Extended X-ray emission from the BL Lac object PKS 0521-365
Abstract
Models that seek to unify BL Lacs and low-power radio galaxies predict that the two types of object should show similar isotropically emitted X-ray emission. Testing this is usually limited by difficulties in separating strong X-ray emission from a BL Lac nucleus and surrounding low-surface brightness emission. In this paper we report ROSAT HRI observations of the z=0.055 BL Lac object PKS 0521-365. We are able to separate a luminous extended X-ray component from the bright nucleus. Using a new radio map, we show that it is unlikely that the extended emission is due to inverse-Compton scattering of photons from the active nucleus, and instead interpret it as thermal emission from dense, rapidly cooling gas. This is a more extreme environment than is found in typical FRI radio galaxies, and may pose a problem for unified models.
Cite
@article{arxiv.astro-ph/9812148,
title = {Extended X-ray emission from the BL Lac object PKS 0521-365},
author = {M. J. Hardcastle and D. M. Worrall and M. Birkinshaw},
journal= {arXiv preprint arXiv:astro-ph/9812148},
year = {2009}
}
Comments
10 pages, 5 figures, to appear in MNRAS