A Chandra Study of the Effects of a Major Merger on the Structure of A2319

Abstract

We present an analysis of a Chandra observation of the massive, nearby galaxy cluster A2319. A sharp surface brightness discontinuity-suggested by previous, lower angular resolution X-ray imaging-is clearly visible in the ACIS image. This ~300 kpc feature suggests that a major merger is taking place with a significant velocity component perpendicular to the line of sight. The cluster emission-weighted mean temperature is 11.8+/-0.6 keV, somewhat higher than previous temperature measurements. The Chandra temperature map of A2319 reveals substructure resembling that anticipated based on hydrodynamic simulations of cluster mergers and shows an associated cool core not previously known. The map shows a separation between the intracluster medium (ICM) and galaxies of one subcluster, indicating a transient state in which the ICM has been stripped from the subcluster galaxies (and presumably the dark matter). Detailed analysis of the merger feature shows a pressure change across the surface brightness discontinuity by a factor of