What determines the properties of the X-ray jets in Fanaroff-Riley type I radio galaxies?

Abstract

We present the first large sample investigation of the properties of jets in Fanaroff-Riley type I radio galaxies (FR I) based on data from the Chandra archive. We explore relations between the properties of the jets and the properties of host galaxies in which they reside. We find previously unknown correlations to exist, relating photon index, volume emissivity, jet volume and luminosity, and find that the previously long held assumption of a relationship between luminosities at radio and X-ray wavelengths is linear in nature when bona fide FR I radio galaxies are considered. In addition, we attempt to constrain properties which may play a key role in the determination of the diffuse emission process. We test a simple model in which large-scale magnetic field variations are primarily responsible for determining jet properties; however, we find that this model is inconsistent with our best estimates of the relative magnetic field strength in our sample. Models of particle acceleration should attempt to account for our results if they are to describe FR I jets accurately.