HI in nearby radio sources

Among the sources where HI is detected, gas with kinematics deviating from regular rotation is more likely found as the radio power increases.In the great majority of these cases, the HI profile is asymmetric with a significant blue-shifted component. This is particularly common for sources with logP_1.4GHz_>24W/Hz, where the radio emission is small, possibly because these radio sources are young. The same is found for sources that are bright in the mid-infrared, i.e. sources rich in heated dust.In these sources, the HI is outflowing likely under the effect of the interaction with the radio emission.

Conversely, in dust-poor galaxies, and in sources with extended radio emission, at all radio powers we only detect HI distributed in a rotating disk. Stacking experiments show that in sources for which we do not detect HI in absorption directly, the HI has a column density that is lower than 3.5x10^17^(T_spin_/c_f_)cm^-2^. We use our results to predict the number and type of HI absorption lines that will be detected by the upcoming surveys of the Square Kilometre Array precursors and pathfinders (Apertif, MeerKAT, and ASKAP).