Very High Iron Abundance of the Hot Gas around the cD Galaxy of the MKW 4 Cluster

Abstract

We observed a nearby X-ray-bright poor cluster MKW 4 with Chandra. The iron abundance is found to increase dramatically from 0.3 to 1.3 solar within 150" of the cD galaxy NGC 4073. Then MKW 4 is the second cluster to exhibit a significantly high metallicity of greater than 1 solar, after the Centaurus Cluster. Weakness of the central cool component helps us to obtain the metallicity free from the multitemperature effects. The scale of temperature decrease toward the center region is clearly different from that of abundance increment, indicating that these are not the same phenomena. Since the stellar-to-intracluster mass ratio around NGC 4073 is very high compared to other cD type clusters, it is no doubt that the abundance increment is due to metal ejection from the cD galaxy. The iron-to-stellar mass ratio around NGC 4073 is 6.2×10^-3, and thus most of the ejected iron still remains in the vicinity of NGC 4073. By comparing the stellar distribution with that of iron, the steady state outflow speed of iron is roughly estimated to be 2.4 km s^-1, which is faster than the Coulomb diffusion.