Speaker: Prof. Farhad Yusef-Zadeh, Northwestern University
Abstract: The central region of our Galaxy (the inner few hundred parsecs of the Galactic center) is different from the rest of the Galaxy in its interstellar medium properties. This region is centered on a supermassive, 4 million-solar-mass black hole (Sgr A*) and is occupied by a large concentration of a warm molecular gas with high density, high velocity dispersion, high gas temperature, and high cosmic ray flux. Gas clouds in this region are subject to the strong tidal field that may suppress star formation in this region. I will give an overview of our work on the Galactic center, including the origin of the 6.4 keV line emission from molecular clouds, discovered in recent years, as well as the evidence for star formation near Sgr A*. In one model, the 6.4 keV emission results from X-ray irradiation by a hypothetical transient source associated with the massive black hole Sgr A*. Alternatively, relativistic particles from local nonthermal sources impact diffuse neutral gas producing bremsstrahlung emission and the 6.4 keV line emission.