Complex X-ray morphology of Abell 3128: A distant cluster behind a disturbed cluster - AstrophysicsReportar como inadecuado

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Abstract: We present here the results of a detailed study of the X-ray properties ofthe cluster of galaxies Abell 3128 z=0.06, based on the analysis of deep 100ks XMM-Newton data. The most obvious feature of the X-ray morphology of A3128is the presence of two X-ray peaks separated by ~12-. By detecting theredshifted Fe K line, we find that the Northeast NE X-ray peak observedtoward A3128 is a distant luminous cluster of galaxies at redshift z=0.44. Oursubsequent optical spectroscopic observation of a distant radio bright galaxyin the centre of the NE X-ray peak with the Magellan telescope also revealed aredshift of z=0.44, confirming the association of the galaxy with the clusterseen in X-rays. We detect a gravitational arc around the galaxy. The propertiesof this galaxy indicate that it is the cD galaxy of the cluster in thebackground. The properties of the Southwest X-ray peak suggest that it is thecore of a group merging with A3128 along our line of sight. Based on 2D maps ofthermodynamic properties of the intra-cluster medium determined aftersubtracting a model for the background cluster, we conclude that an enhancedsurface brightness region at a distance of ~2.8- from the centre of the galaxydistribution is the centre of the gravitational potential of the cluster A3128.The unrelaxed nature of A3128 can be attributed to its location in the highdensity environment of the Horologium-Reticulum supercluster.

Autor: N. Werner, E. Churazov, A. Finoguenov, M. Markevitch, R. Burenin, J. S. Kaastra, H. Boehringer


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