Related papers: Radiation Feedback in Hot Accretion-Disk Corona Mo…
The dramatic hard-soft spectral transition in Black Hole Binaries is important as it is associated with the collapse of the jet and with the strongest low frequency QPOs. These transition spectra (intermediate and very high state: VHS) are…
Black-hole X-ray binaries (BHXRBs) in the hard and hard-intermediate spectral (and temporal) states exhibit in their power spectra characteristic frequencies called type-C quasi-periodic oscillations (QPOs). Various models that can explain…
Reflection of X-rays from cool material around a black hole is one of the few observational diagnostics of the accretion flow geometry. Models of this reflected spectrum generally assume that the accretion disk can be characterized by…
The high-energy emission ($400$ keV $- 2$ MeV) of Cygnus X-1 --the most well-studied Galactic black hole-- was recently found to be strongly polarized. The origin of this radiation is still unknown. In this work, we suggest that it is the…
Most of the luminosity of accreting black hole is emitted in the X-ray band. This radiation is believed to emerge, through inverse Compton process, from a hot (Te ~ 10^8 -10^9 K) optically thin (Thomson optical depth ~ 1) plasma probably…
Radiation pressure dominated accretion discs may have turbulent velocities that exceed the electron thermal velocities. Bulk Comptonization by the turbulence may therefore dominate over thermal Comptonization in determining the emergent…
We construct a simple model for a magnetic reconnection heated corona above a thin accretion disk in AGNs and Galactic black hole candidates(GBHCs). The basic assumptions are that (1) the magnetic reconnection heat is cooled down…
We apply our self-consistent accretion disk corona (ADC) model, with two different geometries, to the broad-band X-ray spectrum of the black hole candidate Cygnus X-1. As shown in a companion paper (Dove, Wilms, and Begelman), models where…
We present calculations of non-LTE, relativistic accretion disk models applicable to the high/soft state of black hole X-ray binaries. We include the effects of thermal Comptonization and bound-free and free-free opacities of all abundant…
Relativistic reflection features in the X-ray spectra of accreting black holes are considered to be generated by the illumination of the accretion disk by the hot corona. In this work, we present a numerical method for the emission line…
Most of the spectra of neutron star low mass X-ray binaries (NS LMXBs), being them persistent or transient, are characterized by the presence of a strong thermal Comptonization bump, thought to originate in the transition layer (TL) between…
X-ray reverberation in AGN, believed to be the result of the reprocessing of corona photons by the underlying accretion disk, has allowed us to probe the properties of the inner-most regions of the accretion flow and the central black hole.…
The inverse Compton process by which soft photons are up-scattered by hot electrons in a corona plays a fundamental role in shaping the X-ray spectra of black-hole (BH) low-mass X-ray binaries (LMXBs), particularly in the hard and…
We develop a new theoretical model describing the formation of the radiation spectrum in accretion-powered X-ray pulsars as a result of bulk and thermal Comptonization of photons in the accretion column. The new model extends the previous…
We present a broadband spectral analysis of the black hole X-ray binary GX 339-4 during its 2021 outburst, covering both hard and soft spectral states. Using simultaneous observations from NuSTAR, NICER, and Insight-HXMT, we investigate the…
Recently, much attention has been paid to the magnetic coupling (MC) process, which is supported by very high emissivity indexes observed in Seyfert 1 galaxy MCG-6-30-15 and GBHC XTE J1650-500. But the rotational energy transferred from a…
Active galactic nuclei host an accretion disc with an X-ray producing corona around a supermassive black hole. In bright sources, such as the Seyfert 1 galaxy Mrk 335, reflection of the coronal emission off the accretion disc has been…
A new mechanism to form a magnetic pressure supported, high temperature corona above the photosphere of an accretion disk is explored using three dimensional radiation magneto-hydrodynamic (MHD) simulations. The thermal properties of the…
We discuss a model for the central region of radio-quiet AGN in which coronal accretion is the source of energy for X-ray emission. We start from the Haardt & Maraschi model but supplement it with pressure balance condition, two…
We develop a two-flow model of accretion onto a black hole which incorporates the effect of the local magneto-rotational instability. The flow consists of an accretion disk and an accreting corona, and the local dynamo affects the…