Radial temperature profiles for a large sample of galaxy clusters observed with XMM-Newton^*

¹ Università degli Studi di Milano, Dip. di Fisica, via Celoria 16, 20133 Milano, Italy
² INAF-IASF Milano, via Bassini 15, 20133 Milano, Italy e-mail: leccardi@iasf-milano.inaf.it

Received: 8 February 2008
Accepted: 8 April 2008

Abstract

Aims. We measure radial temperature profiles as far out as possible for a sample of ≈50 hot, intermediate redshift galaxy clusters, selected from the XMM-Newton archive, keeping systematic errors under control.

Methods. Our work is characterized by two major improvements. First, we used background modeling, rather than background subtraction, and the Cash statistic rather than the . This method requires a careful characterization of all background components. Second, we assessed systematic effects in detail. We performed two groups of tests. Prior to the analysis, we made use of extensive simulations to quantify the impact of different spectral components on simulated spectra. After the analysis, we investigated how the measured temperature profile changes, when choosing different key parameters.

Results. The mean temperature profile declines beyond 0.2 R₁₈₀. For the first time, we provide an assessment of the source and the magnitude of systematic uncertainties. When comparing our profile with those obtained from hydrodynamic simulations, we find the slopes beyond ≈0.2 R₁₈₀ to be similar. Our mean profile is similar but somewhat flatter with respect to those obtained by previous observational works, possibly as a consequence of a different level of characterizing systematic effects.

Conclusions. This work allows us to not only constrain cluster temperature profiles in outer regions with confidence, but also, from a more general point of view, to explore the limits of the current X-ray experiments (in particular XMM-Newton) with respect to the analysis of low surface-brightness emission.