Deep X-Ray Imaging of the Central 20 Parsecs of the Galaxy with Chandra

Mark Morris1, Fred Baganoff2, Yoshitomo Maeda3, Eric Feigelson4, Marshall Bautz2, Neil Brandt4, George Chartas4, Gordon Garmire4, Leisa Townsley4

1 Dept. of Physics & Astronomy, UCLA, Los Angeles CA 90095-1567, USA
2 Massachusetts Institute of Technology, Center for Space Research, 77 Massachusetts Avenue, Cambridge, MA 02139-4307
3 Inst. of Space & Astronautical Science, 3-1-1 Yoshinodai, Sagamihara, Kanagawa 229-8510, Japan
4 Department of Astronomy & Astrophysics 525 Davey Laboratory, Penn. State Univ., University Park, PA 16802-6305, USA

E-mail contact: morris@astro.ucla.edu

The Galactic center was observed for 0.5 Msec with the ACIS-I instrument on the Chandra X-Ray Observatory between 22 May 2002 and 04 June 2002, with the primary goal of measuring short-term temporal fluctuations from SgrA* (as reported separately by Baganoff at this workshop). A wealth of detail was observed in the ubiquitous, extended emission and over 2000 point sources were detected in the 17'x17' field of view. Here, we describe the extended emission and the point sources located within one parsec (24'') of the center which we have been able to identify with known stars. Diffuse X-ray emission is extended all along the Galactic plane, supplemented by a strong extended source identified with Sgr A East (Maeda et al. 2002, ApJ 570, 671). In addition, a strong X-ray complex appears at L=0.013, B=-0.054, and has no known counterpart at other wavelengths. Perhaps the most suggestive structure is a pair of apparent bipolar X-ray lobes placed roughly symmetrically about Sgr A* at distances of  8.5 pc. These lobes are oriented perpendicular to the Galactic plane, raising the possibility that they have resulted from collimated ejections from the vicinity of SgrA*. The spectra of these features will be discussed in the context of this interpretation. On smaller scales, a number of filamentary X-ray structures have been found within the extended emission structures. Some of these X-ray filaments apparently have radio counterparts. The alternative hypotheses that these be edge-on shocks or linear magnetic filaments akin to nonthermal radio filaments will be discussed. In addition to the X-ray filaments, several other known radio sources are found to have X-ray counterparts. Finally, the spatial relationship between dense interstellar clouds and edges or discontinuities in the extended X-ray emission has been examined in order to decide whether these are absorption edges attributable to foreground absorption or whether they represent density-bounded edges to the hot, X-ray emitting gas distribution.