dc.contributor.author Sisk-Reynes, J dc.contributor.author Reynolds, Christopher dc.contributor.author Matthews, James dc.contributor.author Smith, RN dc.date.accessioned 2022-05-17T23:30:23Z dc.date.available 2022-05-17T23:30:23Z dc.date.issued 2022-06-21 dc.identifier.issn 0035-8711 dc.identifier.uri https://www.repository.cam.ac.uk/handle/1810/337257 dc.description.abstract ABSTRACT We present an analysis of deep Chandra Low-Energy and High-Energy Transmission Grating archival observations of the extraordinarily luminous radio-quiet quasar H1821+643, hosted by a rich and massive cool-core cluster at redshift z = 0.3. These data sets provide high-resolution spectra of the AGN at two epochs, free from contamination by the intracluster medium and from the effects of photon pile-up, providing a sensitive probe of the iron-K band. At both epochs, the spectrum is well described by a power-law continuum plus X-ray reflection from both the inner accretion disc and cold, slowly moving distant matter. Adopting this framework, we proceed to examine the properties of the inner disc and the black hole spin. Using Markov chain Monte Carlo (MCMC) methods, we combine constraints from the two epochs assuming that the black hole spin, inner disc inclination, and inner disc iron abundance are invariant. The black hole spin is found to be modest, with a 90 per cent credible range of ${a}^{*}=0.62^{+0.22}_{-0.37}$; and, with a mass MBH in the range log (MBH/M⊙) ∼ 9.2–10.5, this is the most massive black hole candidate for which a well-defined spin constraint has yet been obtained. The modest spin of this black hole supports previous suggestions that the most massive black holes may grow via incoherent or chaotic accretion and/or SMBH-SMBH mergers. dc.description.sponsorship ERC Advanced Award (DISKtoHALO) dc.publisher Oxford University Press (OUP) dc.rights All Rights Reserved dc.rights.uri http://www.rioxx.net/licenses/all-rights-reserved dc.title Evidence for a moderate spin from X-ray reflection of the high-mass supermassive black hole in the cluster-hosted quasar H1821+643 dc.type Article dc.publisher.department Institute of Astronomy dc.date.updated 2022-05-17T07:23:45Z prism.publicationName Monthly Notices of the Royal Astronomical Society dc.identifier.doi 10.17863/CAM.84673 dcterms.dateAccepted 2022-05-12 rioxxterms.versionofrecord 10.1093/mnras/stac1389 rioxxterms.version AM dc.contributor.orcid Sisk-Reynes, J [0000-0003-3814-6796] dc.contributor.orcid Reynolds, Christopher [0000-0002-1510-4860] dc.contributor.orcid Matthews, James [0000-0002-3493-7737] dc.identifier.eissn 1365-2966 rioxxterms.type Journal Article/Review pubs.funder-project-id Science and Technology Facilities Council (ST/S000623/1) pubs.funder-project-id European Commission Horizon 2020 (H2020) ERC (834203) pubs.funder-project-id STFC (ST/V50659X/1) cam.issuedOnline 2022-06-21 cam.orpheus.success Mon Jun 27 07:18:59 BST 2022 - Embargo updated cam.orpheus.counter 4 cam.depositDate 2022-05-17 pubs.licence-identifier apollo-deposit-licence-2-1 pubs.licence-display-name Apollo Repository Deposit Licence Agreement rioxxterms.freetoread.startdate 2022-06-21
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