AAS 201st Meeting, January, 2003
Session 15. Black Holes Observed and Modeled
Poster, Monday, January 6, 2003, 9:20am-6:30pm, Exhibit Hall AB

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[15.12] Black Hole Masses in Narrow-Line Seyfert-1 Galaxies and Ultra-Luminous non-Nuclear X-ray Sources

C.R. Shrader (NASA/GSFC & USRA), L. Titarchuk (GMU & NRL)

The recent discovery of 104 MO black holes in globular clusters, and robust nature of the M-sigma relationship spanning galaxies to globular clusters (~5 orders of magnitude in mass), has regenerated interest in the cosmic black hole mass distribution and formation scenarios. Possible insight may be inherent in two classes of objects; the narrow-line seyfert 1 galactic nuclei (NLS1s) and the "ultraluminous" X-ray sources found in various nearby external galaxies. NLS1s may represent an early stage of AGN evolution, with characteristically lower black hole masses, and the ULXs have also been suggested to be objects of intermediate (~102-104 MO) mass. We present preliminary results of an effort to constrain the black hole masses of these objects from analysis of their X-ray spectra. The emergent spectrum of an accretion driven source is modeled as a convolution of a thermal source associated with the accretion flow and a scattering function representing effects of Comptonization by energetic electrons. We describe our methods to extract the intrinsic black body component from the emergent Comptonized spectrum. This additionally involves the determination of the color-to-effective temperature ratio, or ''color factor''. We present our analysis leading to an empirical determination of the color factor, based a number of well studied galactic X-ray binaries, including GRO J1655-40, XTE J1550-564 and GRS 1915+105. Each of these objects have mass-estimates based on dynamical studies of the binary system, and have been observed over large range of luminosities. We then apply the resulting value of the color factor to our spectral analysis of a sample of NLS1s and ULXs, and present the inferred mass determinations.

The author(s) of this abstract have provided an email address for comments about the abstract: shrader@grossc.gsfc.nasa.gov

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