Discovery of an X-ray cavity near the radio lobes of Cygnus A indicating previous AGN activity

摘要: Cygnus A harbours the nearest powerful radio jet of an Fanaroff-Riley (FR) class II galaxy in a cluster where interaction with intracluster medium (ICM) can be studied detail. We use large set Chandra archival data, VLA and new LOFAR observations to shed light on jets ICM. identify X-ray cavity distribution emitting plasma region south Cyg nucleus which has lower pressure than surrounding medium. The show that is filled synchrotron plasma. spectral age buoyancy time indicates at least as current not much larger twice this time. suggest was created previous active phase when energy output Active Galactic Nucleus (AGN) about two orders magnitude less today.