Publisher
OXFORD UNIV PRESSCitation
The epoch of reionization in the R h = ct universe 2016, 456 (4):3422 Monthly Notices of the Royal Astronomical SocietyRights
© 2016 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society.Collection Information
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.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.ISSN
0035-87111365-2966
Version
Final accepted manuscriptAdditional Links
http://mnras.oxfordjournals.org/lookup/doi/10.1093/mnras/stv2902ae974a485f413a2113503eed53cd6c53
10.1093/mnras/stv2902