RADIO JET PROPAGATION AND WIDE-ANGLE TAILED RADIO-SOURCES IN MERGING GALAXY CLUSTER ENVIRONMENTS

The intracluster medium (ICM) within merging clusters of galaxies is l ikely to be in a violent or turbulent dynamical state which may have a significant effect on the evolution of cluster radio sources. We pres ent results from a recent gas + N-body simulation of a cluster merger, suggesting that mergers can result in long-lived, supersonic bulk flo ws, as well as shocks, within a few hundred kiloparsecs of the core of the dominant cluster. These results have motivated our new two-dimens ional and three-dimensional simulations of jet propagation in such env ironments. The first set of simulations models the ISM/ICM transition as a contact discontinuity with a strong velocity shear. A supersonic (M(j) = 6) jet crossing this discontinuity into an ICM with a transver se, supersonic wind bends continuously, becomes ''naked'' on the upwin d side, and forms a distended cocoon on the downwind side. In the case of a mildly supersonic jet (M(j) = 3), however, a shock is driven int o the ISM and ISM material is pulled along with the jet into the ICM. Instabilities excited at the ISM/ICM interface result in the jet repea tedly pinching off and reestablishing itself in a series of ''disconne ction events.'' The second set of simulations deals with a jet encount ering a shock in the merging cluster environment. A series of relative ly high-resolution two-dimensional calculations is used to confirm ear lier analysis predicting that the jet will not disrupt when the jet Ma ch number is greater than the shock Mach number. A jet which survives the encounter with the shock will decrease in radius and disrupt short ly thereafter as a result of the growth of Kelvin-Helmholtz instabilit ies. We also find, in disagreement with predictions, that the jet flar ing angle decreases with increasing jet density. Finally, a three-dime nsional simulation of a jet crossing an oblique shock gives rise to a morphology which resembles a wide-angle tailed radio source with the j et flaring at the shock and disrupting to form a long, turbulent tail which is dragged downstream by the postshock wind.