Another Collision for the Coma Cluster
  We describe a wavelet transform analysis of the ROSAT PSPC images of the Coma cluster. On small scales, ~< 1', the wavelet analysis shows substructure dominated by two extended sources surrounding the two brightest cluster galaxies NGC 4874 and NGC 4889. On slightly larger scales, ~2', the wavelet analysis reveals a filament of X-ray emission originating near the cluster center, curving to the south and east for ~25' in the direction of the galaxy NGC 4911, and ending near the galaxy NGC 4921. These results extend earlier ROSAT observations and further indicate the complex nature of the cluster core. We consider two possible explanations for the production of the filamentary feature as arising from interactions of the main cluster with a merging group. The feature could arise from either ram pressure stripped gas or a dark matter perturbation of tidally stripped material. 
A. Vikhlinin, W. Forman, C. Jones (CfA)