AAS 201st Meeting, January, 2003
Session 31. The Galactic Center and Its Environs
Oral, Monday, January 6, 2003, 2:00-3:30pm, 6AB

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[31.07] Complex Spatio-Spectral Structure of Diffuse X-ray Emission in the Central 20 Parsecs of the Milky Way

S. Park (Penn State), F. K. Baganoff, M. W. Bautz (MIT), G. P. Garmire (Penn State), Y. Maeda (ISAS), M. Morris (UCLA), M. P. Muno (MIT)

Over the last three years, the Galactic center region has been monitored with a series of the Chandra/ACIS observations. Besides the target object Sgr A*, the massive Galactic black hole candidate, the surrounding diffuse X-ray emission has been detected within the ~17' x 17' ACIS field of view. As of 2002 June, combining 11 GTO and GO observations, the total effective exposure reaches ~590 ks, which reveals the details of the faint diffuse X-ray emission with significant photon statistics. We here present early results from the imaging/spectral analyses of these data. The ``true-color'' X-ray images of this region indicate that the diffuse X-ray emission features have complex spatio-spectral structures represented by various atomic line emission and hard continuum. We construct the equivalent width (EW) images for the detected elemental species Si, S, Ar, Ca, and Fe in order to map the distributions of these atomic emission lines in the Galactic center. We detect strong enhancements of He-like Fe within the ~1.3' diameter region to the immediate east of Sgr A*. This is most likely emission from the highly ionized Fe associated with the recently X-ray identified supernova remnant (SNR) Sgr A East. A large-scale enhancement of the 6.4 keV Fe EW in the north-east of Sgr A* is in general spatially coincident with the molecular cloud M-0.02-0.07, which may be interpreted as emission from the X-ray reflection nebulae or fast-moving SN ejecta fragments. In the soft band (1.5 - 4.5 keV), we detect a network of loop-like structures with a few arcmin angular scales around the Galactic center. The soft X-ray loop in the southeast of Sgr A* is identified with the Galactic radio SNR G359.92-0.09, where we detect thermal emission interior to the soft X-ray loops. We detect a bright non-thermal X-ray knot as a part of the southwest boundary of G359.92-0.09 which is spatially coincident with a bright radio knot of the SNR. The best-fit power law spectrum appears harder than typical shock accelerated synchrotron emission and may have a non-thermal bremsstrahlung origin. The soft X-ray loop in the southwest of Sgr A* is filled with thermal emission from highly ionized Fe, but we find no radio SNR counterpart for this feature. We also report results from other diffuse filamentary features which show various spectral/morphological characteristics with thermal/non-thermal origins. This work was supported by NASA under contract NAS8-01128.

The author(s) of this abstract have provided an email address for comments about the abstract: park@astro.psu.edu

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Bulletin of the American Astronomical Society, 34, #4
© 2002. The American Astronomical Soceity.