XMM-Newton observations of Sagittarius A East

Abstract

We present an analysis of a recent XMM-Newton observation of Sgr A East, a supernova remnant located close to the Galactic Centre. Very high-quality X-ray spectra reveal many emission lines from highly ionized atoms consistent with a multitemperature thin thermal plasma in ionization equilibrium. We use a two-temperature model to fit the spectra and derive temperatures of 1 and 4 keV. There is significant concentration of iron (Fe) towards the centre of the X-ray source such that the Fe abundance varies from ~4 times solar in the core down to ~0.5 solar in the outer regions, which contrasts with the rather uniform distribution of other metals such as sulphur (S), argon (Ar) and calcium (Ca), which have abundances in the range 1-3. The derived total energy, mass and abundance pattern are consistent with a single supernova event, of either Type Ia or Type II origin, involving a relatively low-mass progenitor star. A weak 6.4-keV neutral Fe fluorescence line is also detected, the illumination source most likely being Sgr A East itself. The morphology and spectral characteristics of Sgr A East show no clear linkage to putative past activity in Sgr A*.