XMM-Newton Observation of IC 310 in the Outer Region of the Perseus Cluster of Galaxies

We present results from an XMM-Newton observation of the head-tail radio galaxy IC 310 located in the southwest region of the Perseus cluster. The spectrum is well fitted by an absorbed power-law model with a photon index of 2.50 ± 0.02 without significant absorption excess. The X-ray image shows a point-like emission at IC 310 without any sign of a structure correlated with the radio halo tail. The temperature of the intracluster medium surrounding IC 310 declines as a function of distance from the cluster center, from kT ∼ 6 keV in the northeast corner of the field of view to about 3keV in the southwest region. Although we do not find any sharp edges in the surface brightness profile, a brightness excess of about 20% over a smooth β model is seen. The temperature also rises by about 10% in the same region. This indicates that the IC 310 region is a subcluster probably infalling into the Perseus cluster, and the gas in front of IC 310 towards the Perseus cluster is likely to be compressed by the large-scale motion, which supports the view that the IC 310 system is undergoing a merger.