The Dark Matter Haloes of Chandra X-ray Galaxy Clusters and Baryons Effect

TL;DR

This study analyzes Chandra X-ray observations of 129 galaxy clusters to measure dark matter and baryonic content, confirming known correlations and revealing that the inner density slope decreases with increasing baryonic mass.

Contribution

It provides the largest dataset of mass parameters for galaxy clusters and demonstrates a correlation between the inner density slope and baryonic mass content.

Findings

Confirmed the c-M relation consistent with simulations.

Measured the inner slope alpha of the density profile.

Found alpha decreases with increasing baryonic mass.

Abstract

We present results based on Chandra observations of a large sample of 129 hot galaxy clusters. We measure the concentration parameter c_200, the dark mass M_200 and the baryonic mass content in all the objects of our sample, providing the largest dataset of mass parameters for galaxy clusters in the redshift range z = 0.01 - 1.4. We confirm a that a tight correlation between c_200 and M_200, c \propto M^a_vir /(1+z)^b with a = -0.56 +/- 0.15 and b =0.80 +/- 0.25 (68 per cent confidence limits), is present, in good agreement with the predictions from numerical simulations and previous observations. Fitting the mass profile with a generalized NFW model, we got the inner slope alpha, with alpha = 0.94 +/- 0.13. Finally, we show that the inner slope of the density profile, alpha correlates with the baryonic mass content, M_b : namely alpha is decreasing with increasing baryonic mass content.