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dc.contributor.authorMatsuoka, Ken
dc.contributor.authorNagao, Ten
dc.contributor.authorMarconi, Aen
dc.contributor.authorMaiolino, Robertoen
dc.contributor.authorMannucci, Fen
dc.contributor.authorCresci, Gen
dc.contributor.authorTerao, Ken
dc.contributor.authorIkeda, Hen
dc.date.accessioned2018-11-07T16:35:51Z
dc.date.available2018-11-07T16:35:51Z
dc.date.issued2018-08-01en
dc.identifier.issn0004-6361
dc.identifier.urihttps://www.repository.cam.ac.uk/handle/1810/284722
dc.description.abstractThe mass-metallicity relation (MZR) of type-2 active galactic nuclei (AGNs) at 1.2 < z < 4.0 is investigated by using high-z radio galaxies (HzRGs) and X-ray selected radio-quiet AGNs. We combine new rest-frame ultraviolet (UV) spectra of two radio-quiet type-2 AGNs obtained with FOCAS on the Subaru Telescope with existing rest-frame UV emission lines, i.e., CIV1549, HeII1640, and CIII]1909, of a sample of 16 HzRGs and 6 additional X-ray selected type-2 AGNs, whose host stellar masses have been estimated in literature. We divided our sample in three stellar mass bins and calculated averaged emission-line flux ratios of CIV1549/HeII1640 and CIII]1909/CIV1549. Comparing observed emission-line flux ratios with photoionization model predictions, we estimated narrow line region (NLR) metallicities for each mass bin. We found that there is a positive correlation between NLR metallicities and stellar masses of type-2 AGNs at z ~ 3. This is the first indication that AGN metallicities are related to their hosts, i.e., stellar mass. Since NLR metallicities and stellar masses follow a similar relation as the MZR in star-forming galaxies at similar redshifts, our results indicate that NLR metallicities are related to those of the host galaxies. This study highlights the importance of considering lower-mass X-ray selected AGNs in addition to radio galaxies to explore the metallicity properties of NLRs at high redshift.
dc.description.sponsorshipERC STFC
dc.publisherEDP Sciences
dc.titleThe mass-metallicity relation of high-z type-2 active galactic nucleien
dc.typeArticle
prism.publicationDate2018en
prism.publicationNameAstronomy and Astrophysicsen
prism.volume616en
dc.identifier.doi10.17863/CAM.32094
dcterms.dateAccepted2018-07-24en
rioxxterms.versionofrecord10.1051/0004-6361/201833418en
rioxxterms.versionVoR*
rioxxterms.licenseref.urihttp://www.rioxx.net/licenses/all-rights-reserveden
rioxxterms.licenseref.startdate2018-08-01en
dc.contributor.orcidMaiolino, Roberto [0000-0002-4985-3819]
dc.identifier.eissn1432-0746
rioxxterms.typeJournal Article/Reviewen
pubs.funder-project-idSTFC (ST/M001172/1)
pubs.funder-project-idECH2020 EUROPEAN RESEARCH COUNCIL (ERC) (695671)


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