Probing the Off-state of Cluster Giant Radio Halos

We derive the best characterization to date of the properties of radio quiescent massive galaxy clusters through a statistical analysis of their average synchrotron emissivity. We stacked 105 radio images of clusters from the 843 MHz Sydney University Molonglo Sky Survey, all with LX > 1044 erg s−1 and redshifts z < 0.2, after removing point-source… (More)