ChandraObservation of the Cluster of Galaxies MS 0839.9+2938 atz= 0.194: The Central Excess Iron and Type Ia Supernova Enrichment

We present the Chandra study of the intermediately distant cluster ofgalaxies MS 0839.9+2938. By performing both the projected and deprojectedspectral analyses, we find that the gas temperature is approximately constantat about 4 keV in 130-444h_70^-1 kpc. In the inner regions, the gas temperaturedescends towards the center, reaching <~ 3 keV in the central 37h_70^-1 kpc.This infers that the lower and upper limits of the mass deposit rate are 9-34M_sun yr^-1 and 96-126 M_sun yr^-1, respectively within 74h_70^-1 kpc where thegas is significantly colder. Along with the temperature drop, we detect asignificant inward iron abundance increase from about 0.4 solar in the outerregions to about 1 solar within the central 37h_70^-1 kpc. Thus MS 0839.9+2938is the cluster showing the most significant central iron excess at z>~ 0.2. Weargue that most of the excess iron should have been contributed by SNe Ia. Byutilizing the observed SN Ia rate and stellar mass loss rate, we estimate thatthe time needed to enrich the central region with excess iron is 6.4-7.9 Gyr,which is similar to those found for the nearby clusters. Coinciding with theoptical extension of the cD galaxy (up to about 30h_70^-1 kpc), the observedX-ray surface brightness profile exhibits an excess beyond the distributionexpected by either the beta model or the NFW model, and can be well fitted withan empirical two-beta model that leads to a relatively flatter mass profile inthe innermost region.Comment: Accepted for publication in Ap