The X-Ray Jet in Centaurus A: Clues to the Jet Structure and Particle Acceleration

We report detailed studies of the X-ray emission from the kiloparsec-scale jet in the nearest active galaxy, Centaurus A. By analyzing the highest quality X-ray data obtained with the Chandra ACIS-S, 41 compact sources (mostly bright jet knots) were found within the jet on angular scales less than 4 00 , 13 of which were newly identified. We construct the luminosityfunction for the detected jetknots and arguethat the remainingemissionis most likely to be truly diffuse, rather than resulting from the sum of many unresolved fainter knots. We subtracted the contributions of the bright knots from the total X-ray jet flux, and show that the remaining extended emission has a relatively flattoppedintensityprofileinthetransversejetdirection,withtheintensitypeakingatthejetboundariesbetween50 00 and 170 00 . We note that limb-brightened morphologies have been observed previously at radio frequencies in a few FR I and FR II jet sources, but never so clearly at higher photon energies. Our result therefore supports a stratified jet model,consisting of arelativistic outflow including a boundary layer with a velocity shear. In addition, we found that theX-rayspectrumofthediffusecomponentisalmost uniformacross andalongthejet, withanX-rayenergyspectral