The distorted jets and gaseous environment of 3C 465

Abstract

The interaction of the jets seen in radio galaxies with any surrounding gaseous medium has been shown to provide a useful diagnostic for the physical parameters of the jets themselves. In this paper, ROSAT HRI observations of the field around the wide-angle-tailed radio galaxy 3C 465 are used to derive the properties of the intracluster medium (ICM) through which the radio jets propagate. If the observed large-scale bends in the jets are attributed to ram pressure and buoyancy within this medium, then the morphology of the bent large-scale jets constrains the transverse velocity of the radio galaxy to be ≲280km s-1. The bulk flow of material down the large-scale jet cannot be occurring at a velocity of ≳3000km s-1; as expected, this value is very much smaller than the velocity previously inferred for the pc-scale jet (∼0.6c). As in many radio galaxies, there is an abrupt transition from the well-collimated small-scale radio jets to the extended large-scale lobe structure in 3C 465. One possible explanation for this transition is that it occurs at the interface between the interstellar medium (ISM) of the galaxy and the surrounding ICM. We have used the HRI data to measure the properties of the ISM of the host galaxy. These data, together with those obtained from larger radii, are consistent with the hypothesis that the jet/lobe transition coincides with the ISM/ICM interface, but data of higher spatial and spectral resolution are required to test this model more stringently.