Self-similarity of clusters of galaxies and the relation

Free access article

Issue		A&A Volume 373, Number 3, July III 2001


Page(s)		L33 - L36
Section		Letters
DOI		http://dx.doi.org/10.1051/0004-6361:20010770

A&A 373, L33-L36 (2001)
DOI: 10.1051/0004-6361:20010770

Self-similarity of clusters of galaxies and the $L_{\sf X}{-} T$ relation

D. M. Neumann and M. Arnaud

CEA/Saclay DSM/DAPNIA/ Service d'Astrophysique, L'Orme des Merisiers, Bât. 709, 91191 Gif-sur-Yvette, France
e-mail: marnaud@discovery.saclay.cea.fr

(Received 27 April 2001 / Accepted 28 May 2001 )

Abstract
In this paper based on ROSAT/PSPC data we investigate the emission measure profiles of a sample of hot clusters of galaxies (kT> 3.5 keV) in order to explain the differences between observed and theoretically predicted $L_{\rm X}$ -T relation. Looking at the form of the emission measure profiles as well as their normalizations we find clear indication that indeed the profiles have similar shapes once scaled to the virial radius, however, the normalization of the profiles shows a strong temperature dependence. We introduce a $M_{\rm gas}$ -T relation with the dependence . This relationship explains the observed $L_{\rm X}$ -T relation and reduces the scatter in the scaled profiles by a factor of 2 when compared to the classical scaling. We interpret this finding as strong indication that the $M_{\rm gas}$ -T relation in clusters deviates from classical scaling.

Key words: galaxies: clusters: general -- cosmology: observations, dark matter -- X-rays: general

Offprint request: D. M. Neumann, ddon@cea.fr

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