Discovery of a Large-Scale Abundance Gradient in the Cluster of Galaxies AWM7 with ASCA

A large-scale gradient in the metal abundance has been detected with ASCA from an X-ray bright cluster of galaxies AWM7. The metal abundance shows a peak of 0.5 solar at the center and smoothly declines to <~ 0.2 solar at a radius of 500 kpc. The gas temperature is found to be constant at 3.8 keV. The radial distribution of iron can be fit with a beta-model with beta ~ 0.8 assuming the same core radius (115 kpc) as that of the intracluster medium. The metal distribution in AWM7 suggests that the gas injected from galaxies is not efficiently mixed in the cluster space and traces the distribution of galaxies.