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arXiv · 1408.3637

The dust masses of powerful radio galaxies: clues to the triggering of their activity

C. Tadhunter·D. Dicken·R. Morganti·V. Konyves·N. Ysard·N. Nesvadba·C. Ramos Almeida
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Abstract

We use deep Herschel Space Observatory observations of a 90% complete sample of 32 intermediate-redshift 2Jy radio galaxies (0.05 < z < 0.7) to estimate the dust masses of their host galaxies and thereby investigate the triggering mechanisms for their quasar-like AGN. The dust masses derived for the radio galaxies (7.2x10^5 < M_d < 2.6x10^8 M_sun) are intermediate between those of quiescent elliptical galaxies on the one hand, and ultra luminous infrared galaxies (ULIRGs) on the other. Consistent with simple models for the co-evolution of supermassive black holes and their host galaxies, these results suggest that most of the radio galaxies represent the late time re-triggering of AGN activity via mergers between the host giant elliptical galaxies and companion galaxies with relatively low gas masses. However, a minority of the radio galaxies in our sample (~20%) have high, ULIRG-like dust masses, along with evidence for prodigious star formation activity. The latter objects are more likely to have been triggered in major, gas-rich mergers that represent a rapid growth phase for both their host galaxies and their supermassive black holes.

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C. Tadhunter, D. Dicken, R. Morganti, V. Konyves, N. Ysard, N. Nesvadba, C. Ramos Almeida. 2014-08-15. The dust masses of powerful radio galaxies: clues to the triggering of their activity. https://doi.org/10.1093/mnrasl/slu135

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