This suggests that the FR II radio phenomenon occurs in normal elliptical galaxies, preferentially in the most massive ones. A comparison sample of line-less galaxies in the SDSS follows exactly the same relation, although the masses are, on average, smaller. We find that the black hole masses and stellar masses in FR II galaxies are very closely related: â€˜MBHâ€™âˆM1.13* with very little scatter. Two of them have double-peaked emission lines and deserve more attention. A few objects are, on the contrary, ionized by a softer radiation field. Compared to classical active galactic nuclei (AGN) hosts in the main galaxy sample of the SDSS, our FR II galaxies show a larger proportion of objects with very hard ionizing radiation field and large ionization parameter. Radio galaxies with hotspots are found among the ones with the highest values of P1.4 GHz/â€˜MBHâ€™.

We find that the properties of FR II galaxies are mainly driven by the Eddington parameter LHÎ±/â€˜MBHâ€™ or, equivalently, P1.4 GHz/â€˜MBHâ€™. We also find a very strong correlation between the values of LHÎ± and P1.4 GHz when scaled by â€˜MBHâ€™, an estimate of the black hole mass. We show that the absence of emission lines in about one third of our sample is likely due to a detection threshold and not to a lack of optical activity. We find that the luminosity in the HÎ± line - which we argue gives a better measure of the total emission-line flux than the widely used luminosity in - is strongly correlated with the radio luminosity P1.4 GHz. Starting from the Cambridge Catalogues of radio sources, we have created a sample of 401 Fanaroff-Riley type II ( FR II) radio sources that have counterparts in the main galaxy sample of the seventh Data release of the Sloan Digital Sky Survey (SDSS) and analyse their radio and optical properties.

FR II radio galaxies in the Sloan Digital Sky Survey: observational facts

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