The radio luminosity function of radio galaxies in distant clusters

摘要

A complete sample of 18 X-ray selected clusters of galaxies belonging to the ROSAT North Ecliptic Pole (NEP) survey has been observed with the Very Large Array at 1.4 GHz. These are the most distant clusters in the X-ray survey with redshift in the range 0.3 < z < 0.8. 79 radio sources are detected within half an Abell radius with an observed peak brightness >= 0.17 mJybeam(-1). 32 out of the 79 sources are within 0.2 Abell radius, 22 of them are considered cluster members based on spectroscopic redshifts or their optical magnitude and morphological classification. The cluster radio galaxies are used to construct the radio luminosity function (RLF) of distant X-ray selected clusters. A comparison with two nearby cluster RLFs shows that the NEP RLF lies above the local ones, has a steeper slope at low radio powers (<= 10(24) W Hz(-1)) and shows no evidence for a break at approximate to 6 x 10(24) W Hz(-1) which is observed in the nearby cluster RLFs. (c) 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.