2005MNRAS.357..381R

We present an observation of the radio galaxy 3C 401 and the surrounding intracluster medium (ICM) of its host galaxy cluster by the Chandra X-ray Observatory. This luminous radio galaxy is notable in that it has characteristics intermediate between the Fanaroff-Riley type I and II morphologies. We clearly detect point-like emission coincident with the radio core of 3C 401, although the spatial resolution of even Chandra is only 2 kpc at the distance of 3C 401 (z= 0.201) and so the possibility remains that this is a dense (and rapidly cooling) thermal gaseous core in the centre of the ICM atmosphere. Strong departures from spherical symmetry in the central 10-20 kpc of the ICM clearly suggest interaction between the ICM and the radio lobes of 3C 401. A central X-ray bar probably results from the evacuation of two ICM cavities by the expanding radio lobes. Beyond these central regions, the cluster possesses a flatter profile than many clusters of comparable mass, suggesting the importance of ICM heating and entropy injection by 3C 401. We detect an interesting cross-like structure in the ICM on 100 kpc scales. We speculate that this could be a radio-galaxy-induced disturbance corresponding to a time when 3C 401 was substantially more powerful. A particularly exciting possibility is that this cross-like structure corresponds to a large-scale global g-mode oscillation excited by a past outburst of 3C 401.