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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 τ ∼ 1.0−1.3 plus reflection from a cold or mildly ionized slab with a covering factor of Ω/2π ∼ 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. |
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POTTSCHMIDT, K. ; Wilms, J. ; Chernyakova, M. ; Nowak, M.A. ; Rodriguez, J. ; Zdziarski, A.A. ; Beckmann, V. ; Kretschmar, P. ; Gleissner, T. ; Pooley, G.G. ; Martinez Nuñez, Silvia ; Courvoisier, T.J.L. ; Schönfelder, V. ; Staubert, R., 2003, INTEGRAL-RXTE observations of Cygnus X-1, Astronomy and Astrophysics, vol. 411, no. 1, p. L383–L388 |
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