Related papers: Powerful, Rotating Disk Winds from Stellar-mass Bl…
We present the results of the uniform analysis of 46 XMM-Newton observations of six BAL and seven mini-BAL QSOs belonging to the Palomar-Green Quasar catalogue. Moderate-quality X-ray spectroscopy was performed with the EPIC-pn, and allowed…
We discuss the observational consequences of black hole spin in X-ray binaries within the framework of the standard thin accretion disk model. When compared to theoretical flux distribution from the surface of a thin disk surrounding a Kerr…
We present simultaneous Chandra-HETG and RXTE observations of a moderate flux `soft state' of the black hole candidate 4U1957+11. These spectra, having a minimally discernible hard X-ray excess, are an excellent test of modern disk…
In astronomy, the problem of black holes is arguably second in importance only to the problem of cosmology. A current frontier in black hole research is the measurement of spin. During the past three years, the spins of several stellar-mass…
The fluorescent iron K$\alpha$ emission line profile provides an excellent probe of the innermost regions of active galactic nuclei. Fe XXV and Fe XXVI in diffuse plasma above the accretion disc can affect the X-ray spectrum by iron…
An extended XMM-Newton observation of the Seyfert 1 galaxy NGC 4051 in 2009 detected a photo-ionized outflow with a complex absorption line velocity structure and a broad correlation of velocity with ionization parameter, shown in Pounds et…
Most black holes (BHs) formed in collapsing stars have low spin, though some are expected to acquire a magnetic accretion disk during the collapse. While such BH disks can launch magnetically driven winds, their physics and observational…
We have considered the existence of neutron star magnetic field given by the cyclotron lines. We collected the data of 9 sources of high-mass X-ray binaries with supergiant companions as a case of testing our model, to demonstrate their…
The compact X-ray source in the eclipsing X-ray binary IC 10 X-1 has reigned for years as ostensibly the most massive stellar-mass black hole, with a mass estimated to be about twice that of its closest rival. However, striking results…
MAXI J1348-630 is a low mass X-ray binary discovered in 2019 during a bright outburst. During this event, the system sampled both hard and soft states following the standard evolution. We present multi-epoch optical and near-infrared…
We report on XRISM/Resolve spectroscopy of the recurrent transient and well-known black hole candidate 4U 1630$-$472 during its 2024 outburst. The source was captured at the end of a disk-dominated high/soft state, at an Eddington fraction…
Past X-ray observations of the nearby luminous quasar PDS 456 (at $z=0.184$) have revealed a wide angle accretion disk wind (Nardini et al. 2015), with an outflow velocity of $\sim-0.25c$. Here we unveil a new, relativistic component of the…
We study reflected X-ray emission that returns to the accretion disc in the strong gravitational fields around black holes using General Relativistic ray tracing and radiative transfer calculations. Reflected X-rays that are produced when…
We present the results from simultaneous Chandra HETGS and RXTE observations of the microquasar GRS 1915+105 in its quasi-stable "soft state" (or State A) performed on 2007 August 14, several days after the state transition from "hard…
Context: Cygnus X-1 is a black hole X-ray binary system in which the black hole captures and accretes gas from the strong stellar wind emitted by its supergiant O9.7 companion star. The irradiation of the supergiant star essentially…
Accretion disk winds are thought to produce many of the characteristic features seen in the spectra of active galactic nuclei (AGN) and quasi-stellar objects (QSOs). These outflows also represent a natural form of feedback between the…
By performing two-dimensional axisymmetric general relativistic radiation magnetohydrodynamics simulations with spin parameter $a^*$ varying from -0.9 to 0.9, we investigate the dependence on the black hole spin of the energy flow from…
The class of B[e] supergiants is characterized by a two-component stellar wind consisting of a normal hot star wind in the polar zone and a slow and dense disk-like wind in the equatorial region. The properties of the disk wind are…
We show that the continuum X-ray spectrum of 4U 1630-472 with iron absorption lines can be satisfactorily modeled by the spectrum from an accretion disk atmosphere. We performed full radiative transfer calculations using our code ATM21 to…
Fast, massive winds are ubiquitously observed in the UV and X-ray spectra of Active Galactic Nuclei (AGN) and other accreting sources. Theoretical and observational evidences suggest they are launched at accretion disc scales, carrying…