相关论文: Hybrid Comptonization and Electron-Positron Pair P…

Hard X-ray spectra of black hole binaries in the low/hard state are well modeled by thermal Comptonization of soft seed photons by a corona-type region with $kT$\thinspace$\sim 50${\thinspace}keV and optical depth around 1. Previous…

MAXI J1820+070 is a newly discovered transient black hole X-ray binary, which showed several spectral and temporal features. In this work, we analyse the broadband X-ray spectra from all three simultaneously observing X-ray instruments…

At high luminosities black hole binaries show spectra with a strong disc component accompanied by an equally strong tail where at least some of the electrons are non-thermal. We reanalyze the simultaneous ASCA-RXTE-OSSE data from the 1998…

We present an analysis of the covariance spectrum of the black hole X-ray binary MAXI J1820+070 during its hard state. For the first time, we extend coherence and covariance studies into the hard X-ray band up to 150 keV. We detect a clear…

The 4-200 keV spectral and temporal behaviour of the low mass X-ray binary 4U 1820-30 has been studied with INTEGRAL during 2003-2005. This source as been observed in both the soft (banana) and hard (island) spectral states. A high energy…

We study X-ray and soft gamma-ray spectra from the hard state of the accreting black-hole binary MAXI J1820+070. We perform analysis of joint spectra from HXMT, NuSTAR and INTEGRAL. We find an overall agreement between the spectra from all…

We present a comprehensive multi-wavelength spectral analysis of the black hole X-ray binary MAXI J1820+070 during its 2018 outburst, utilizing AstroSat far UV, soft and hard X-ray data, along with (quasi-)simultaneous optical and X-ray…

We study the 4-200 keV spectral and temporal behaviour of the low mass X-ray binary 4U 1820-30 with INTEGRAL during 2003-2005. This source as been observed in both the soft (banana) and hard (island) spectral states. A high energy tail,…

In the inner regions of an accretion disk around a black hole, relativistic protons can interact with ambient matter to produce electrons, positrons and $\gamma$-rays. The resultant steady state electron and positron particle distributions…

We report on a \textit{NuSTAR} and \textit{Swift}/XRT observation of the newly discovered X-ray transient MAXI J1820+070. \textit{Swift}/XRT and \textit{NuSTAR} have concurrently observed the newly detected source on 14 March 2018. We have…

Aims. The black hole binary SWIFT J1753.5-0127 is providing a unique data set to study accretion flows. Various investigations of this system and of other black holes have not, however, led to an agreement on the accretion flow geometry or…

We study the structure of the accretion flow in the hard state of the black-hole X-ray binary MAXI~J1820+070 with \nicer data. The power spectra show broadband variability which can be fit with four Lorentzian components peaking at…

Black hole X-ray binaries in the quiescent state (Eddington ratios typically $\lesssim$10$^{-5}$) display softer X-ray spectra (photon indices $\Gamma\sim2$) compared to higher-luminosity black hole X-ray binaries in the hard state…

X-ray emission from AGN is believed to be produced via Comptonization of optical/UV seed photons emitted by the accretion disk, up-scattered by hot electrons in a corona surrounding the black hole. A critical compactness vs. temperature…

Based on recent multiwavelength observations of the new X-ray nova XTE J1118+480, we can place strong constraints on the geometry of the accretion flow in which a low/hard state spectrum, characteristic of an accreting black hole binary, is…

The nature of the broad-band spectra of supermassive accreting black holes in active galactic nuclei (AGNs) is still unknown. The hard X-ray spectra of Seyferts as well as of Galactic stellar-mass black holes (GBHs) are well represented by…

We consider a Compton cloud (CC) surrounding a black hole (BH) in an accreting black hole system, where electrons propagate with thermal and bulk velocities.In that cloud, soft (disk) photons may be upscattered off these energetic electrons…

The Galactic black hole X-ray binary MAXI J1820+070 had a bright outburst in 2018 when it became the second brightest X-ray source in the Sky. It was too bright for X-ray CCD instruments such as XMM-Newton and Chandra, but was well observed…

Studies of the long-term spectral variations have been used to constrain the emission processes of black hole candidates. However, a common scenario which is able to explain the emission from soft to hard X-rays has been proposed only…

Electron-positron pairs may be produced near accreting black holes by a variety of physical processes, and the resulting pair plasma may be accelerated and collimated into a relativistic jet. Here we use a self-consistent dynamical and…