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Radiation mechanisms and geometry of cygnus X-1 in the soft state
- M. Gierliński, A. Zdziarski, J. Poutanen, P. Coppi, K. Ebisawa, W. Johnson
- Physics
- 12 May 1999
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
- J. Poutanen, G. Lipunova, S. Fabrika, A. Butkevich, P. Abolmasov
- Physics
- 11 September 2006
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
- A. Zdziarski, J. Poutanen, J. Mikołajewska, M. Gierliński, K. Ebisawa, W. Johnson
- Physics
- 29 July 1998
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
- J. Poutanen, R. Svensson
- Physics
- 14 May 1996
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…
GeV BREAKS IN BLAZARS AS A RESULT OF GAMMA-RAY ABSORPTION WITHIN THE BROAD-LINE REGION
- J. Poutanen, B. Stern
- Physics
- 20 May 2010
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
- M. McConnell, A. Zdziarski, +11 authors A. Strong
- Physics
- 13 December 2001
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
- A. Zdziarski, J. Poutanen, W. Paciesas, L. Wen
- Physics
- 10 October 2002
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
- J. Kajava, J. Poutanen
- Physics
- 8 June 2009
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
- M. L. Ahnen, S. Ansoldi, +154 authors L. Strigari
- Physics
- 25 January 2016
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
- A. Zdziarski, J. Poutanen, W. Johnson
- Physics
- 11 June 2000
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…
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