The cluster environments of powerful radio-loud and radio-quiet active galactic nuclei |
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| Authors: | R J McLure J S Dunlop |
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| Institution: | Nuclear and Astrophysics Laboratory, University of Oxford, Keble Road, Oxford OX1 3RH;Institute for Astronomy, University of Edinburgh, Blackford Hill, Edinburgh 3H9 3HJ |
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| Abstract: | The spatial clustering amplitude ( B gq) is determined for a sample of 44 powerful active galactic nuclei (AGN) at z ≃0.2. No significant difference is detected in the richness of the cluster environments of the radio-loud and radio-quiet subsamples, both of which typically inhabit environments as rich as Abell class ≃0. Comparison with radio luminosity-matched samples from Hill & Lilly and Wold et al. suggests that there is no epoch-dependent change in environment richness out to at least z ≥0.5 for either radio galaxies or radio quasars. Comparison with the APM cluster survey shows that, contrary to current folklore, powerful AGN do not avoid rich clusters, but rather display a spread in cluster environment, which is perfectly consistent with being drawn at random from the massive elliptical population. Finally, we argue that virtually all Abell class ≃0 clusters contained an active galaxy during the epoch of peak quasar activity at z ∼2.5. |
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| Keywords: | galaxies: active galaxies: clusters: general quasars: general |
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