AWM 4 and MKW 4 - two very different poor clusters observed with XMM-Newton

Abstract

We present observations of two poor clusters, AWM 4 and MKW 4, observed by XMM-Newton. Both systems are relaxed, with little substructure evident in their X-ray halos or galaxy populations. However, their temperature structures are markedly different, with AWM 4 isothermal to the resolution of the EPIC instruments while MKW 4 shows a strong decline in temperature towards the core. Metal abundance also increases more strongly in the core of MKW 4 than AWM 4. Three dimensional models show further differences, suggesting that gas in the core of AWM 4 has been heated and has expanded outwards. The dominant elliptical galaxy of AWM 4 hosts an AGN with large-scale radio jets, while the central cD of MKW 4 shows no current AGN activity. We therefore conclude that the difference in activity cycle of the AGN in the two galaxies is responsible for the difference in IGM properties between the two clusters.