Related papers: Obscuration effects in Super-Soft-Source X-ray spe…
We present a spectral analysis of the black hole candidate and X-ray transient source Swift J1753.5 0127 making use of simultaneous observations of XMM-Newton and Rossi X-ray Timing Explorer (RXTE) in 2006, when the source was in outburst.…
X-ray observations of Seyfert 1 galaxies offer the unique possibility of observing spectral variability on timescales comparable to the dynamical time of the inner accretion flow. They typically show highly variable lightcurves, with Power…
XMM-Newton observations of seven QSOs are presented and the EPIC spectra analysed. Five of the AGN show evidence for Fe K-alpha emission, with three being slightly better fitted by lines of finite width; at the 99 per cent level they are…
Close to a black hole, the density of the sub-Keplerian accreting matter becomes higher compared to a spherical flow due to the presence of a centrifugal barrier independent of whether or not a standing shock actually forms. This hot dense…
We present here the results of an investigation of the pulse averaged and pulse phase resolved energy spectra of two high luminosity accretion powered X-ray pulsars SMC X-1 and LMC X-4 made with ASCA. The phase averaged energy spectra…
We apply a reflection-based model to the best available XMM-Newton spectra of X-ray bright UltraLuminous X-ray (ULX) sources (NGC 1313 X-1, NGC 1313 X-2, M 81 X-6, Holmberg IX X-1, NGC 5408 X-1 and Holmberg II X-1). A spectral drop is…
We present high-resolution optical spectroscopy of the X-ray binary system SS433, obtained over a wide range of orbital phases. The spectra display numerous weak absorption features, and include the clearest example seen to date of those…
Observed spectra of Active Galactic Nuclei (AGN) and luminous X-ray binaries in our Galaxy suggest that both hot (~10^9 K) and cold (~10^6 K) plasma components exist close to the central accreting black hole. Hard X-ray component of the…
High resolution X-ray spectroscopy has revealed soft X-rays from high density plasma in Classical T-Tauri stars (CTTSs), probably arising from the accretion shock region. However, the mass accretion rates derived from the X-ray observations…
Time-resolved eclipse spectroscopy of the nova-like variable UX UMa obtained with the HST/FOS on 1994 August and November is analyzed with eclipse mapping techniques to produce spatially resolved spectra of its accretion disc and gas stream…
For small values of the dimensionless viscosity parameter, namely $\alpha\lesssim 0.1$, the dynamics of non-radiating accretion flows is dominated by convection; convection strongly suppresses the accretion of matter onto the central object…
We present a detailed analysis of broad band X-ray data of the Seyfert 2 galaxy NGC5506. 2-10 keV band are detected during a 1-day ASCA observation, while no significant change in the 2-10 keV continuum shape is found. The ASCA spectrum…
Hard X-rays above 10 keV are detected from several anomalous X-ray pulsars (AXPs) and soft gamma-ray repeaters (SGRs), and different models have been proposed to explain the physical origin within the frame of either magnetar model or…
We present detailed broadband X-ray spectral variability of a Seyfert 1 galaxy 1H~0419--577 based on an archival \suzaku{} observation in July 2007, a new \suzaku{} observation performed in January 2010 and the two latest \xmm{}…
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…
Scorpius X-1 is the brightest and first discovered X-ray source in the sky. Studying this source in the low-energy band has been challenging in the past due to its high brightness. However, with the X-ray SPECtroscopy and Timing (XSPECT)…
Detailed analysis of the lightcurve of CAL 87 clearly has shown that the high optical luminosity comes from the accretion disc rim and can only be explained by a severe thickening of the disc rim near the location where the accretion stream…
Black hole X-ray binaries show signs of non-thermal emission in the optical/near-infrared range. We analyze the optical/near-infrared SMARTS data on GX339$-$4 over the 2002--2011 period. Using the soft state data, we estimate the…
Swift observed the SSS phase in RS Oph much fainter in 2021 than in 2006, and we compare an XMM-Newton grating spectrum on day 55.6 in 2021 (2021d55.6) to SSS Chandra and XMM-Newton grating spectra from days 2006d39.7, 2006d54, and…
To understand the origin of hard X-ray emissions from black hole X-ray binaries during their low/hard states, we calculate the X-ray spectra of black-hole accretion flow for the following three configurations of hot and cool media: (a) an…