Physical properties of jets in low-luminosity radio sources

Abstract

The results of fitting Bicknell's semiempirical turbulent jet model to a sample of 23 jets taken from the B2 extragalactic radio sources studied in detail using the VLA are presented. It is found that the model fits are generally very reasonable and that the single most important parameter in the fits is the ratio of galaxy virial temperature to interstellar medium temperature. In most cases, where there are two jets within the same galaxy the inferred galaxy atamosphere parameters are almost identical. All jets are initially light with respect to the interstellar medium (ISM) and eventually approach density equilibrium through entrainment. The Mach numbers for most jets are in the range from 1 to 3. However, a high-Mach number subsample can be identified for which the Mach numbers could be as high as 10. Significantly these jets are lighter, better collimated, and more powerful than the rest of the sample, supporting the notion that the transition from class I to class II radio sources represents, in large part, a transition from low- to high-Mach number jets. 21 refs.