An XMM-Newton view of the cluster of galaxies Abell 85

¹ Institut d'Astrophysique de Paris, CNRS, 98bis Bd Arago, 75014 Paris, France e-mail: durret@iap.fr
² Instituto de Astronomia, Geofísica e C. Atmosf./USP, R. do Matão 1226, 05508-090 São Paulo/SP, Brazil
³ Harvard Smithsonian Center for Astrophysics, 60 Garden St, Cambridge MA 02138, USA

Received: 15 July 2004
Accepted: 17 November 2004

Abstract

We have observed the cluster of galaxies Abell 85 with XMM-Newton. These data have allowed us in a previous paper to confirm the existence of the extended 4 Mpc filament detected by the ROSAT PSPC in the neighbourhood of this cluster, and to determine an X-ray temperature of about ~keV. We now present a thorough analysis of the properties of the X-ray gas in the cluster itself, including temperature and metallicity maps for the entire cluster. These results show that Abell 85 had intense merging activity in the past and is not fully relaxed, even in the central region. We have also determined the individual abundances for some iron-group metals and α-elements in various regions; the ratios of these metallicities to the iron abundance show that both supernova types Ia and II must be involved in the intra-cluster gas enrichment. Spectral analysis of the central region suggests a different redshift of the X-ray emitting gas compared to the mean cluster velocity derived from galaxy member redshifts. We discuss the implications of the difference between the cD galaxy redshift, the mean galaxy redshift and the hot gas redshift, as well as the possibility of several groups being accreted on to Abell 85. Finally, we obtain the dynamical mass profile and baryon fraction taking into account the newly determined temperature profile. The dynamical mass in Abell 85 has a steep density profile, similar to the ones found in N-body simulations.