Related papers: X-ray Fluctuations from the Slim Disk
When a star is torn apart by the tidal forces of a supermassive black hole (a so-called TDE) a transient accretion episode is initiated and a hot, often X-ray bright, accretion disk is formed. Like any accretion flow this disk is turbulent,…
(abridged) We review how the recent increase in X-ray and radio data from black hole and neutron star binaries can be merged together with theoretical advances to give a coherent picture of the physics of the accretion flow in strong…
Many statistical properties of X-ray aperiodic variability from accreting compact objects can be explained by the propagating fluctuations model applied to the accretion disc. The mass accretion rate fluctuations originate from variability…
A thermal soft X-ray component is often detected in low-level accreting neutron stars (NSs), but is not detected in low-level accreting stellar-mass black holes (BHs). In this paper, we investigate the origin of such a thermal soft X-ray…
Active galactic nuclei (AGN) have been observed to vary stochastically with 10-20 rms amplitudes over a range of optical wavelengths where the emission arises in an accretion disk. Since the accretion disk is unlikely to vary coherently,…
In this Letter we investigate the properties of advection-dominated accretion flows (ADAFs) fed by the evaporation of a Shakura-Sunyaev accretion disk (SSD). In our picture the ADAF fills the central cavity evacuated by the SSD and extends…
We investigate the structure of accretion disks around massive protostar applying steady state models of thin disks. The thin disk equations are solved with proper opacities for dust and gas taking into account the huge temperature…
This paper aims to investigate/map the effects that perturbations applied to an accretion disk might produce on the registered Light Curves (LC). The case of accretion disks around supermassive active black holes (AGNs) is studied with the…
Cold optically thick accretion disks with hot coronae and radial advection have been investigated. Within the framework of $\alpha$-viscosity models, we assume that all the mass accretion and angular momentum transport take place in the…
XMM-Newton X-ray spectra of the hard state Black Hole X-Ray Binaries (BHXRBs) SWIFT J1753.5-0127 and GX 339-4 show evidence for accretion disc blackbody emission, in addition to hard power-laws. The soft and hard band Power-Spectral…
The UV emission from X-ray binaries, is more likely to be produced by reprocessing of X-rays by the outer regions of an accretion disk. The structure of the outer disk may be altered due to the presence of X-ray irradiation and we discuss…
We analyze X-ray light curves of the blazar Mrk 421 obtained from the Soft X-ray Imaging Telescope and the Large Area X-Ray Proportional Counter instrument onboard the Indian space telescope $AstroSat$ and archival observations from…
Radiation pressure-dominated accretion disks are predicted to exhibit strong density inhomogeneities on scales much smaller than the disk scale height, due to the nonlinear development of photon bubble instability. Radiation would escape…
Soft and hard spectral states of X-ray transient sources reflect two modes of accretion, accretion via a geometrically thin, optically thick disk or an advection-dominated accretion flow (ADAF). The luminosity at transition between these…
In the canonical understanding of transient X-ray sources the accretion during quiescence occurs via a geometrically thin disk in the outer part and via an advection-dominated hot coronal flow/ADAF in the inner part. The inner part…
In this chapter, we review some of the interesting consequences that tilt between the spin axis of the black hole and angular momentum axis of the accretion disk can have on the dynamics, thermodynamics, and observational appearance of…
Planets embedded in optically thick passive accretion disks are expected to produce perturbations in the density and temperature structure of the disk. We calculate the magnitudes of these perturbations for a range of planet masses and…
The X-ray spectrum from a cool accretion disk heated by virialized protons is computed. The cool disk is either embedded in a magnetically heated accretion disk corona or partly extends into an ion supported torus (or ADAF). We calculate…
We construct a numerical model of steady-state, general relativistic (GR) super-Eddington accretion flows in an optically thick, advection-dominated regime, motivated by tidal disruption events wherein super-Eddington accretion assumes a…
At super-Eddington rates accretion flows onto black holes have been described as slim (aspect ratio $H/R \lesssim 1$) or thick (H/R >1) discs, also known as tori or (Polish) doughnuts. The relation between the two descriptions has never…