Chandra observations of A 2670 and A 2107: A comet galaxy and cDs with large peculiar velocities

We present an analysis of Chandra observations of the galaxy clusters A 2670 and A 2107. Their cD galaxies have large peculiar velocities (> 200 km s-1) and thus the clusters appear to be undergoing mergers. In A 2670, we find a comet-like structure around one of the brightest galaxies. At the leading edge of the structure, there is a cold front. The mass of the X-ray gas in the comet-like structure suggests that the galaxy was in a small cluster or group, and its intracluster medium is being stripped by ram-pressure. The regions of cool interstellar medium of the cD galaxies in A 2670 and A 2107 are very compact. This is similar to the brightest galaxies in the Coma cluster, which is also a merging cluster. In each galaxy, the short cooling time of the ISM requires a heating source; the compact nature of the ISM makes it unlikely that the heating source is a central active galactic nucleus. © 2006. Astronomical Society of Japan.