Related papers: Cyg X-3: can the compact object be a black hole?
Black hole (BH) X-ray binaries (XRBs) are X-ray luminous binary systems comprising a BH accreting matter from a companion star. Understanding their origins sheds light on the still not well understood physics of BH formation. M33 X-7 hosts…
High-resolution simulations of supermassive black holes in isolated galaxies have suggested the importance of short (~10 Myr) episodes of rapid accretion caused by interactions between the black hole and massive dense clouds within the…
In this paper we study the wind accretion onto a rotating black hole in the close binary system harboring a young massive star. It is shown that the angular momentum of the accreted stellar wind material is not sufficient for the formation…
Most black holes (BHs) formed in collapsing stars have low spin, though some are expected to acquire a magnetic accretion disk during the collapse. While such BH disks can launch magnetically driven winds, their physics and observational…
We compare the performance of the popular Bondi-Hoyle-Lyttleton (BHL) accretion scheme with a simple mass-flux scheme applied to stellar-mass black holes (BHs) across six levels of increasing spatial resolution. Simulating the formation of…
The recent distance determination allowed precise estimation of the orbital parameters of Cyg X-1, which contains a massive 14.8 Msun BH with a 19.2 Msun O star companion. This system appears to be the clearest example of a potential…
The nature of the seeds of the observed high-z super-massive black holes (SMBH) is unknown. Although different options have been proposed, involving e.g. intermediate mass direct collapse black holes, BH remnants of massive stars remain the…
15 years of XMM-Newton observations have established that ultra-fast, highly ionized winds are common in radio-quiet AGN. A simple theory of Eddington-limited accretion correctly predicts the typical velocity (~0.1c) and high ionization of…
The characteristics of black-hole X-ray binaries can be used to obtain information about their evolutionary history and the process of black-hole formation. In this paper I focus on systems with donor masses lower than the inferred…
The accretion process in a typical S-type symbiotic star, targeting~AG Draconis, is investigated through 3D hydrodynamical simulations using the FLASH code. Regardless of the wind velocity of the giant star, an accretion disk surrounding…
The first stars formed over five orders of magnitude in mass by accretion in primordial dark matter halos. We study the evolution of massive, very massive and supermassive primordial (Pop III) stars over nine orders of magnitude in…
Super-Eddington accretion has been suggested as a possible formation pathway of $10^9 \, M_\odot$ supermassive black holes (SMBHs) 800 Myr after the Big Bang. However, stellar feedback from BH seed progenitors and winds from BH accretion…
Cygnus X-3 is a microquasar consisting of an accreting compact object orbiting around a Wolf-Rayet star. It has been detected at radio frequencies and up to high-energy gamma rays (above 100 MeV). However, many models also predict a very…
We study near-infrared (JHK) and X-ray light curves of Cyg X-3 obtained with the 2.5-m telescope of the Caucasian Mountain Observatory of MSU SAI and collected from RXTE ASM and MAXI archives. The light curves in the X-ray and IR domains…
We perform a detailed study of the location of brightest cluster galaxies (BCGs) on the fundamental plane of black hole (BH) accretion, which is an empirical correlation between a BH X-ray and radio luminosity and mass supported by…
We present direct observational constraints on tachyons; particles with group velocity greater than $c$ in vacuum in a Lorentz invariant theory. Since tachyons may have no direct couplings to Standard Model particles, the most robust and…
The collapse of baryons into extremely massive stars with masses exceeding 10^4 M_Sun in a small fraction of protogalaxies at z > 10 is a promising candidate for the origin of supermassive black holes, some of which grow to a billion solar…
We have completed two years of photometric and spectroscopic monitoring of a large number of active galactic nuclei (AGNs) with very high accretion rates. In this paper, we report on the result of the second phase of the campaign, during…
We investigated the reported distances of Galactic black hole (BH) and neutron star low-mass X-ray binaries (LMXBs). Comparing the distances derived for the neutron stars CygX-2 and XTE J2123-058 using the observed Eddington limited…
We present the results of a systematic study of the formation and evolution of binaries containing black holes and normal-star companions with a wide range of masses. We first reexamine the standard formation scenario for close black-hole…