Related papers: Obscuration effects in Super-Soft-Source X-ray spe…
A Chandra ACIS-S imaging observation of the nearby galaxy M81 (NGC 3031) reveals 9 luminous soft X-ray sources. The local environments, X-ray spectral properties, and X-ray light curves of the sources are presented and discussed in the…
We analyze a large collection of RXTE archive data from April 1997 to August 2003 of the bright X-ray source Scorpius X-1 in order to study the broadband spectral evolution of the source for different values of the inferred mass accretion…
X-ray binaries, as bright local sources with short variability timescales for a wide range of accretion processes, represent ideal targets for high-resolution X-ray spectroscopy. In this chapter, we present a high-resolution X-ray spectral…
X-ray absorption and emission lines now serve as powerful diagnostics of the outflows from active galaxies. Detailed X-ray line studies of outflows have recently been enabled for a significant number of active galaxies via the grating…
The transient ULX in M83 that went into outburst in or shortly before 2010 is still active. Our new XMM-Newton spectra show that it has a curved spectrum typical of the upper end of the high/soft state or slim-disk state. It appears to be…
We have analyzed archival Ginga data of a number of Soft X-ray Transient sources and modelled them in an attempt to constrain the geometry and physical properties of accretion. Our models include a self-consistent description of X-ray…
ASCA X-ray spectra of many ULXs were described in terms of optically thick emission from hot (kT ~1-2keV) accretion disks, while recent XMM-Newton and Chandra observations have revealed a cool (kT ~0.2keV), soft X-ray excess emission from a…
We present new interpretation of Ton S180 spectrum obtained by {\it Chandra} Spectrometer (Low Energy Transmission Grating). Several narrow absorption lines and a few emission disk lines have been successfully fitted to the data. We have…
Over the last 3 yrs, the Galactic center (GC) region has been monitored with the Chandra X-Ray Observatory. With 11 Chandra observations through 2002 June, the total effective exposure reaches ~590 ks, providing significant photon…
Understanding how black holes accrete and supply feedback to their environment is one of the outstanding challenges of modern astrophysics. Swift J1910.2-0546 is a candidate black hole low-mass X-ray binary that was discovered in 2012 when…
Recent time-resolved X-ray spectra of a neutron star undergoing a superburst revealed an Fe K line and edge consistent with reprocessing from the surrounding accretion disc. Here, we present models of X-ray reflection from a constant…
Moderate-resolution, near-infrared spectra between 0.8 and 5.2 microns were obtained for 12 late-type (K0-M3) disk-bearing members of the ~5 Myr old Upper Scorpius OB association using SpeX on the NASA Infrared Telescope Facility. For most…
The propeller effect should cut off accretion in fast-spinning neutron star high mass X-ray binaries (HMXBs) at low mass transfer rates. However, accretion continues in some HMXBs at $L_{x} < 10^{34}$ erg s$^{-1}$, as evidenced by…
We present the X-ray spectra of 86 optically-identified sources in the 13H XMM-Newton/Chandra deep field which have >70 X-ray counts. The sample consists of 50 broad line AGN, 25 narrow emission line galaxies, 6 absorption line galaxies,…
The nearby barred spiral galaxy NGC 1313 has been observed with the PSPC instr- ument on board the ROSAT X-ray satellite. Ten individual sources are found. Three sources (X-1, X-2 and X-3 [SN~1978K]) are very bright (~10^40 erg/s) and are…
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…
Slim disks have been received much attention because of the increasing evidence for the super-critical accreting objects. In this paper, we make an attempt to construct a unified model, in which the viscosity and the dimensionless accretion…
Most of the super-massive black holes in the Universe accrete material in an obscured phase. While it is commonly accepted that the "dusty torus" is responsible for the nuclear obscuration, its geometrical, physical, and chemical properties…
Supercritical accretion onto compact objects powers a massive wind that is optically thick and Eddington-limited. If most of the hard X-rays from the central disk are obscured by the wind, the source will display a blackbody-like spectrum…
Hard X- and $\gamma$-ray spectra and light curves resulting from radioactive decays are computed for aspherical (jet-like) and energetic supernova models (representing a prototypical hypernova SN 1998bw), using a 3D energy- and…