English

Cygnus A

Astrophysics 2007-05-23 v1

Abstract

We report Chandra imaging-spectroscopy and RXTE spectroscopy of the nearby, powerful radio galaxy Cygnus A. Various aspects of the results are discussed, including the X-ray properties of the nucleus, the radio hot spots, the cluster of galaxies, the prolate cavity in the ICM inflated by the radio jets and ``bands'' of thermal gas which encircle the cavity in its equatorial plane. The hard X-ray emission of the nucleus extends to 100 keV and originates from an unresolved source absorbed by a large column density (NH_{\rm H} \simeq 2 ×\times 1023^{23} cm2^{-2}) of gas. The soft (<< 2 keV) nuclear emission exhibits a bi-polar structure which extends \simeq 2 kpc from the nucleus and is strongly correlated with both optical continuum and emission-line morphologies. It is suggested that this nebulosity is photoionized by the nucleus and that the extended X-rays are electron-scattered nuclear radiation. All four radio hot spots are detected in X-rays, with the emission resulting from synchrotron self-Compton radiation in an approximately equipartition field. The temperature of the X-ray emitting intracluster gas drops from 8\simeq 8 keV more than 100 kpc from the center to 5\simeq 5 keV some 80 kpc from the center, with the coolest gas immediately adjacent to the radio galaxy. There is a metallicity gradient in the X-ray emitting gas, with the highest metallicities (\sim solar) found close to the center, decreasing to 0.3\sim 0.3 solar in the outer parts. (Abstract truncated).

Keywords

Cite

@article{arxiv.astro-ph/0202319,
  title  = {Cygnus A},
  author = {A. S. Wilson and K. A. Arnaud and D. A. Smith and Y. Terashima and A. J. Young},
  journal= {arXiv preprint arXiv:astro-ph/0202319},
  year   = {2007}
}

Comments

9 pages, 12 figures, to be published in ``New Visions of the Universe in the XMM-Newton and Chandra Era'', Ed. F. Jansen (in press) (2002) (European Space Agency ESA SP-488)