On the X-Ray and Mass Distribution in the Merging Galaxy Cluster 1E 0657−56: Ram Pressure-Stripping in Substructures with an NFW Density Profile

We investigate the X-ray and mass distribution in the merging galaxy cluster1E 0657-56. We study head-on collisions of two virialized clusters with an NFWdensity profile in the $\Lambda$CDM universe using an N-body + hydrodynamicalcode. A clear off-set of an X-ray peak from a mass peak, which is like what isreported in Clow et al. (2004), is first reproduced in the N-body +hydrodynamical simulations. We estimate the ram pressure-stripping conditionsof the substructure in mergers of two NFW dark halos using a simple analyticalmodel. We find that the ram pressure dominates the gravity of the substructurewhen the smaller cluster's mass is less than approximately one tenth of thelarger cluster's mass. The characteristic X-ray and mass structures found in 1E0657-56 suggest that neither the ram pressure nor the gravitational bound forceoverwhelms the other and that the mass ratio between the progenitors is nearthe critical value mentioned above.Comment: 5 pages, 3 figures, Accepted for publication in PAS