The Origin of the High-Energy Activity at the Galactic Center

Farhad Yusef-Zadeh(1), William Purcell(1), & Eric Gotthelf(2)

Paper: To be published in Proc. of 4th Compton Symp.,

Weblink: http://www.astro.nwu.edu/astro/faculty/farhad/papers.html

Recent X-ray and gamma-ray observations of the Galactic center region by the ASCA and CGRO/EGRET instruments show evidence of 2-10 keV and >1 GeV continuum emission as well as 6.7 and 6.4 keV line emission from the inner 0.2^o of the Galactic center. This region is also known to host a bright nonthermal radio continuum source Sgr A East and a dense molecular cloud M-0.02-0.07 known as the 50 km s^-1 cloud. The oval-shaped nonthermal Sgr A East is physically interacting with M-0.02-0.07 at the Galactic center. A comparison between the distribution of ionized, synchrotron and neutral gas suggests a self-consistent interpretation of the high-energy activity at the Galactic center. Our preliminary analysis of the data suggest a shock model of cosmic ray acceleration at the site of the interaction to explain the enhanced GeV gamma -ray emission. We also address a number of issues related to the spatial correlation of the diffuse radio and X-ray emitting gas as well as to the origin of the fluorescent 6.4 and 6.7 keV emission at the Galactic center.