Chandra Observations of the X-ray Jet in Centaurus A

Abstract

We present high angular resolution X-ray images and spectra from two {\em Chandra} ACIS-I observations of the X-ray jet in the nearby radio galaxy Centaurus A. We find that the X-ray emission from the jet is composed of a low surface brightness diffuse component extending continuously from within at least 60 pc of the active nucleus into the NE radio lobe 4 kpc from the nucleus, along with 31 discrete compact knots, most of which are extended at the resolution of our observation. We find that there are small but significant differences between the X-ray and radio morphologies of the inner jet at the arcsecond level, making it unlikely that a single, spatially coincident population of ultrarelativistic electrons is responsible for the emission in both energy regimes. We suggest that the X-ray knots of the inner jet are indeed the sites of particle acceleration and shocks, and the X-ray and radio knot offsets are caused by a combination of particle diffusion and energy loss. These offsets may be a common feature of all jets in radio galaxies, or at least jets in FR I type galaxies, and may be fundamental to the physics of such jets. The X-ray spectra of several regions of the jet are well fit by absorbed power-law models with photon indices $\sim$2.2-2.5, although the spectrum of one bright knot located $\sim$1 kpc from the nucleus (knot B) is harder (photon index = 2.0).