A Comparison of the ISM in Ellipticals to the Hot Gas in a Dense Group from Combined ROSAT and ASCA Observations

Abstract

We analyze diffuse X-ray emission from NGC4649, NGC5044 and NGC5846, combining data from two X-ray observatories, ROSAT and ASCA. With ASCA, we perform a detailed analysis of the X-ray emission which properly accounts for the ASCA PSF and also include a 3-dimensional source model. All three sources exhibit cooling flows in their centers. From the derived abundances of Si, S and Fe, we conclude that NGC5044 (a dense group of galaxies) was able to retain significant amounts of gas during an early galaxy wind phase. Fe abundance in NGC5846 (normal E galaxy) corresponds to current SNIa rate of ~0.2 of Tammann rate, while low Fe mass in NGC4649 (normal E in the Virgo cluster) could be an environmental effect.