DUST IN CLUSTERS: SEPARATING THE CONTRIBUTION OF GALAXIES AND INTRACLUSTER MEDIA

We have analyzed a sample of 327 clusters of galaxies, spanning the range of 0.06–0.70 in redshift. Strong constraints on their mean intracluster emission of dust have been obtained using maps and catalogs from the Herschel MerMES project; within a radius of 5 arcmin centered in each cluster, the 95% C.L. limits obtained are 86.6, 48.2, and 30.9 mJy at the observed frequencies of 250, 350, and 500 μ m. From these restrictions, and assuming physical parameters typical of interstellar media in the Milky Way, we have obtained tight upper limits on the visual extinction of background galaxies due to the intracluster media (ICM): A _V (95% C.L.) ≲ 10⁻³ mag. Strong constraints are also obtained for the mass of such dust; for instance, using the data at 350 μ m we establish a 95% upper limit of <10⁹ M _⊙ within a circle with a radius of 5 arcmin centered in the clusters. This corresponds to a fraction of the total mass of the clusters of 9.5 × 10⁻⁶, and indicates a deficiency in the gas-to-dust ratio in the ICM by about three orders of magnitude in relation to the value found in the Milky Way. Computing the total infrared luminosity of the clusters in three ranges of redshift (0.05–0.24, 0.24–0.42, and 0.42–0.71) and two ranges of mass (<10¹⁴ and >10¹⁴ M _⊙), respectively, a strong evolution of luminosity in redshift ( L ∼ z ^1.5) for both ranges of masses is found. The results indicate a strong declining in star formation rate with time in the last ∼6 Gyr.