dc.contributor.author Hee, Sonke en dc.contributor.author Vázquez, JA en dc.contributor.author Handley, Will en dc.contributor.author Hobson, Michael en dc.contributor.author Lasenby, Anthony en dc.date.accessioned 2017-04-11T14:52:29Z dc.date.available 2017-04-11T14:52:29Z dc.date.issued 2017-04-01 en dc.identifier.issn 0035-8711 dc.identifier.uri https://www.repository.cam.ac.uk/handle/1810/263603 dc.description.abstract Data-driven model-independent reconstructions of the dark energy equation of state $w$($z$) are presented using $\textit{Planck}$ 2015 era cosmic microwave background, baryonic acoustic oscillations (BAO), Type Ia supernova (SNIa) and Lyman $\alpha$ (Ly$\alpha$) data. These reconstructions identify the $w$($z$) behaviour supported by the data and show a bifurcation of the equation of state posterior in the range 1.5 < $z$ < 3. Although the concordance $\Lambda$ cold dark matter ($\Lambda$CDM) model is consistent with the data at all redshifts in one of the bifurcated spaces, in the other, a supernegative equation of state (also known as ‘phantom dark energy’) is identified within the 1.5$\sigma$ confidence intervals of the posterior distribution. To identify the power of different data sets in constraining the dark energy equation of state, we use a novel formulation of the Kullback–Leibler divergence. This formalism quantifies the information the data add when moving from priors to posteriors for each possible data set combination. The SNIa and BAO data sets are shown to provide much more constraining power in comparison to the Ly$\alpha$ data sets. Further, SNIa and BAO constrain most strongly around redshift range 0.1–0.5, whilst the Ly$\alpha$ data constrain weakly over a broader range. We do not attribute the supernegative favouring to any particular data set, and note that the $\Lambda$CDM model was favoured at more than 2 log-units in Bayes factors over all the models tested despite the weakly preferred $w$($z$) structure in the data. dc.description.sponsorship This work was performed using the Darwin Supercomputer 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 (STFC). Parts of this work were undertaken on the COSMOS Shared Memory system at DAMTP, University of Cambridge operated on behalf of the STFC DiRAC HPC Facility; this equipment is funded by BIS National E-infrastructure capital grant ST/J005673/1 and STFC grants ST/H008586/1, ST/K00333X/1. SH and WJH thank STFC for fi- nancial support. dc.language.iso en en dc.publisher Oxford University Press dc.subject equation of state en dc.subject methods: data analysis en dc.subject methods: statistical en dc.subject cosmological parameters en dc.subject dark energy en dc.title Constraining the dark energy equation of state using Bayes theorem and the Kullback–Leibler divergence en dc.type Article prism.endingPage 377 prism.issueIdentifier 1 en prism.publicationDate 2017 en prism.publicationName Monthly Notices of the Royal Astronomical Society en prism.startingPage 369 prism.volume 466 en dc.identifier.doi 10.17863/CAM.8956 dcterms.dateAccepted 2016-11-28 en rioxxterms.versionofrecord 10.1093/mnras/stw3102 en rioxxterms.version VoR en rioxxterms.licenseref.uri http://www.rioxx.net/licenses/all-rights-reserved en rioxxterms.licenseref.startdate 2017-04-01 en dc.contributor.orcid Handley, Will [0000-0002-5866-0445] dc.contributor.orcid Lasenby, Anthony [0000-0002-8208-6332] dc.identifier.eissn 1365-2966 rioxxterms.type Journal Article/Review en pubs.funder-project-id STFC (ST/J005673/1) pubs.funder-project-id STFC (ST/K00333X/1) pubs.funder-project-id STFC (ST/M00418X/1) pubs.funder-project-id STFC (ST/M007065/1) pubs.funder-project-id STFC (1208121) pubs.funder-project-id STFC (ST/L000636/1) pubs.funder-project-id STFC (ST/H008586/1) pubs.funder-project-id STFC (ST/P000673/1) pubs.funder-project-id STFC (ST/M001172/1) cam.issuedOnline 2016-12-01 en cam.orpheus.success Thu Jan 30 12:56:32 GMT 2020 - The item has an open VoR version. * rioxxterms.freetoread.startdate 2100-01-01
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