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Y. Maeda (Penn. State U.), F. Baganoff (MIT), E. Feigelson (Penn. State U.), M. Bautz (MIT), W. Brandt, D. Burrows (Penn. State U.), J. Doty (MIT), G. Garmire (Penn. State U.), M. Morris (UCLA), S. Pravdo (JPL), G. Ricker (MIT), L. Townsley (Penn. State U.), ACIS Team
The Chandra X-ray Observatory recently observed the Galactic Center region with the ACIS instrument. This paper reports on X-ray emission from the non-thermal shell-like radio source Sgr~A East which is now clearly resolved from the complex structures in the region. The size of the X-ray emission region is ~30\arcsec (HPD) and centrally fills the radio shell. The spectrum contains K\alpha lines from highly ionized ions of S, Ar, Ca and Fe which can be modeled with optically thin emission from a thermal plasma having a temperature of ~2~keV and a luminosity of ~\times1034 ergs s-1 in the 2--10 keV band. The plasma appears to be rich in heavy elements, over-abundant by roughly a factor of four with respect to solar abundances. Furthermore, iron atoms appear to be concentrated towards the interior of the source by a factor of two compared to the outer regions, while the lighter atoms seem to be uniformly distributed. The total gas mass of the plasma is 2 \eta\frac{1}{2} M\odot, with a filling factor \eta. The X-ray properties support the hypothesis that Sgr~A East is a single SNR that exploded ~04 yrs ago, probably of Type Ia or II with a progenitor mass M \approx 10-20 M\odot. The radio properties (the non-thermal shell with high \Sigma-D ratio and the surrounding dust shell) might be consistent with the centrally filled morphology in X-rays if we consider an expansion of a SNR into the ambient materials as dense as 103 cm-3. The relationship between Sgr~A East and the supermassive black~hole Sgr~A* is discussed.
This research was supported by NASA contract NAS 8-38252. The research was performed in part (SHP) by JPL, under contract with NASA.