Recent X-ray and Sunyaev-Zel ’ dovich ( SZ ) observations have dramatically increased the number of known distant galaxy clusters .
In some merging , low-redshift ( z < 0.4 ) clusters , centrally-located , diffuse , extended radio emission ( called radio halos ) has been found .
Using the Giant Metrewave Radio Telescope ( GMRT ) , we report the detection of diffuse radio emission in the binary-merging cluster PLCK G147.3–16.6 located at z = 0.65 .
We classify the emission as a giant radio halo due to the large physical extent of about 0.9 Mpc and low-surface brightness .
We measure an integrated flux density of 7.3 \pm 1.1 mJy at 610 MHz for the radio halo , resulting in a 1.4 GHz radio power of 5.1 ~ { } \times 10 ^ { 24 } W Hz ^ { -1 } .
The radio halo power is consistent with that expected from the known correlation between X-ray luminosity or the cluster integrated SZ signal and radio power .
Our observations also suggest that more of these distant radio halos could be discovered with the GMRT .