Discovery of a giant radio halo in a massive merging cluster at z = 0.443

Abstract

We have discovered a giant radio halo in the massive merging cluster MACSJ0417.5-1154. This cluster, at a redshift of 0.443, is one of the most X-ray luminous galaxy cluster in the MAssive Cluster Survey (MACS) with an X-ray luminosity in the 0.1-2.4 keV band of 2.9×1045 erg s - 1. Recent observations from GMRT at 230 and 610 MHz have revealed a radio halo of ˜ 1.2 × 0.3 Mpc2 in extent. This halo is elongated along the North-West, similar to the morphology of the X-ray emission from Chandra. The 1400 MHz radio luminosity (L r) of the halo is ˜2 × 1025 W Hz - 1, in good agreement with the value expected from the L x - L r correlation for cluster halos.