We present results from a timing analysis of Cygnus X-1 data taken with RXTE during December 1997 when the source was in its hard state. We present cross correlation functions, autocorrelation functions, and conditional densities (used to test for fractal structure) across a wide range of spectral bands down to millisecond timescales to find maximum and minimum variability timescales. We note that while the cross-correlation functions over a wide range of energies are asymmetric, they are all peaked at lags of less than 5 milliseconds. We compare the observed variability as a function of energy with the predictions of various flare models for Cygnus X-1, in particular those which involve large, inhomogeneous Comptonizing clouds.
AAS/High Energy Astrophysics Division #4
- Pub Date:
- April 1999