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dc.contributor.authorGürkan, Gülay
dc.contributor.authorHardcastle, Martin
dc.contributor.authorBest, Philip
dc.contributor.authorMorabito, Leah
dc.contributor.authorPrandoni, Isabella
dc.contributor.authorJarvis, Matt
dc.contributor.authorDuncan, Ken
dc.contributor.authorRivera, Gabriela Calistro
dc.contributor.authorCallingham, Joe
dc.contributor.authorCochrane, Rachel
dc.contributor.authorCroston, Judith
dc.contributor.authorHeald, George
dc.contributor.authorMingo, Beatriz
dc.contributor.authorMooney, Sean
dc.contributor.authorSabater, Jose
dc.contributor.authorRöttgering, Huub
dc.contributor.authorShimwell, Timothy
dc.contributor.authorSmith, Dan
dc.contributor.authorTasse, Cyril
dc.contributor.authorWilliams, Wendy
dc.date.accessioned2019-01-17T16:45:07Z
dc.date.available2019-01-17T16:45:07Z
dc.date.issued2018-10-10
dc.identifier.citationGürkan , G , Hardcastle , M , Best , P , Morabito , L , Prandoni , I , Jarvis , M , Duncan , K , Rivera , G C , Callingham , J , Cochrane , R , Croston , J , Heald , G , Mingo , B , Mooney , S , Sabater , J , Röttgering , H , Shimwell , T , Smith , D , Tasse , C & Williams , W 2018 , ' LoTSS/HETDEX: Optical quasars I. Low-frequency radio properties of optically selected quasars ' , Astronomy & Astrophysics . https://doi.org/10.1051/0004-6361/201833892
dc.identifier.issn0004-6361
dc.identifier.otherPURE: 15717838
dc.identifier.otherPURE UUID: bf3d421e-f5de-41bb-b192-f91db8f3c11d
dc.identifier.otherArXiv: http://arxiv.org/abs/1811.07933v1
dc.identifier.otherScopus: 85062044329
dc.identifier.urihttp://hdl.handle.net/2299/20989
dc.description16 pages, 12 figures, 4 tables. This paper is part of the LOFAR surveys data release 1 and has been accepted for publication in a special edition of A&A that will appear in Feb 2019, volume 622. The catalogues and images from the data release will be publicly available on lofar-surveys.org upon publication of the journal. Reproduced with permission from Astronomy & Astrophysics. © 2018 ESO.
dc.description.abstractThe radio-loud/radio-quiet (RL/RQ) dichotomy in quasars is still an open question. Although it is thought that accretion onto supermassive black holes in the centre the host galaxies of quasars is responsible for some radio continuum emission, there is still a debate as to whether star formation or active galactic nuclei (AGN) activity dominate the radio continuum luminosity. To date, radio emission in quasars has been investigated almost exclusively using high-frequency observations in which the Doppler boosting might have an important effect on the measured radio luminosity, whereas extended structures, best observed at low radio frequencies, are not affected by the Doppler enhancement. We used a sample of quasars selected by their optical spectra in conjunction with sensitive and high-resolution low-frequency radio data provided by the LOw Frequency ARray (LOFAR) as part of the LOFAR Two-Metre Sky Survey (LoTSS) to investigate their radio properties using the radio loudness parameter ($\mathcal{R} = \frac{L_{\mathrm{144-MHz}}}{L_{\mathrm{i\,band}}}$). The examination of the radio continuum emission and RL/RQ dichotomy in quasars exhibits that quasars show a wide continuum of radio properties (i.e. no clear bimodality in the distribution of $\mathcal{R}$). Radio continuum emission at low frequencies in low-luminosity quasars is consistent with being dominated by star formation. We see a significant albeit weak dependency of $\mathcal{R}$ on the source nuclear parameters. For the first time, we are able to resolve radio morphologies of a considerable number of quasars. All these crucial results highlight the impact of the deep and high-resolution low-frequency radio surveys that foreshadow the compelling science cases for the Square Kilometre Array (SKA).en
dc.language.isoeng
dc.relation.ispartofAstronomy & Astrophysics
dc.rightsOpen
dc.subjectastro-ph.GA
dc.titleLoTSS/HETDEX: Optical quasars I. Low-frequency radio properties of optically selected quasarsen
dc.contributor.institutionSchool of Physics, Astronomy and Mathematics
dc.contributor.institutionCentre for Astrophysics Research
dc.description.statusPeer reviewed
dc.relation.schoolSchool of Physics, Astronomy and Mathematics
dc.description.versiontypeFinal Accepted Version
dcterms.dateAccepted2018-10-10
rioxxterms.versionAM
rioxxterms.versionofrecordhttps://doi.org/10.1051/0004-6361/201833892
rioxxterms.licenseref.uriOther
rioxxterms.typeJournal Article/Review
herts.preservation.rarelyaccessedtrue
herts.rights.accesstypeOpen


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