MeerKAT Massive Distant Clusters Survey

Diffuse radio halos are detected in eight clusters (27%), while 21 systems (70%) show no central diffuse emission down to some of the deepest upper limits yet obtained at these redshifts; one additional target is excluded because of poor data quality.

The detected halos lie along the established P_1.4GHz_-M_500_ scaling relation measured at low redshift, whereas non-detections populate the lower envelope of the radio power-mass plane, broadly consistent with the known bimodality in this relation. No cluster-scale radio relics or mini-halos are identified in the sample. Mock halo injection simulations are used to derive 3{sigma} upper limits for 18 clusters, showing that a substantial fraction of the high-redshift population remains below current MeerKAT sensitivity at L-band.