Large-scale HI in nearby radio galaxies: segregation in neutral gas content with radio source size

We present results of a study of neutral hydrogen (H I) in a complete sample of nearby non-cluster radio galaxies. We find that radio galaxies with large amounts of extended H I ($M_{\rm H{\,\small I}} \gtrsim 10^9~M_{\odot}$) all have a compact radio source. The host galaxies of the more extended radio sources, all of Fanaroff & Riley type-I, do not contain these amounts of H I. We discuss several possible explanations for this segregation. The large-scale H I is mainly distributed in disk- and ring-like structures with sizes up to 190 kpc and masses up to $2 \times 10^{10}~M_{\odot}$. The formation of these structures could be related to past merger events, although in some cases it may also be consistent with a cold-accretion scenario