2003•CERN Document Server (European Organization for Nuclear Research)Open access
INTEGRAL-RXTE observations of Cygnus X-1
K. Pottschmidt, J. Wilms, M. Chernyakova, M. A. Nowak, J. Rodríguez, A. A. Zdziarski, V. Beckmann, P. Kretschmar, T. Gleissner, G. G. Pooley, S. Martínez‐Núñez, T. J.-L. Courvoisier, Schoenfelder, V., R. Staubert
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Abstract
We present first results from contemporaneous observations of Cygnus X-1 with INTEGRAL and RXTE, made during INTEGRAL's 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/2pi~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.