Author/Authors :
Rodriguez، J. نويسنده , , Pottschmidt، K. نويسنده , , Pooley، G. G. نويسنده , , Zdziarski، A. A. نويسنده , , Kretschmar، P. نويسنده , , Staubert، R. نويسنده , , Courvoisier، T. J.-L. نويسنده , , Wilms، J. نويسنده , , Nowak، M. A. نويسنده , , Gleissner، T. نويسنده , , Schonfelder، V. نويسنده , , Beckmann، V. نويسنده , , Chernyakova، M. نويسنده , , Martinez-Nunez، S. نويسنده ,
Abstract :
We present first results from contemporaneous observations of Cygnus X-1 with INTEGRAL and RXTE, made during INTEGRALʹs performance verification phase in 2002 November and December. Consistent with earlier results, the 3-250 keV data are well described by Comptonization spectra from a Compton corona with a temperature of kT~50-90 keV and an optical depth of (tau)~1.0-1.3 plus reflection from a cold or mildly ionized slab with a covering factor of (omega)/2(pi) ~0.2-0.3. A soft excess below 10 keV, interpreted as emission from the accretion disk, is seen to decrease during the 1.5 months spanned by our observations. Our results indicate a remarkable consistency among the independently calibrated detectors, with the remaining issues being mainly related to the flux calibration of INTEGRAL.
Keywords :
X-rays: general , black hole physics , stars: individual: Cyg X-1 , gamma rays: observations , X-rays: binaries
