Mon. Not. R. Astron. Soc., 379, 518-534 (2007/August-1)
X-ray and Sunyaev-Zel'dovich scaling relations in galaxy clusters.
MORANDI A., ETTORI S. and MOSCARDINI L.
Abstract (from CDS):
We present an analysis of the scaling relations between X-ray properties and Sunyaev-Zel'dovich (SZ) parameters for a sample of 24 X-ray luminous galaxy clusters observed with Chandra and with measured SZ effect. These objects are in the redshift range 0.14-0.82 and have X-ray bolometric luminosity L ≳ 1045 erg/s, with at least 4000 net counts collected for each source. We perform a spatially resolved spectral analysis and recover the density, temperature T and pressure profiles of the intracluster medium (ICM), just relying on the spherical symmetry of the cluster and the hydrostatic equilibrium hypothesis. The combined analysis of the SZ and X-ray scaling relations is a powerful tool to investigate the physical properties of the clusters and their evolution in redshift, by tracing out their thermodynamical history. We observe that the correlations among X-ray quantities only are in agreement with previous results obtained for samples of high-z X-ray luminous galaxy clusters. On the relations involving SZ quantities, we obtain that they correlate with the gas temperature with a logarithmic slope significantly larger than the predicted value from the self-similar model. The measured scatter indicates, however, that the central Compton parameter y0 is a proxy of the gas temperature at the same level of other X-ray quantities like luminosity. Our results on the X-ray and SZ scaling relations show a tension between the quantities more related to the global energy of the system (e.g. gas temperature, gravitating mass) and the indicators of the structure of the ICM (e.g. gas density profile, central Compton parameter y0). Indeed, by using a robust fitting technique, the most significant deviations from the values of the slope predicted from the self-similar model are measured in the L-T, L -Mtot, Mgas-T, y0-T relations. When the slope is fixed to the self-similar value, these relations consistently show a negative evolution suggesting a scenario in which the ICM at higher redshift has lower both X-ray luminosity and pressure in the central regions than the expectations from self-similar model. These effects are more evident in relaxed clusters in the redshift range 0.14-0.45, where a more defined core is present and the assumed hypotheses on the state of the ICM are more reliable.
2007 The Authors. Journal compilation © 2007 RAS
galaxies: clusters: general - cosmic microwave background - cosmology: observations - X-rays: galaxies: clusters
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