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

Abstract

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 200Y500 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 of the plane of the sky. The outflow has deposited upward of 10 61 ergs into the cluster gas, most of which was propelled beyond the inner $100 kpc cooling region. The supermassive black hole has accreted at a rate of approximately 0.1Y0.25 M yr À1 over this time frame, which is a small fraction of the Eddington rate of a $10 9 M 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.

The jet feedback mechanism (JFM) in stars, galaxies and clusters

“…In some cooling flows two opposite chains of bubbles that are close to each other, and even overlap, are observed, as in Hydra A (Wise et al 2007), and in two bubbles in the galaxy group NGC 5813 (Randall et al , 2015. These chains are usually attributed to several episodes of jet activity.…”

“…Over the years the AGN feedback mechanism, mostly by jet-inflated bubbles, has been solidified (e.g., Dong et al 2010;O'Sullivan et al 2011;Farage et al 2012;Gaspari et al 2012a,b;Birzan et al 2011;Gitti et al 2012;Pfrommer 2013). Key to the establishment of the AGN-JFM in cooling flows are the many observations of X-ray deficient bubbles (e.g., Boehringer et al 1993;Fabian et al 2000;McNamara et al 2001;Heinz et al 2002;Forman et al 2007;Wise et al 2007;Baldi et al 2009;David et al 2009;Gastaldello et al 2009;Gitti et al 2010;Blanton et al 2011;David et al 2011;Machacek et al 2011;Randall et al 2011;Doria et al 2012;Pandge et al 2012;Hlavacek-Larrondo et al 2015). Many of these X-ray bipolar structures resemble visible bipolar structures observed in bipolar PNe (see Figs.…”

“…A strong evidence for cyclical JFM comes from clusters where two or more bipolar pairs of bubbles are seen, such as Perseus (e.g. Fabian et al 2000) and Hydra A (e.g., Wise et al 2007). In some other types of systems reviewed here the launching processes might be continues, but a cyclical variation might take place because of an orbital motion, such that the location of the jet-launching changes; such is the case in the CEE, GEE, and ILOTs.…”

Far-ultraviolet morphology of star-forming filaments in cool core brightest cluster galaxies

“…The centroids of all panels are aligned, with east left and north up. (Wise et al 2007). An X-ray unsharp mask, FUV continuum map, and optical unsharp mask are shown in the left-hand, centre, and right-hand panels, respectively.…”

An overview of jet-mode AGN feedback and the prospects for studying its cosmic evolution with LOFAR

“…Additionally, the outbursts create weak shocks (Wise et al 2007), with energies comparable to the cavity enthalpies (Brüggen et al 2007); sound waves ; and heat through cosmic rays (CRs) injected at the tips of the jets (Böhringer & Morfill 1988;Loewenstein et al 1991;Enßlin et al 1997;Guo & Oh 2008;Enßlin et al 2011;Wiener et al 2013;Pfrommer 2013), all of which produce a convective core and provide heating isotropically (Tabor & Binney 1993;Chandran & Rasera 2007;Sharma et al 2009). AGN heating can also come from radiative-mode AGN such as quasars (Ciotti & Ostriker 1997 or through primordial CRs from blazars (Pfrommer et al 2012).…”