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dc.contributor.authorRigby, E.E.
dc.contributor.authorArgyle, Joshua
dc.contributor.authorBest, P.N.
dc.contributor.authorRosario, D.
dc.contributor.authorRöttgering, H.J.A.
dc.identifier.citationRigby , E E , Argyle , J , Best , P N , Rosario , D & Röttgering , H J A 2015 , ' Cosmic downsizing of powerful radio galaxies to low radio luminosities ' Astronomy & Astrophysics , vol. 581 , A96 . DOI: 10.1051/0004-6361/201526475en
dc.identifier.otherPURE: 222605491
dc.identifier.otherPURE UUID: c4dc52a7-548a-4cf3-bf17-b7f9bbf1c67f
dc.identifier.otherScopus: 84941365103
dc.descriptionE.E.R. acknowledges financial support from NWO (grant number: NWO-TOP LOFAR 614.001.006). E.E.R. and J.A. thank the Leiden/ESA astrophysics program for summer students (LEAPS) which supported J.A. in Leiden.en
dc.description.abstractAims. At bright radio powers (P1.4 GHz > 1025 W/Hz) the space density of the most powerful sources peaks at higher redshift than that of their weaker counterparts. This paper establishes whether this luminosity-dependent evolution persists for sources an order of magnitude fainter than those previously studied, by measuring the steep-spectrum radio luminosity function (RLF) across the range 1024 < P1.4 GHz < 1028 W/Hz, out to high redshift. Methods. A grid-based modelling method is used in which no assumptions are made about the RLF shape and high-redshift behaviour. The inputs to the model are the same as in previous works: redshift distributions from radio source samples, together with source counts and determinations of the local luminosity function. However, to improve coverage of the radio power vs. redshift plane at the lowest radio powers, a new faint radio sample is introduced; it covers an area of 0.8 sq. deg., in the Subaru/XMM-Newton Deep Field, to a 1.4 GHz flux density limit of S1.4 GHz ≥ 100 μJy, with 99% redshift completeness. Results. The modelling results show that the previously seen high-redshift declines in space density persist to P1.4 GHz < 1025 W/Hz. At P1.4 GHz > 1026 W/Hz the redshift of the peak space density increases with luminosity, whilst at lower radio luminosities the position of the peak remains constant within the uncertainties. This cosmic downsizing behaviour is found to be similar to that seen at optical wavelengths for quasars, and is interpreted as representing the transition from radiatively efficient to inefficient accretion modes in the steep-spectrum population. This conclusion is supported by constructing simple models for the space density evolution of these two different radio galaxy classes; these models are able to successfully reproduce the observed variation in peak redshift.en
dc.relation.ispartofAstronomy & Astrophysicsen
dc.rightsCopyright ESO 2015. Reproduced with permission from Astronomy & Astrophysics, © ESO. This is the final published version of the work, which was originally published at
dc.subjectGalaxies: activeen
dc.subjectGalaxies: high-redshiften
dc.subjectGalaxies: evolutionen
dc.subjectQB Astronomyen
dc.subjectQC Physicsen
dc.titleCosmic downsizing of powerful radio galaxies to low radio luminositiesen
dc.typeJournal articleen
dc.description.versionPublisher PDFen
dc.contributor.institutionUniversity of St Andrews. School of Physics and Astronomyen
dc.description.statusPeer revieweden

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