The Complete Local Volume Groups Sample - II. A study of the Central
  Radio Galaxies in the High$-$Richness Sub-sample
  We present a study of the radio properties of the dominant early-type
galaxies in 26 galaxy groups, the high-richness sub-sample of the Complete
Local-volume Groups Sample (CLoGS). Combining new 610 MHz and 235 MHz
observations of 21 groups from the Giant Metrewave Radio Telescope (GMRT) with
archival GMRT and Very Large Array (VLA) survey data, we find a high detection
rate, with 92% of the dominant galaxies hosting radio sources. The sources have
a wide range of luminosities, 10$^{20}$ $-$ 10$^{24}$ W/Hz in the 235 and 610
MHz bands. The majority (54%) are point-like, but 23% have radio jets, and
another 15% are diffuse radio sources with no clear jet/lobe morphology. The
spectral index of the detected radio sources ranges from very flat values of
~0.2 to typical radio synchrotron spectra of ~0.9 with only two presenting
steep radio spectra with $\alpha_{235}^{610}$ > 1. We find that jet sources are
more common in X-ray bright groups, with radio non-detections found only in
X-ray faint systems. Radio point sources appear in all group environments
irrespective of their X-ray properties or spiral fraction. We estimate the
mechanical power (Pcav) of the jet sources in the X-ray bright groups to be
10$^{41}$ $-$ 10$^{43}$ erg/s, with the two large-scale jet systems (NGC 193
and NGC 4261) showing jet powers two orders of magnitude greater than the
radiative losses from the cool cores of their groups. This suggests that
central AGN are not always in balance with cooling, but may instead produce
powerful periodical bursts of feedback heating.
