Rubin 9602568 This award supports a 24 month Science and Technology Agency of Japan (STA) Postdoctoral Fellowship for Dr. Bradley Rubin at the Institute of Physical and Chemical Research (RIKEN) in Tokyo, Japan. Dr. Rubin will work with Dr. Masaru Matsuoka, Director of the Cosmic Radiation Laboratory at RIKEN, on a research project entitled "Observations of Cosmic X-Ray Sources". The proposed research will investigate the emission of electromagnetic energy occurring in selected x-ray binary systems with specific emphasis on the analysis of data recorded by orbiting high energy observatories. Soft x-ray transients are a class of x-ray binaries containing a neutron star for which outbursts of strong x-ray emission are occasionally observed. Modeling the high energy spectra in both the quiescent and outburst states is critical to an understanding of the physical structure and outburst mechanisms of these systems. The analysis will discriminate between accretion and shock powered models of the quiescent emission and thermal and non-thermal models of the outburst emission. Research will also focus on another class of x- ray binaries, x-ray pulsars, which emit periodic signals due to the rotation of an accretion powered neutron star. Emission line observations of these systems will be used to obtain information about the density and ionization structure of the surrounding environment. The result of this research in its entirety will be an improved understanding of the nature of these enigmatic objects. ***
