Interplanetary scintillation studies with MWA

Most of these objects are compact steep-spectrum or MHz-peaked spectrum radio sources. We have used mid-infrared data from the Wide-field Infrared Survey Explorer (WISE) catalogue to search for the host galaxies of 65 strongly scintillating MWA sources and compare their properties with those of the overall population of bright low-frequency radio sources.

We identified WISE mid-infrared counterparts for 91 per cent of the bright sources in a single 900deg^2^ MWA field, and found that the hosts of the strongly scintillating sources were typically at least 1mag fainter in the WISE W1 (3.4{mu}m) band than the hosts of weakly scintillating MWA sources of similar radio flux density. This difference arises mainly because the strongly scintillating sources are more distant. We estimate that strongly scintillating MWA sources have a median redshift of z~1.5, and that at least 30 per cent of them are likely to lie at z>2.