The Interaction of 3C 401 with the Surrounding Intra-Cluster Medium

$^1$Dept. of Astronomy, University of Maryland, College Park, MD 20742, USA.
$^2$Dept. of Astrophysics and Planetary Science, University of Colorado, Boulder, CO 80309,USA.

In press

Abstract:

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 FRI and FRII morphologies. We clearly detect point-like emission coincident with the radio-core of 3C 401, although the spatial resolution of even Chandra is only 2kpc 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 center of the ICM atmosphere. Strong departures from spherical symmetry in the central 10-20kpc 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 100kpc 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.