Infrared properties of the SDSS-maxBCG galaxy clusters

¹ Centre d'Etude Spatiale des Rayonnements, CNRS/Université de Toulouse, 9 Avenue du Colonel Roche, BP 44346, 31028 Toulouse Cedex 04, France e-mail: mauro.roncarelli@cesr.fr
² Laboratoire d'Astrophysique de Toulouse-Tarbes, Université de Toulouse, CNRS, 14 Av. Edouard Belin, 31400 Toulouse, France

Received: 19 June 2009
Accepted: 5 January 2010

Abstract

Context. The physics of galaxy clusters has proven to be influenced by several processes connected with their galactic component which pollutes the intracluster medium (ICM) with metals, stars and dust. However, it is not clear whether the presence of diffuse dust can play a role in clusters physics since a characterisation of the infrared (IR) properties of galaxy clusters is very challenging and yet to be completely achieved.

Aims. In our study we focus on the recent work of Giard et al. (2008, A&A, 490, 547) who performed a stacking analysis of the IRAS data in the direction of several thousands of galaxy clusters, providing a statistical characterisation of their IR luminosity and redshift evolution. We model the IR properties of the galactic population of the SDSS-maxBCG clusters (0.1<z<0.3) in order to check if it accounts for the entire observed signal and to constrain the possible presence of other components, like dust in the ICM.

Methods. Starting from the optical properties of the galaxies of the SDSS-maxBCG clusters, we estimate their emission in the 60 and 100 μm IRAS bands making use of modeled spectral energy distributions of different spectral types (E/S0, Sa, Sb, Sc and starburst). We also consider the evolution of the galactic population/luminosity with redshift.

Results. The total galactic emission, which is dominated by the contribution of star-forming late-type galaxies, is consistent with the observed signal. In fact, our galactic emission model slightly overestimates the observed fluxes, with the excess being concentrated in low-redshift clusters ().

Conclusions. Our results indicate that, if present, the IR emission from intracluster dust must be very small compared to the one associated to the galaxy members. This translates into an upper limit on the dust-to-gas mass ratio in the ICM of  × 10^-5. The excess in luminosity obtained at low redshift constitutes an indication that the cluster environment is driving a process of star-formation quenching on its galaxy members.