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dc.contributor.authorEvans, D.A.
dc.contributor.authorHardcastle, M.J.
dc.contributor.authorCroston, J.H.
dc.date.accessioned2008-06-27T14:12:25Z
dc.date.available2008-06-27T14:12:25Z
dc.date.issued2008
dc.identifier.citationEvans , D A , Hardcastle , M J & Croston , J H 2008 , X-Ray Nuclei in Radio Galaxies: Exploring the Roles of Hot and Cold Gas Accretion . in In: Extragalactic Jets: Theory and Observation from Radio to Gamma Ray - ASP Conf Series 386 . Astronomical Society of the Pacific , pp. 161-168 .
dc.identifier.isbn978-1-58381-336-2
dc.identifier.isbn978-1-58381-335-5
dc.identifier.otherPURE: 144041
dc.identifier.otherPURE UUID: 7f7dc161-ad2d-4901-a82f-ee6873de666c
dc.identifier.otherdspace: 2299/2136
dc.identifier.urihttp://hdl.handle.net/2299/2136
dc.descriptionOriginal paper can be found at: http://www.astrosociety.org/pubs/cs/381.html Copyright ASP
dc.description.abstractWe present results from Chandra and XMM-Newton spectroscopic observations of the nuclei of z < 0.5 radio galaxies and quasars from the 3CRR catalog, and examine in detail the dichotomy in the properties of low- and high-excitation radio galaxies. The X-ray spectra of low-excitation sources (those with weak or absent optical emission lines) are dominated by unabsorbed emission from a parsec-scale jet, with no contribution from accretion-related emission. These sources show no evidence for an obscuring torus, and are likely to accrete in a radiatively inefficient manner. High-excitation sources (those with prominent optical emission lines), on the other hand, show a significant contribution from a radiatively efficient accretion disk, which is heavily absorbed in the X-ray when they are oriented close to edge-on with respect to the observer. However, the low-excitation/high-excitation division does not correspond to the FRI/FRII division: thus the Fanaroff-Riley dichotomy remains a consequence of the interaction between the jet and the hot-gas environment through which it propagates. Finally, we suggest that accretion of the hot phase of the IGM is sufficient to power all low-excitation radio sources, while high-excitation sources require an additional contribution from cold gas that in turn forms the cold disk and torus. This model explains a number of properties of the radio-loud active galaxy population, and has important implications for AGN feedback mechanisms.en
dc.language.isoeng
dc.publisherAstronomical Society of the Pacific
dc.relation.ispartofIn: Extragalactic Jets: Theory and Observation from Radio to Gamma Ray - ASP Conf Series 386
dc.titleX-Ray Nuclei in Radio Galaxies: Exploring the Roles of Hot and Cold Gas Accretionen
dc.contributor.institutionSchool of Physics, Astronomy and Mathematics
rioxxterms.typeOther
herts.preservation.rarelyaccessedtrue


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