Related papers: Thick Accretion Disk Model for Ultraluminous Super…
To what extent can the one-dimensional slim disk model reproduce the multi-dimensional results of global radiation-hydrodynamic simulations of super-Eddington accretion? With this question in mind, we perform systematic simulation study of…
Data from {\it Chandra} observations of thirty nearby galaxies were analyzed and 365 X-ray point sources were chosen whose spectra were not contaminated by excessive diffuse emission and not affected by photon pile up. The spectra of these…
We consider supercritical accretion onto a compact object when the accretion rate exceeds its value derived from the Eddington limit: L_{Edd}/c^2. We use the scenario that was proposed by Shakura and Sunyaev (1973) for the supercritical…
We investigate the dependence of the viewing angle in supercritical accretion flows and discuss the observational implications of galactic black-hole candidates and ultraluminous X-ray sources. When the mass accretion rate exceeds the…
There are two proposed explanations for ultraluminous X-ray sources (ULXs) with luminosities in excess of $10^{39}$ erg s$^{-1}$. They could be intermediate-mass black holes (more than 100-1,000, solar masses, $M_\odot$) radiating at…
X-ray reverberation has proven to be a powerful tool capable of probing the innermost region of accretion disks around compact objects. Current theoretical effort generally assumes that the disk is geometrically thin, optically thick and…
Although we are nearing a consensus that most ULXs are stellar-mass black holes in a super-Eddington state, little is yet established of the physics of this accretion mode. Here, we use a combined X-ray spectral and timing analysis of a…
It is thought that ultraluminous X-ray sources (ULXs) are mainly powered by super-Eddington accreting neutron stars or black holes as shown by recent discovery of X-ray pulsations and relativistic winds. This work presents a follow up study…
We present a comprehensive analysis of four near-Eddington black hole accretion models computed by solving the GRMHD equations with full radiation transport. This study focuses on the dynamical effects of magnetic field topology and black…
We perform non-hydrodynamical 2.5D simulations to study the dynamics of material above accretion disk based on the disk radiation pressure acting on dust. We assume a super-accreting underlying disk with the accretion rate of 10 times the…
Aims. We analyzed multi-epoch X-ray data of the Ultraluminous X-ray source (ULX) NGC 5055 X-1, with luminosity up to $2.32\times10^{40}\ \rm erg\ s^{-1}$, in order to constrain the physical parameters of the source. Methods. We performed…
We have chosen 6 Ultra-Luminous X-ray sources from the {\it XMM-Newton} archive whose spectra have high signal-to-noise and can be fitted solely with a disk model without requiring any power-law component. To estimate systematic errors in…
Some ultraluminous X-ray sources in nearby galaxies show soft components resembling thermal disc emission. Calculations based on blackbody emission then indicate that the accreting black holes at the centres of these discs have masses of…
In this letter, we comment on the robustness of putative cool (kT ~ 0.2 keV) accretion disc components in the X-ray spectra of the most luminous (L ~ 10^40 erg/s) ultra-luminous X-ray sources (ULXs) in nearby normal galaxies. When compared…
Standard accretion disc model relies upon several assumptions, the most important of which is geometrical thinness. Whenever this condition is violated, new physical effects become important such as radial energy advection and mass loss…
We use global three dimensional radiation magneto-hydrodynamic simulations to study the properties of inner regions of accretion disks around a 5\times 10^8 solar mass black hole with mass accretion rates reaching 7% and 20% of the…
We present a detailed model of an extreme slim disk (ESD) with a hot corona around a massive black hole with dimensionless accretion rate $\dotm$ in the range $2.5\ll \dotm\leq 100$. We assume that a fraction $f$ of the gravitational energy…
We have analyzed an XMM-Newton observation of the nearby spiral galaxy NGC 1313, which contains two "ultra-luminous" X-ray (ULX) sources. We measure isotropic luminosities of L_X = 2.0 * 10^(40) erg/s and L_X = 6.6 * 10^(39) erg/s for NGC…
The luminosities of ultraluminous X-ray sources (ULXs) require an exotic solution with either super-critical accretion modes onto stellar mass black holes or sub-critical accretion onto intermediate mass black holes (IMBHs) being invoked.…
Numerical general relativistic radiative magnetohydrodynamic simulations of accretion disks around a stellar mass black hole with a luminosity above 0.5 of the Eddington value reveal their stratified, elevated vertical structure. We refer…