We have performed broad-band CCD imaging of a sample of 24 low luminosity radio galaxies containing radio jets. Their optical properties, photometric parameters, and their local environments have been studied and compared with other samples of radio galaxies.
Radio galaxies can be classified in two groups, powerful radio galaxies (PRG, with total power P≥ 1025 W Hz-1 at 1.4 GHz) and low luminosity radio galaxies (LLRG, with total power P≤ 1025 W Hz-1 at 1.4 GHz), both from their radio as well as their optical properties. Among the main works that allowed to establish the differences in line emission, photometric structure, and environment between the two classes we should mention those by Hine and Longair (1979), Heckman et al. (1985, 1986), Lilly and Prestage (1987), Owen and Laing (1989), and Smith and Heckman (1989a, b). PRG usually show Fanaroff-Riley type II radio morphology (Fanaroff and Riley 1974), strong optical emission lines, and photometric structure similar to normal ellipticals. LLRG generally show FR I morphology, weak emission lines or pure absorption line spectra, and optical luminosity and light profiles similar to bright cluster galaxies.
One feature that powerful and low luminosity radio galaxies have in common is the morphological evidence of ongoing or past interaction/merging processes in these systems (Heckman et al. 1986; Lilly and Prestage 1987; Smith and Heckman 1989a, b; Colina and Pérez-Fournon 1990a, b; González-Serrano and Pérez-Fournon 1992 and references therein). However the indications of interaction of each class appear in different form.