X-Ray Supercavities in the Hydra A Cluster and the Outburst History of the Central Galaxy's Active Nucleus

A 227 ks Chandra X-ray image of the hot plasma in the Hydra A cluster has revealed an extensive cavity system. The system was created by a continuous outflow or a series of bursts from the nucleus of the central galaxy over the past 200-500 Myr. The cavities have displaced 10% of the plasma within a...

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Bibliographic Details
Published in:The Astrophysical journal 2007-04, Vol.659 (2), p.1153-1158
Main Authors: Wise, M. W, McNamara, B. R, Nulsen, P. E. J, Houck, J. C, David, L. P
Format: Article
Language:English
Subjects:
Astronomy
Earth, ocean, space
Exact sciences and technology
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Summary:A 227 ks Chandra X-ray image of the hot plasma in the Hydra A cluster has revealed an extensive cavity system. The system was created by a continuous outflow or a series of bursts from the nucleus of the central galaxy over the past 200-500 Myr. The cavities have displaced 10% of the plasma within a 300 kpc radius of the central galaxy, creating a swiss-cheese-like topology in the hot gas. The surface brightness decrements are consistent with empty cavities oriented within 40 degree of the plane of the sky. The outflow has deposited upward of 10 super(61) ergs into the cluster gas, most of which was propelled beyond the inner similar to 100 kpc cooling region. The supermassive black hole has accreted at a rate of approximately 0.1-0.25 M [unk] yr super(-1) over this time frame, which is a small fraction of the Eddington rate of a similar to 10 super(9) M [unk] black hole, but is dramatically larger than the Bondi rate. Given the previous evidence for a circumnuclear disk of cold gas in Hydra A, these results are consistent with the AGN being powered primarily by infalling cold gas. The cavity system is shadowed perfectly by 330 MHz radio emission. Such low-frequency synchrotron emission may be an excellent proxy for X-ray cavities and thus the total energy liberated by the supermassive black hole.
ISSN:0004-637X
1538-4357
DOI:10.1086/512767