Evidence of variation of the accretion flow geometry in GRS 1915+105   from IXAE and RXTE data
  The Galactic microquasar GRS 1915+105 exhibits various types of light curves. There is, however, no understanding of when a certain type of light curve will be exhibited and only in a handful of cases, the transitions from one type to another have actually been observed. We study the detailed spectral properties in these cases to show that that different classes have different ratio of the power-law photon and the blackbody photon. Since the power-law photons are from the Compton cloud, and the intensity of the power-law photon component depends on the degree of interception of the soft photons by the Compton cloud, we conclude that not only the accretion rate, but the accretion flow geometry must also change during a class transition. 
Partha Sarathi Pal, Sandip K. Chakrabarti and Anuj Nandi
astro-ph.HE