dc.contributor.author Melia, Fulvio dc.contributor.author Fatuzzo, Marco dc.date.accessioned 2016-06-29T19:38:39Z dc.date.available 2016-06-29T19:38:39Z dc.date.issued 2016-01-11 dc.identifier.citation The epoch of reionization in the R h =  ct universe 2016, 456 (4):3422 Monthly Notices of the Royal Astronomical Society en dc.identifier.issn 0035-8711 dc.identifier.issn 1365-2966 dc.identifier.doi 10.1093/mnras/stv2902 dc.identifier.uri http://hdl.handle.net/10150/615094 dc.description.abstract The measured properties of the epoch of reionization (EoR) show that reionization probably began around $z\sim 12-15$ and ended by $z=6$. In addition, a careful analysis of the fluctuations in the cosmic microwave background indicate a scattering optical depth $\tau\sim 0.066\pm0.012$ through the EoR. In the context of $\Lambda$CDM, galaxies at intermediate redshifts and dwarf galaxies at higher redshifts now appear to be the principal sources of UV ionizing radiation, but only for an inferred (ionizing) escape fraction $f_{ion}\sim 0.2$, which is in tension with other observations that suggest a value as small as $\sim 0.05$. In this paper, we examine how reionization might have progressed in the alternative Friedmann-Robertson Walker cosmology known as the $R_{\rm h}=ct$ Universe, and determine the value of $f_{ion}$ required with this different rate of expansion. We find that $R_{\rm h}=ct$ accounts quite well for the currently known properties of the EoR, as long as its fractional baryon density falls within the reasonable range $0.026\lesssim \Omega_b\lesssim 0.037$. This model can also fit the EoR data with $f_{ion}\sim 0.05$, but only if the Lyman continuum photon production is highly efficient and $\Omega_b \sim 0.037$. These results are still preliminary, however, given their reliance on a particular form of the star-formation rate density, which is still uncertain at very high redshifts. It will also be helpful to reconsider the EoR in $R_{\rm h}=ct$ when complete structure formation models become available. dc.language.iso en en dc.publisher OXFORD UNIV PRESS en dc.relation.url http://mnras.oxfordjournals.org/lookup/doi/10.1093/mnras/stv2902 en dc.rights © 2016 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society en dc.title The epoch of reionization in the R h = ct universe en dc.type Article en dc.contributor.department The University of Arizona en dc.identifier.journal Monthly Notices of the Royal Astronomical Society en dc.description.collectioninformation This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu. en dc.eprint.version Final accepted manuscript en refterms.dateFOA 2018-09-11T14:06:43Z html.description.abstract The measured properties of the epoch of reionization (EoR) show that reionization probably began around $z\sim 12-15$ and ended by $z=6$. In addition, a careful analysis of the fluctuations in the cosmic microwave background indicate a scattering optical depth $\tau\sim 0.066\pm0.012$ through the EoR. In the context of $\Lambda$CDM, galaxies at intermediate redshifts and dwarf galaxies at higher redshifts now appear to be the principal sources of UV ionizing radiation, but only for an inferred (ionizing) escape fraction $f_{ion}\sim 0.2$, which is in tension with other observations that suggest a value as small as $\sim 0.05$. In this paper, we examine how reionization might have progressed in the alternative Friedmann-Robertson Walker cosmology known as the $R_{\rm h}=ct$ Universe, and determine the value of $f_{ion}$ required with this different rate of expansion. We find that $R_{\rm h}=ct$ accounts quite well for the currently known properties of the EoR, as long as its fractional baryon density falls within the reasonable range $0.026\lesssim \Omega_b\lesssim 0.037$. This model can also fit the EoR data with $f_{ion}\sim 0.05$, but only if the Lyman continuum photon production is highly efficient and $\Omega_b \sim 0.037$. These results are still preliminary, however, given their reliance on a particular form of the star-formation rate density, which is still uncertain at very high redshifts. It will also be helpful to reconsider the EoR in $R_{\rm h}=ct$ when complete structure formation models become available.
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