RXTE Observations of Cygnus X-1: Broad-Band Spectra and High-Resolution   Timing
  We present results from a 20 ksec RXTE observation of the black hole candidate Cyg X-1. We apply self-consistent accretion disk corona models to these hard state data and show that Comptonization in a spherical corona irradiated by soft photons from an exterior cold disk is able to successfully model the spectrum. We also present the power spectrum, the coherence function, and the time lags for lightcurves from four energy bands. By modeling the high-resolution lightcurves with stochastic linear state space models, we show that the rapid hard state variability of Cyg X-1 can be explained with a single timescale. 
K. Pottschmidt (1), J. Wilms (1), M. A. Nowak (2), J. B. Dove (3), M.   C. Begelman (2), R. Staubert (1) ((1) Institute for ...