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Radiation mechanisms and geometry of cygnus X-1 in the soft state
We present X-ray/γ-ray spectra of Cyg X-1 observed during the transition from the hard to the soft state and in the soft state by ASCA, RXTE and CGRO/OSSE in 1996 May and June. The spectra consist of
Supercritically accreting stellar mass black holes as ultraluminous X-ray sources
We derive the luminosity‐temperature relation for the supercritically accreting black holes (BHs) and compare it to the data on ultraluminous X-ray sources (ULXs). At super-Eddington accretion rates,
Broad-band X-ray/γ-ray spectra and binary parameters of GX 339–4 and their astrophysical implications
We present X-ray/γ-ray spectra of the binary GX 339–4 observed in the hard state simultaneously by Ginga  and CGRO  OSSE during an outburst in 1991 September. The Ginga  X-ray spectra are well
The Two-Phase Pair Corona Model for Active Galactic Nuclei and X-ray Binaries: How to Obtain Exact Solutions
We consider two phase accretion disk-corona models for active galactic nuclei and some X-ray binaries. We describe in detail how one can exactly solve the polarized radiative transfer and
Spectra of the brightest blazars detected by the Fermi Gamma-ray Space Telescope Large Area Telescope cannot be described by a simple power-law model. A much better description is obtained with a
The Soft Gamma-Ray Spectral Variability of Cygnus X-1
We have used observations of Cyg X-1 from the Compton Gamma Ray Observatory and BeppoSAX to study the variation in the MeV γ-ray emission between the hard and soft spectral states, using spectra that
Understanding the Long-Term Spectral Variability of Cygnus X-1 with Burst and Transient Source Experiment and All-Sky Monitor Observations
We present a comprehensive analysis of all observations of Cyg X-1 by the Compton Gamma Ray Observatory Burst and Transient Source Experiment (BATSE; 20-300 keV) and by the Rossi X-Ray Timing
Spectral variability of ultraluminous X-ray sources
We study spectral variability of 11 ultraluminous X-ray sources (ULX) using archived XMM-Newton and Chandra observations. We use three models to describe the observed spectra: a power law, a
Limits to dark matter annihilation cross-section from a combined analysis of MAGIC and Fermi-LAT observations of dwarf satellite galaxies
We present the first joint analysis of gamma-ray data from the MAGIC Cherenkov telescopes and the Fermi Large Area Telescope (LAT) to search for gamma-ray signals from dark matter annihilation in
Observations of Seyfert Galaxies by OSSE and Parameters of Their X-Ray/Gamma-Ray Sources
We present a summary of spectra of Seyfert galaxies observed by the OSSE detector aboard Compton Gamma Ray Observatory. We obtain average spectra of Seyfert galaxies of types 1 and 2 and find they