37th Scientific Assembly of the Committee on Space Research
Montreal, Canada
2008 July 13–20

Joint X-ray observations of Cygnus X-1 at orbital phase zero

K. Pottschmidt, M. Hanke, J. Wilms, M. A. Nowak, N. S. Schulz, J. C. Lee, I. Kreykenbohm, L. Barragán, F. Fürst, M. Böck, S. Pirner

ADS We present first results of simultaneous observations of the high mass X-ray binary Cygnus X-1 for 50 ks with XMM-Newton, Chandra-HETGS, RXTE, Suzaku, INTEGRAL, and Swift in 2008 April. The observations are performed close to phase 0 of the 5.6 d orbit when pronounced dips in the X-ray emission from the black hole are known to occur. The dips are due to highly variable absorption in the focused wind from the O-star companion to the black hole. Compared to previous high resolution spectroscopy studies of the dip and non-dip emission with Chandraa the addition of XMM EPIC-pn and Suzaku-XIS data allows for a better determination of the continuum through the broad iron line region, while RXTE and INTEGRAL constrain the >10 keV continuum.

a Hanke, Wilms, Nowak, Pottschmidt, Schulz, & Lee (2008), ApJ [submitted]; Hanke, Wilms, Nowak, Pottschmidt, Schulz, & Lee [in preparation]

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