We report on the X-ray emission from the shell-like, non-thermal radio source Sgr A East located in the inner few parsecs of the Galaxy based on observations made with the ACIS detector on board the Chandra X-ray Observatory. The X-ray emission from Sgr A East is concentrated within the central ≃2 pc of the larger radio shell. The spectrum shows strong Kα lines from highly ionized ions of S, Ar, Ca, and Fe. A simple isothermal plasma model gives electron temperature ∼2 keV, absorption column ∼1 × 1023 H cm-2, luminosity ∼8 × 1034 ergs s-1 in the 2-10 keV band, and gas mass ∼2η1/2 M⊙ with a filling factor η. The plasma appears to be rich in heavy elements, over-abundant by roughly a factor of four with respect to solar abundances. Accompanied with filamentary or blob-like structures, the plasma shows a spatial gradient of elemental abundance: the spatial distribution of iron is more compact than that of the lighter elements. These Chandra results strongly support the long-standing hypothesis that Sgr A East is a supernova remnant (SNR). Since Sgr A East surrounds Sgr A* in projection, it is possible that the dust ridge compressed by the forward shock of Sgr A East hit Sgr A* in the past, and the passage of the ridge may have supplied material to accrete onto the black hole in the past, and may have removed material from the black hole vicinity, leading to its present quiescent state.
All Science Journal Classification (ASJC) codes
- Astronomy and Astrophysics
- Space and Planetary Science