Previous abstract Next abstract
We present results of a multiwavelength/multi-diagnostic investigation of clusters of galaxies containing wide-angle tailed (WAT) radio sources. We attempt to support or refute the hypothesis that a cluster-subcluster merger is responsible for creating the WAT radio source and the properties of the surrounding cluster. Multifiber spectroscopy using the Steward Observatory 2.3 meter is employed to survey redshifts in 10 clusters containing WATs which are well-studied in the radio. Several substructure tests are applied to these data to search for the remnant of a core-passing subcluster. The redshift samples are generally small due to the poorness and distance of the clusters, but the addition of X-ray and CCD images help corroborate substructure in many cases. New ROSAT PSPC data are utilized for a subset of the clusters with redshift data, and Einstein data exist for the remaining clusters.
The WAT clusters show many or all of the properties expected in our merger scenario. First, they are non-cooling flow clusters - any pre-existing cooling flow has been disrupted. Second, these clusters show clumpy X-ray emission near the core with asymmetric extensions between the tails of the WAT. This is suggestive of shocked gas oscillating along the direction of merger and shaping the radio tails via ram pressure. Third, the central dominant galaxy producing the WAT either has no significant peculiar velocity, or has a peculiar velocity which disappears when a suspected subcluster is removed. Finally, the cluster kinematics reveal the presence of a dispersing subcluster.
This study shows that the shaping of WAT radio tails is more likely due to the motion of the intracluster gas relative to the cluster than the motion of the dominant galaxy. Hence, this radio morphology can constrain the state of the gas component in the cluster core. The subcluster merger may even ignite the radio source, but alternative means exist for creating the radio source, such as galaxy mergers, which are difficult to rule out.
Friday program listing