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Session 44 - Double Stars.
Display session, Thursday, January 08
Exhibit Hall,

[44.01] Time Resolved Spectra and QPO Tracking of Microquasar GRS 1915+105

M. P. Muno, E. H. Morgan, R. A. Remillard, H. V. D. Bradt (M.I.T. Center for Space Research)

GRS 1915+105 is one of two known microquasars, galactic objects that have been associated with relativistic jets and intense radio, infrared, and x-ray emission. Both sources are thought to be a binary system containing a black hole that is accreting matter from a stellar companion. GRS 1915+105 has been observed almost weekly with the Proportional Counter Array (PCA) of the Rossi X-ray Timing Explorer during the past year. We used 129 channel (2--60keV) data accumulated over 16 second intervals to model the energy spectrum, and data with a time resolution of 125 \mus to produce power dentisy spectra for the same time intervals. We compared a simple model consisting of a thermal multi-temperature blackbody and a non-thermal power law with the energy spectrum for each time interval through a least-squares minimization technique. We thus obtained estimates for the temperature and inner radius of the accretion disk. We then tracked a quasi-periodic oscillation (QPO) in the the power density spectra, which was observed to vary between 3--10 Hz, positively correlated with the flux. Finally, we examined correlations between the various energy spectral parameters and the QPO frequency to model the interaction of the accretion disk with the central black hole.

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