^{58}$Zn reaction locatedRead More →

Differentiating Dilatons from Axions by their mixing with photons. (arXiv:2107.11594v2 [hep-ph] UPDATED) <a href="">Ankur Chaubey</a>, <a href="">Manoj K. Jaiswal</a>, <a href="">Damini Singh</a>, <a href="">Venktesh Singh</a>, <a href="">Avijit K. Ganguly</a> According to the model ($Lambda$CDM), based on deep cosmological observations, the current universe is constituted of 5$%$ baryonic matter and 25 $%$ non-baryonic cold dark matter (of speculative origin). These include quanta of scalar filed like dilaton($phi$) of scale symmetry origin and quanta of pseudoscalar field of extra standard model symmetry ( Peccei-Quinn) origin, like axion ($phi’$). These fields couple to di-photons through dim-5 operators. In magnetized medium, they in principle can interact with the threeRead More →

Constraining spinning primordial black holes with global 21-cm signal. (arXiv:2107.12358v2 [astro-ph.CO] UPDATED) <a href="">Pravin Kumar Natwariya</a>, <a href="">Alekha C. Nayak</a>, <a href="">Tripurari Srivastava</a> We study the upper projected bounds on the dark matter fraction in the form of the primordial black holes (PBHs) with a non-zero spin by using the absorption feature in the global 21-cm signal at redshift z ~ 17. The mass and spin are fundamental properties of a black hole, and they can substantially affect the evaporation rate of the black hole. The evaporating black hole can inject energy into the intergalactic medium and heat the gas. Subsequently, it can modify theRead More →