[Previous] | [Session 83] | [Next]
C.R. Shrader (NASA/GSFC, USRA), L.G. Titarchuk (NASA/GSFC, NRL, GMU)
We discuss some emerging empirical trends spectral-temporal behavior of Galactic accreting black holes, such as the luminosity and spectral dependence of QPO phenomena, hard and phase soft lags and the lack of coherence between hard- and soft-band variability. We offer interpretation of these trends in the context of a viscous, thermal accretion disk and Comptonization from a relativistic bulk inflow. We find that we are able to explain some of these trends, such as the positive correlation between power and energy for the ~102-Hz QPOs, in a natural manner. Similarly, the decrease in hard-soft coherence observed in low- to high-state transitions is a natural consequence of the compact origin we propose for the hard photons. We present examples from recent X- and gamma-ray observations made with the Compton Gamma Ray Observatory and the Rossi X-Ray Timing Explorer to substantiate these ideas, and comment on the prospects for achieving further progress with the forthcoming Instrumentation such as those onboard INTEGRAL.
The author(s) of this abstract have provided an email address for comments about the abstract: shrader@grossc.gsfc.nasa.gov