Discovery of a Giant Radio Halo in a New Planck Galaxy Cluster PLCKG171.9-40.7.

摘要

We report the discovery of a giant radio halo in a new, hot, X-ray luminous galaxy cluster recently found by Planck, PLCKG171.9-40.7. The radio halo was found using Giant Metrewave Radio Telescope observations at 235 MHz and 610 MHz, and in the 1.4 GHz data from a NRAO Very Large Array Sky Survey pointing that we have reanalyzed. The diffuse radio emission is coincident with the cluster X-ray emission, has an extent of approx.1 Mpc and a radio power of approx. 5X10(exp 24)W/Hz at 1.4 GHz. Its integrated radio spectrum has a slope of alpha approx. = 1.8 between 235 MHz and 1.4 GHz, steeper than that of a typical giant halo. The analysis of the archival XMMNewton X-ray data shows that the cluster is hot (approx. 10 keV) and disturbed, consistent with X-ray selected clusters hosting radio halos. This is the first giant radio halo discovered in one of the new clusters found by Planck.