The intracluster iron distribution around 4 C + 55 . 16

We report on the metal distribution in the intracluster medium around the radio galaxy 4C+55.16 (z = 0.24) observed with the Chandra X-ray Observatory. The radial metallicity profile shows a dramatic change at 10 arcsec (∼ 50 kpc) in radius from half solar to twice solar at inner radii. Also found was a plume-like feature located at∼ 3 arcsec to the south-west of the centre of the galaxy, which is mostly accounted for by a strong enhancement of iron L emission. The X-ray spectrum of the plume is characterized by the metal abundance pattern of Type Ia supernovae (SNeIa), i.e., large ratios of Fe to α-elements, with the iron metallicity being unusually high at 7.9 −5.0 solar (90 per cent error). How the plume has been formed is not entirely clear. The inhomogeneous iron distribution suggested in this cluster provides important clues to understanding the metal enrichment process of the cluster medium.