Related papers: Formation and Evolution of Black Hole X-ray Transi…
The formation of ultra-compact X-ray binaries (UCXBs) has not been well understood. Previous works show that ultra-short orbital periods ($<1$ hr) may be reached through mass transfer driven by magnetic braking in normal…
Black hole X-ray binaries are transient probably because their discs are subject to the same thermal-viscous instability which is present in dwarf nova binary systems. I discuss applications of the dwarf-nova instability model to transient,…
Tracking the evolution of high redshift seed black hole masses to late times, we examine the observable signatures today. These massive initial black hole seeds form at extremely high redshifts from the direct collapse of pre-galactic gas…
We present a quantitative study on the properties at death of fast-rotating massive stars evolved at low-metallicity, objects that are proposed as likely progenitors of long-duration gamma-ray bursts (LGRBs). We perform 1D+rotation…
Mass distribution of black holes in low-mass X-ray binaries previously suggested the existence of a $ \sim 2-5M_{\odot} $ mass gap between the most massive neutron stars and the least massive black holes, while some recent evidence appears…
We discuss a model for the early assembly of supermassive black holes (SMBHs) at the center of galaxies that trace their hierarchical build-up far up in the dark halo `merger tree'. Motivated by the observations of luminous quasars around…
We investigate the evolution of high redshift seed black hole masses at late times and their observational signatures. The massive black hole seeds studied here form at extremely high redshifts from the direct collapse of pre-galactic gas…
Observed spectra of Active Galactic Nuclei (AGN) and luminous X-ray binaries in our Galaxy suggest that both hot (~10^9 K) and cold (~10^6 K) plasma components exist close to the central accreting black hole. Hard X-ray component of the…
Binaries in which a massive donor star undergoes an extended ($\gtrsim$ kyr) phase of stable mass transfer onto a black hole (BH) accretor offer a promising channel for creating LIGO gravitational wave sources. However, in many systems the…
Recent N-body simulations show that the formation of a present-day, galaxy sized dark matter halo in the CDM cosmogony in general consists of an early fast collapse phase, during which the potential associated with a halo is established,…
Black-hole (BH) high-mass X-ray binary (HMXB) systems are likely to be the progenitors of BH-BH mergers detected by LIGO/Virgo/KAGRA (LVK). Yet merging BHs reach higher masses ($\sim 100M_{\odot}$) than BHs in HMXBs ($\sim 20 M_{\odot}$)…
Recently, several non-interacting black hole-stellar binaries have been identified in Gaia data. For example, Gaia BH1, where a Sun-like star is in a moderate eccentricity (e=0.44), 185-day orbit around a black hole. This orbit is difficult…
A binary in which a slightly evolved star starts mass transfer to a neutron star can evolve towards ultra-short orbital periods under the influence of magnetic braking. This is called magnetic capture. We investigate in detail for which…
We track the growth and evolution of high redshift seed black holes over cosmic time. This population of massive, initial black hole seeds form at these early epochs from the direct collapse of pre-galactic gas discs. Populating dark matter…
We investigate the evolution of the properties of model populations of ultraluminous X-ray sources (ULXs) consisting of a black-hole accretor in a binary with a donor star. We have computed models corresponding to three different…
The properties of X-ray emission from accreting black holes are reviewed. The contemporary observational picture and current status of theoretical understanding of accretion and formation of X-ray radiation in the vicinity of the compact…
A binary in which a slightly evolved star starts mass transfer to a neutron star can evolve towards ultra-short orbital periods under the influence of magnetic braking. This is called magnetic capture. We investigate in detail for which…
What are the most important conditions and processes governing the growth of stellar-origin compact objects? The identification of compact object type as either black hole (BH) or neutron star (NS) is fundamental to understanding their…
We investigate the joint primary mass, mass ratio, and redshift observed distribution of astrophysical black holes using the gravitational wave events detected by the LIGO-Virgo-KAGRA collaboration and included in the third gravitational…
We study the origin of the ultraluminous X-ray source M82-X1 in the nearby starburst galaxy M82. This X-ray source is of particular interest as it is currently the best candidate intermediate mass black hole; it is associated with a 54mHz…