This award supports collaboration between Mitchell Begelman and his research group at the University of Colorado, and Ruediger Staubert and others of the Institute for Astronomy and Astrophysics of the University of Tuebingen, Germany. They are studying the origin of the hard X-ray component in emissions from hot coronae around accretion disks. In particular, they are attempting to develop a set of self-consistent models through numerical analysis which can then be used more widely by other astronomers. The collaborative plan combines the theoretical skills in modeling active galaxies possessed by Begelman and his graduate student, James Dove, with the data acquisition and analysis skills of Professor Staubert and his colleagues. The latter has been one of the leading groups in the world in the study of high energy phenomena in x-ray binaries and other systems. The U.S. side will be responsible for developing computer code and the basic theoretical models; these models will be greatly improved by the physical data obtained by the German group. The technique of x-ray spectroscopy has improved substantially, and now produces x-ray spectral data that is high enough quality to warrant detailed theoretical modeling. This project brings together two research groups with the complementary expertise to accomplish this task and improve understanding of accretion disk coronae.
