Are luminous radio-loud active galactic nuclei triggered by galaxy interactions?



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Ramos Almeida, C. and Bessiere, P. S. and Tadhunter, C. N. and Pérez González, Pablo Guillermo and Barro, G. and Inskip, K. J. and Morganti, R. and Holt, J. and Dicken, D. (2012) Are luminous radio-loud active galactic nuclei triggered by galaxy interactions? Monthly notices of the Royal Astronomical Society, 419 (1). pp. 687-705. ISSN 0035-8711

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We present the results of a comparison between the optical morphologies of a complete sample of 46 southern 2 Jy radio galaxies at intermediate redshifts (0.05 < z < 0.7) and those of two control samples of quiescent early-type galaxies: 55 ellipticals at redshifts z ≤ 0.01 from the Observations of Bright Ellipticals at Yale (OBEY) survey, and 107 early-type galaxies at redshifts 0.2 < z < 0.7 in the Extended Groth Strip (EGS). Based on these comparisons, we discuss the role of galaxy interactions in the triggering of powerful radio galaxies (PRGs). We find that a significant fraction of quiescent ellipticals at low and intermediate redshifts show evidence for disturbed morphologies at relatively high surface brightness levels, which are likely the result of past or on-going galaxy interactions. However, the morphological features detected in the galaxy hosts of the PRGs (e.g. tidal tails, shells, bridges, etc.) are up to 2 mag brighter than those present in their quiescent counterparts. Indeed, if we consider the same surface brightness limits, the fraction of disturbed morphologies is considerably smaller in the quiescent population (53 per cent at z < 0.2 and 48 per cent at 0.2 ≤ z < 0.7) than in the PRGs (93 per cent at z < 0.2 and 95 per cent at 0.2 ≤ z < 0.7 considering strong-line radio galaxies only). This supports a scenario in which PRGs represent a fleeting active phase of a subset of the elliptical galaxies that have recently undergone mergers/interactions. However, we demonstrate that only a small proportion (≲20 per cent) of disturbed early-type galaxies are capable of hosting powerful radio sources.

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© 2011 The Authors.
© 201Monthly Notices of the Royal Astronomical Society.
© 2011 RAS.
CRA acknowledges financial support from STFC PDRA (ST/G001758/1). CRA, PGPG and GB acknowledge the Spanish Ministry of Science and Innovation (MICINN) through project Consolider-Ingenio 2010 Program grant CSD2006-00070: First Science with the GTC ( PGPG and GB acknowledge support from the Spanish Programa Nacional de Astronomía y Astrofísica under grants AYA2009-10368 and AYA2009-07723-E. KJI is supported through the Emmy Noether programme of the German Science Foundation (DFG). This work has made use of the Rainbow Cosmological Surveys Data base, which is operated by the Universidad Complutense de Madrid (UCM). This work is based in part on data collected at Subaru Telescope, which is operated by the National Astronomical Observatory of Japan. This research has made use of the NED which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. The authors specially acknowledge Tomer Tal for providing access to the OBEY images, as well as David Carter, Richard Pogge, Philip Massey, Giovanni Carraro and Carlos López SanJuan for their valuable help. We finally acknowledge useful comments from the anonymous referee.

Uncontrolled Keywords:Supermassive black-holes; Similar-to 1; Brightest cluster galaxies; Merger-AGN connection; Cooling-flow clusters; Elliptic galaxies; Host galaxies; Star-formation; Cosmological framework; Velocity dispersion
Subjects:Sciences > Physics > Astrophysics
Sciences > Physics > Astronomy
ID Code:38516
Deposited On:21 Jul 2016 14:40
Last Modified:10 Dec 2018 15:05

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