Thermal Comptonization in GRS 1915+105

Abstract

The Rossi X-ray Timing Explorer data of GRS 1915+105 from several observing periods are modeled with a thermal Comptonization model. Best-fit models indicate that there is a strong correlation between the inner disk temperature and the disk luminosity. The hard Comptonized luminosity does not depend significantly on the total luminosity. The spectral hardness of the Comptonized radiation, the fraction of seed soft photons scattered by the Comptonizing cloud, its Thomson optical depth, and the fraction of the total power dissipated in the optically thin hot plasma, all strongly anticorrelate with the luminosity. We find that the inner disk radius is almost constant and that the hot Comptonizing corona shrinks at high luminosities. We note that the fits using xspec diskbb + power law model underestimate the amplitude of the blackbody component (and therefore the corresponding size of the emitting region) and overestimate the absorption column density and the total, corrected for absorption, luminosity.

4 pages in emulateapj5.sty, 3 figures. Substantially revised version accepted for publication in ApJ Letters

References in corpus (2)

• Radiation mechanisms and geometry of Cygnus X-1 in the soft state
• The Formation and Structure of a Strongly Magnetized Corona above Weakly Magnetized Accretion Disks

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• First INTEGRAL observations of GRS 1915+105
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• Spectral modeling of the three spectral states of the Galactic microquasar GRS 1915+105
• Mass transfer from the donor of GRS 1915+105
• GRS 1915+105 : High-energy Insights with SPI/INTEGRAL