FRIICAT: A FIRST catalog of FR II radio galaxies^⋆

¹ INAF–Osservatorio Astrofisico di Torino, via Osservatorio 20, 10025 Pino Torinese, Italy
e-mail: capetti@oato.inaf.it
² Dipartimento di Fisica, Università degli Studi di Torino, via Pietro Giuria 1, 10125 Torino, Italy
³ Department of Physics and Astronomy, University of Southampton, Highfield, SO17 1BJ, UK

Received: 14 December 2016
Accepted: 30 January 2017

Abstract

Aims. We built a catalog of 122 FR II radio galaxies, called FRIICAT, selected from a published sample obtained by combining observations from the NVSS, FIRST, and SDSS surveys. The catalog includes sources with redshift ≤ 0.15, an edge-brightened radio morphology, and those with at least one of the emission peaks located at radius r larger than 30 kpc from the center of the host.

Methods. The radio luminosity at 1.4 GHz of the FRIICAT sources covers the range L_1.4 ~ 10^39.5−10^42.5erg s^-1. The FRIICAT catalog has 90% of low and 10% of high excitation galaxies (LEGs and HEGs), respectively. The properties of these two classes are significantly different. The FRIICAT LEGs are mostly luminous (−20 ≳ M_r ≳ −24), red early-type galaxies with black hole masses in the range 10⁸ ≲ M_BH ≲ 10⁹M_⊙; they are essentially indistinguishable from the FR Is belonging to the FRICAT. The HEG FR IIs are associated with optically bluer and mid-IR redder hosts than the LEG FR IIs and to galaxies and black holes that are smaller, on average, by a factor ~2.

Results. FR IIs have a factor ~3 higher average radio luminosity than FR Is. Nonetheless, most (~ 90%) of the selected FR IIs have a radio power that is lower, by as much as a factor of ~100, than the transition value between FR Is and FR IIs found in the 3C sample. The correspondence between the morphological classification of FR I and FR II and the separation in radio power disappears when including sources selected at low radio flux thresholds, which is in line with previous results. In conclusion, a radio source produced by a low power jet can be edge brightened or edge darkened, and the outcome is not related to differences in the optical properties of the host galaxy.