Jet termination in wide-angle tail radio sources

Abstract

Wide-angle tail radio galaxies (WATs) are an uncommon class of radio sources with luminosities near the FRI/FRII break, and are usually associated with central cluster galaxies. Their defining characteristic when imaged sensit ively at high resolution is their twin, well-collimated jets, which can persist with low opening angle for tens of kpc before flaring into long, often bent plumes. Although several m odels for the jet termination have been proposed, the majority of them are unsatisfactory when confronted with observations. Here we present the results of a programme of radio observations made with the aims of showing that objects classified as WATs do all have well-collimated jets and seeing in detail how the jets disrupt as they enter the plumes. We show that compact, ‘hotspot-like’ features at the ends of the jets are common bu t by no means universal, and discuss the constraints that this places on models of the jet-plume transition. We discuss the properties of the observed well-collimated jet s and, using relativistic beaming models, estimate their speed to be � 0.3c. Finally, we show that the distance from the galactic centre at which the base of the plume is found is related to the temperature of the host cluster.