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dc.contributor.authorGloudemans, A. J.
dc.contributor.authorDuncan, K. J.
dc.contributor.authorRöttgering, H. J. A.
dc.contributor.authorShimwell, T. W.
dc.contributor.authorVenemans, B. P.
dc.contributor.authorBest, P. N.
dc.contributor.authorBrüggen, M.
dc.contributor.authorRivera, G. Calistro
dc.contributor.authorDrabent, A.
dc.contributor.authorHardcastle, M. J.
dc.contributor.authorMiley, G. K.
dc.contributor.authorSchwarz, D. J.
dc.contributor.authorSaxena, A.
dc.contributor.authorSmith, D. J. B.
dc.contributor.authorWilliams, W. L.
dc.date.accessioned2023-10-04T11:00:02Z
dc.date.available2023-10-04T11:00:02Z
dc.date.issued2021-12-31
dc.identifier.citationGloudemans , A J , Duncan , K J , Röttgering , H J A , Shimwell , T W , Venemans , B P , Best , P N , Brüggen , M , Rivera , G C , Drabent , A , Hardcastle , M J , Miley , G K , Schwarz , D J , Saxena , A , Smith , D J B & Williams , W L 2021 , ' Low frequency radio properties of the $z >5$ quasar population ' , Astronomy & Astrophysics , vol. 656 , A137 , pp. 1-11 . https://doi.org/10.1051/0004-6361/202141722
dc.identifier.issn0004-6361
dc.identifier.otherArXiv: http://arxiv.org/abs/2110.06222v1
dc.identifier.otherORCID: /0000-0001-7315-1596/work/143862936
dc.identifier.otherORCID: /0000-0001-9708-253X/work/143863210
dc.identifier.urihttp://hdl.handle.net/2299/26837
dc.description© 2021 ESO. This is the accepted manuscript version of an article which has been published in final form at https://doi.org/10.1051/0004-6361/202141722
dc.description.abstractOptically luminous quasars at z > 5 are important probes of super-massive black hole (SMBH) formation. With new and future radio facilities, the discovery of the brightest low-frequency radio sources in this epoch would be an important new probe of cosmic reionization through 21-cm absorption experiments. In this work, we systematically study the low-frequency radio properties of a sample of 115 known spectroscopically confirmed z > 5 quasars using the second data release of the Low Frequency Array (LOFAR) Two Metre Sky survey (LoTSS-DR2), reaching noise levels of ∼80 µJy beam−1 (at 144 MHz) over an area of ∼ 5720 deg2 . We find that 41 sources (36%) are detected in LoTSS-DR2 at > 2σ significance and we explore the evolution of their radio properties (power, spectral index, and radio loudness) as a function of redshift and rest-frame ultra-violet properties. We obtain a median spectral index of −0.29+0.10 −0.09 by stacking 93 quasars using LoTSS-DR2 and Faint Images of the Radio Sky at Twenty Centimetres (FIRST) data at 1.4 GHz, in line with observations of quasars at z < 3. We compare the radio loudness of the high-z quasar sample to a lower-z quasar sample at z ∼ 2 and find that the two radio loudness distributions are consistent with no evolution, although the low number of high-z quasars means that we cannot rule out weak evolution. Furthermore, we make a first order empirical estimate of the z = 6 quasar radio luminosity function, which is used to derive the expected number of high-z sources that will be detected in the completed LoTSS survey. This work highlights the fact that new deep radio observations can be a valuable tool in selecting high-z quasar candidates for follow-up spectroscopic observations by decreasing contamination of stellar dwarfs and reducing possible selection biases introduced by strict colour cuts.en
dc.format.extent11
dc.format.extent1139403
dc.language.isoeng
dc.relation.ispartofAstronomy & Astrophysics
dc.subjectastro-ph.GA
dc.titleLow frequency radio properties of the $z>5$ quasar populationen
dc.contributor.institutionSchool of Physics, Engineering & Computer Science
dc.contributor.institutionSPECS Deans Group
dc.contributor.institutionDepartment of Physics, Astronomy and Mathematics
dc.contributor.institutionCentre for Astrophysics Research (CAR)
dc.description.statusPeer reviewed
dc.date.embargoedUntil2022-12-15
rioxxterms.versionofrecord10.1051/0004-6361/202141722
rioxxterms.typeJournal Article/Review
herts.preservation.rarelyaccessedtrue


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