English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

In this first of several application papers, we investigate the mechanics ofreionization from stellar sources in high-z galaxies, the utility of variousclumping factors on estimating the recombination time in the IGM, and thephoton budget required to achieve reionization. We test the accuracy of thestatic and time-dependent models of Madau et al. as predictors of reionizationcompletion/maintenance. We simulate a WMAP7 LCDM cosmological model in a 20 Mpccomoving cube with 800^3 uniform fluid cells and dark matter particles. Bytuning our star formation to approximately match the observed star formationrate density and luminosity function, we created a fully coupledradiation-hydro realization of H reionization which begins to ionize at z~10and completes at z~5.8. We find that roughly 2 ionizing photons per H atom arerequired to convert the neutral IGM to a highly ionized state, which supportsthe "photon starved" scenario discussed by Bolton & Haehnelt. The events duringreionization that lead to this number can generally be described as inside-out,but in reality the narrative depends on the level of ionization of the gas oneattributes to as ionized. We find that the formula for the UV photon productionrate dN/dt_ion(z) needed to maintain the IGM in an ionized state derived byMadau et al. should not be used to predict the epoch of reionization completionbecause it ignores history-dependent terms in the global ionization balancewhich are not ignorable. We find that the time-dependent model for the ionizedvolume fraction Q_HII is more predictive, but overestimates the redshift ofreionization completion by delta_z~1. We propose a revised formulation of thetime-dependent model which agrees with our simulation to O(1%). Finally, we useour simulation to estimate a global UV escape fraction due to circumgalacticgas resolved on our mesh to be <f_esc>~0.7.

Direct Numerical Simulation of Reionization II: Recombinations, Clumping Factors, and the Photon Budget for Reionization