Reconstructing the merger history of the A3266 galaxy cluster

A temperature map of the A3266 galaxy cluster has been derived from the ASC A gas imaging spectrometer observations. It shows an asymmetric pattern of heating indicative of an ongoing merger between a group-sized subcluster an d the main cluster. The galaxy distribution shows two peaks connected in a barlike structure running northeast to southwest through the central region of the main cluster, defining the merger axis. The temperature of the inte rgalactic medium generally decreases from southwest to northeast along the merger axis with a peak of 13.2(-2.0)(+3.4) keV in a region which is perpen dicular to the merger axis and extends through the main cluster density pea k. The central bar has a velocity dispersion of similar to 1300 km s(-1), c ompared to similar to 1000 km s(-1) for the surrounding cluster. The centra l bar also has two distinct density peaks in the distribution of galaxies, yet it has a velocity distribution which is consistent with a single Gaussi an. This implies a merger in the plane of the sky. The optical and X-ray da ta taken together show that a loose group of similar to 30 galaxies has pen etrated the main cluster from the southwest, decoupling from their original intergroup medium and passing through a strong shock front. Two radio gala xies, one a wide angle tail (WAT) morphology and the other a narrow angle t ail (NAT), are located to the southwest of the main cluster in the postshoc k gas. Since the merger is in the plane of the sky, a dynamical analysis ca nnot be applied to derive the velocity of the merger. Alternatively, using the pre- and postshock gas temperature and assuming an adiabatic shock, we calculate a relative gas velocity of similar to 1400 km s(-1). The alignmen t of the NAT and WAT relative to the shock front combined with the high gas velocity from the merger implies that the observed radio morphologies form ed via ram pressure as a result of the merger.