Dust in 3CR radio galaxies: On the FR1-FR2 difference
Abstract
We compare three 3CR samples of 11 FR1 galaxies, 17 FR2 galaxies and 18 lobe-dominated quasars contained in the ISO Data Archive. In contrast to the powerful FR2 galaxies with edge-brightened lobes, the low radio power FR1 galaxies in our sample do not exhibit any high MIR or FIR dust luminosity, which is typical for a buried, intrinsically more luminous AGN. This consolidates the fact already inferred from optical studies that their AGNs have only a relatively low luminosity. Also the FR1 galaxies show a high FIR/MIR luminosity ratio, compared to quasars, suggesting that their FIR luminosity is substantially powered by the interstellar radiation field (ISRF) of the giant elliptical hosts. Finally, we discuss the FR1-FR2 morphological dichotomy. FR1 galaxies do not have more interstellar matter (ISM) than FR2s as traced -- on the large scale -- by the cool FIR emitting dust and -- in the nuclear region -- by the warm MIR emitting dust. Due to the lack of central gas we suggest that the black holes of our FR1 galaxies are fed at a lower accretion rate than those of the FR2 galaxies.
Cite
@article{arxiv.astro-ph/0409719,
title = {Dust in 3CR radio galaxies: On the FR1-FR2 difference},
author = {S. A. H. Mueller and M. Haas and R. Siebenmorgen and U. Klaas and K. Meisenheimer and R. Chini and M. Albrecht},
journal= {arXiv preprint arXiv:astro-ph/0409719},
year = {2009}
}
Comments
4 pages 3 figures Letter accepted by A&A