Astronomy and Astrophysics Radio Emission from the A3571 Cluster Complex: the Final Stage of a Cluster Merger?

In this paper we report and discuss the results of a radio survey in the A3571 cluster complex, a structure located in the Shapley Concentration core, and formed by the three clusters A3571, A3572 and A3575. The survey was carried out simultaneously at 22 cm and 13 cm with the Australia Telescope Compact Array, and led to the detection of 124 radio sources at 22 cm. The radio source counts in this region are in agreement with the background counts. Among the 36 radio sources with optical counterpart, six have measured red-shift which places them at the distance of the A3571 cluster complex, and nine radio sources have optical counterparts most likely members of this cluster complex. All radio galaxies emit at low power level, i.e. logP 22cm (W Hz −1) ≤ 22.6. A number of them are likely to be starburst galaxies. The radio luminos-ity function of early type galaxies is in agreement with that derived by Ledlow & Owen (1996) if we restrict our analysis to the A3571 cluster. On the basis of the multiwavelength properties of the A3571 cluster complex, we propose that it is a very advanced merger, and explain the radio properties derived from our study in the light of this hypothesis. A&A manuscript no. Your thesaurus codes are: missing; you have not inserted them