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Session 12 - Binary Stars.
Display session, Monday, June 08
Atlas Ballroom,

[12.01] QPOs and Spectral States in GRS 1915+105

M. P. Muno, E. H. Morgan, R. A. Remillard (Center For Space Research, MIT)

GRS 1915+105 is a microquasar, a galactic object that has been associated with relativistic jets and extremely variable radio, infrared, and x-ray emission. It is thought to be a binary system containing a black hole that is accreting matter from a stellar companion. GRS 1915+105 has been observed extensively by the Rossi X-ray Timing Explorer, and we present some results from continuing analysis of energy spectra and quasi-periodic oscillations (QPOs) in the x-ray band. We analyzed 129 channel (2--60keV) data from using a simple model consisting of a thermal multi-temperature blackbody and a non-thermal power law. We also produced power density spectra from data with a time resolution of 125 \mus and no energy resolution for coincident time intervals. We found that we can reduce the behavior of GRS 1915+105 to two distinct spectral spectral states: one state in which a QPO is present between 0.5--10 Hz and variability in the source is dominated by the power law component, and a second state in which the QPO is absent and the changes in the black body dominate the luminosity. We discuss these results in terms of ongoing efforts to explain the origin of the high energy (>10keV) emission from black hole binaries and the mechanism for the creation of relativistic jets.

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