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dc.contributor.authorChardin, Jonathanen
dc.contributor.authorPuchwein, Ewalden
dc.contributor.authorHaehnelt, Martinen
dc.date.accessioned2017-03-28T12:35:59Z
dc.date.available2017-03-28T12:35:59Z
dc.date.issued2017-03-01en
dc.identifier.issn0035-8711
dc.identifier.urihttps://www.repository.cam.ac.uk/handle/1810/263280
dc.description.abstractLy$\alpha$ forest data probing the post-reionization Universe show surprisingly large opacity fluctuations over rather large (≥50 $h^{−1}$ comoving Mpc) spatial scales. We model these fluctuations using a hybrid approach utilizing the large-volume Millennium simulation to predict the spatial distribution of QSOs combined with smaller scale full hydrodynamical simulation performed with $\small \text{RAMSES}$ and post-processed with the radiative transfer code $\small \text{ATON}$. We produce realistic mock absorption spectra that account for the contribution of galaxies and QSOs to the ionizing UV background. These improved models confirm our earlier findings that a significant ($\gtrsim$50 per cent) contribution of ionizing photons from QSOs can explain the large reported opacity fluctuations on large scales. The inferred QSO luminosity function is thereby consistent with recent estimates of the space density of QSOs at this redshift. Our simulations still somewhat struggle, however, to reproduce the very long (110 $h^{−1}$ comoving Mpc) high-opacity absorption through observed in ULAS J0148+0600, perhaps suggesting an even later end of reionization than assumed in our previously favoured model. Medium-deep/medium area QSO surveys as well as targeted searches for the predicted strong transverse QSO proximity effect would illuminate the origin of the observed large-scale opacity fluctuations. They would allow us to substantiate whether UV fluctuations due to QSO are indeed primarily responsible, or whether significant contributions from other recently proposed mechanisms such as large-scale fluctuations in temperature and mean free path (even in the absence of rare bright sources) are required.
dc.description.sponsorshipThis work was supported by the ERC Advanced Grant 320596 ‘The Emergence of Structure during the epoch of Reionization’. This work was performed using the COSMOS and Darwin Supercomputers of the University of Cambridge High Performance Computing Service (http://www.hpc.cam.ac.uk/), provided by Dell Inc. using Strategic Research Infrastructure Funding from the Higher Education Funding Council for England and funding from the Science and Technology Facilities Council. This work furthermore used the Wilkes GPU cluster at the University of Cambridge High Performance Computing Service (http://www.hpc.cam.ac.uk/), provided by Dell Inc., NVIDIA and Mellanox, and part funded by STFC with industrial sponsorship from Rolls Royce and Mitsubishi Heavy Industries. Some of the hydrodynamical simulations used in this work were performed with supercomputer time awarded by the Partnership for Advanced Computing in Europe (PRACE) 8th Call. We acknowledge PRACE for enabling access to the Curie supercomputer, based in France at the Tres Grand Centre de Calcul (TGCC). EP acknowledges support by ` the Kavli foundation. The research of JC and MH was supported by the Munich Institute for Astro- and Particle Physics (MIAPP) of the DFG cluster of excellence ‘Origin and Structure of the Universe’.
dc.language.isoenen
dc.publisherOxford University Press
dc.subjectmethods: numericalen
dc.subjectgalaxies: evolutionen
dc.subjectquasars: generalen
dc.subjectcosmology: theoryen
dc.subjectdiffuse radiationen
dc.titleLarge-scale opacity fluctuations in the Ly$\alpha$ forest: evidence for QSOs dominating the ionizing UV background at $z$ ~ 5.5–6?en
dc.typeArticle
prism.endingPage3445
prism.issueIdentifier3en
prism.publicationDate2017en
prism.publicationNameMonthly Notices of the Royal Astronomical Societyen
prism.startingPage3429
prism.volume465en
dc.identifier.doi10.17863/CAM.8602
dcterms.dateAccepted2016-11-11en
rioxxterms.versionofrecord10.1093/mnras/stw2943en
rioxxterms.versionVoRen
rioxxterms.licenseref.urihttp://www.rioxx.net/licenses/all-rights-reserveden
rioxxterms.licenseref.startdate2017-03-01en
dc.contributor.orcidHaehnelt, Martin [0000-0001-8443-2393]
dc.identifier.eissn1365-2966
dc.publisher.urlhttp://dx.doi.org/10.1093/mnras/stw2943en
rioxxterms.typeJournal Article/Reviewen
pubs.funder-project-idSCIENCE & TECHNOLOGY FACILITIES COUNCIL (ST/N000927/1)
pubs.funder-project-idSTFC (ST/J005673/1)
pubs.funder-project-idSTFC (ST/K00333X/1)
pubs.funder-project-idSTFC (ST/M007065/1)
pubs.funder-project-idEuropean Research Council (320596)
pubs.funder-project-idSTFC (ST/P000673/1)
pubs.funder-project-idSTFC (ST/L000636/1)
cam.issuedOnline2016-11-17en
cam.orpheus.successThu Jan 30 12:53:33 GMT 2020 - The item has an open VoR version.*
rioxxterms.freetoread.startdate2100-01-01


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