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Dust in 3CR radio galaxies: On the FR1-FR2 difference

S. A. H. Mueller·M. Haas·R. Siebenmorgen·U. Klaas·K. Meisenheimer·R. Chini·M. Albrecht
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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.

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S. A. H. Mueller, M. Haas, R. Siebenmorgen, U. Klaas, K. Meisenheimer, R. Chini, M. Albrecht. 2004-09-29. Dust in 3CR radio galaxies: On the FR1-FR2 difference. https://doi.org/10.1051/0004-6361%3A200400067

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