[Previous] | [Session 32] | [Next]

[32.09] Chandra X-Ray StudY of Sgr A-East

Y. Maeda (Penn State), F. Baganoff, M. W. Bautz (MIT), W. N. Brandt, D. Burrows, E. D. Feigelson, G. P. Garmire (Penn State), M. Morris (UCLA), G. R. Ricker (MIT), T. Townsley (Penn State), ACIS GTO 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 nonthermal shell-like radio source Sgr~A East which is now clearly resolved from other complex structures in the region. The X-ray emitting region is ~30\arcsec (1.2 pc) extent and is centrally concentrated within the radio shell; no emission is seen from the shell itself. The spectrum shows strong K\alpha lines from highly ionized ions of S, Ar, Ca and Fe. A simple isothermal plasma model gives temperature kT ~2~keV, absorption N_H ~q 1 \times 10²³ cm^-2, luminosity L_{\rm x} ~8 \times 10³⁴ ergs s^-1 in the 2--10 keV band, and gas mass 2 \eta^\frac{1}{2} M_\odot with a filling factor \eta. The plasma appears to be rich in heavy elements, a factor ~4 above solar levels, and iron concentration appears to be stratified towards the interior.

The energetics and size of the X-ray emission support the hypothesis that Sgr~A East is a single SNR, arising either from a Type Ia or Type II supernova from a M \approx 10-20 M_\odot star. It has a 'mixed morphology' (centrally concentrated X-rays within a radio shell) and is similar to the SNR W49B. From velocity shear and other arguments, we infer its age is probably ~10,000 yr. The relationship between Sgr~A East and the supermassive black~hole Sgr~A* is discussed.

This research was supported by NASA grant NAS8-38252.