G.A. Mamon, F. Combes, C. Deffayet and B. Fort (eds)
EAS Publications Series, 20 (2006) 179-182
Tracing the X-ray emitting intra-cluster medium of clusters of galaxies beyond R200
AIM – Unité Mixte de Recherche CEA – CNRS – Université Paris VII – UMR 7158 CEA/Saclay; DSM/DAPNIA/Service d'Astrophysique, CEA/Saclay L'Orme des Merisiers Bât. 709, 91191 Gif-sur-Yvette, France
We present here a study of a sample of 14 nearby clusters of galaxies (0.06 < z < 0.1) observed with the ROSAT/PSPC. We convert the X-ray surface brightness profiles of the clusters into emission measure profiles scaled to the classical scaling relations based on the spherical collapse model. We sort the clusters into different temperature bins and stack the scaled emission measure (ScEM) profiles of clusters belonging to the same bin together. This method enhances the statistics of the profiles – especially in outer regions. The stacked profiles allow us to observe a signal out to radii r > r200. Fitting beta-models to the overall ScEM profiles we find for the different subsamples rc = 0.15-0.18 r200 and β = 0.8, which is higher than the canonical value of β = 2/3 often found. The beta-model is generally a better representation for hotter than for cooler clusters. We see indications for continuous steepening of the profiles with increasing radius: at radii r > 0.8 r200 the profiles are systematically below the beta-model curve with β = 0.8.
© EAS, EDP Sciences, 2006