Chandra observation of abell 2142: Survival of dense subcluster cores in amerger

We use Chandra data to map the gas temperature in the central region of the merging cluster A2142. The cluster is markedly nonisothermal; it appears t hat the central cooling flow has been disturbed but not destroyed by a merg er. The X-ray image exhibits two sharp, bow-shaped, shocklike surface brigh tness edges or gas density discontinuities. However, temperature and pressu re profiles across these edges indicate that these are not shock fronts. Th e pressure is reasonably continuous across these edges, while the entropy j umps in the opposite sense to that in a shock (i.e., the denser side of the edge has lower temperature, and hence lower entropy). Most plausibly, thes e edges delineate the dense subcluster cores that have survived a merger an d ram pressure stripping by the surrounding shock-heated gas.