Galaxy and hot gas distributions in the z = 0.52 galaxy cluster RBS 380 from CHANDRA and NTT observations

¹ Institute für Physik, Universität Potsdam, Am Neuen Palais 10, 14469 Potsdam, Germany
² Institut für Astrophysik, Universität Innsbruck, Technikerstr. 25, 6020 Innsbruck, Austria e-mail: Sabine.Schindler@uibk.ac.at

Corresponding author: R. Gil-Merino, rmerino@astro.physik.uni-potsdam.de

Received: 19 May 2003
Accepted: 17 June 2003

Abstract

We present CHANDRA X-ray and NTT optical observations of the distant  galaxy cluster RBS 380 – the most distant cluster of the ROSAT Bright Source (RBS) catalogue. We find diffuse, non-spherically symmetric X-ray emission with a X-ray luminosity of  erg/s, which is lower than expected from the RBS. The reason is a bright AGN in the centre of the cluster contributing considerably to the X-ray flux. This AGN could not be resolved with ROSAT. In optical wavelength we identify several galaxies belonging to the cluster. The galaxy density is at least 2 times higher than expected for such a X-ray faint cluster, which is another confirmation of the weak correlation between X-ray luminosity and optical richness. The example of the source confusion in this cluster shows how important high-resolution X-ray imaging is for cosmological research.