Journal Article

The escape fraction of ionizing photons from high-redshift galaxies from data-constrained reionization models

Sourav Mitra, Andrea Ferrara and T. Roy Choudhury

in Monthly Notices of the Royal Astronomical Society: Letters

Published on behalf of The Royal Astronomical Society

Volume 428, issue 1, pages L1-L5
Published in print January 2013 |
Published online October 2012 | e-ISSN: 1745-3933 | DOI: http://dx.doi.org/10.1093/mnrasl/sls001

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The escape fraction, fesc, of ionizing photons from high-redshift galaxies is a key parameter to understand cosmic reionization and star formation history. Yet, in spite of many efforts, it remains largely uncertain. We propose a novel, semi-empirical approach based on a simultaneous match of the most recently determined luminosity functions of galaxies in the redshift range 6 ≤ z ≤ 10 with reionization models constrained by a large variety of experimental data. From this procedure, we obtain the evolution of the best-fitting values of fesc along with their 2σ limits. We find that, averaged over the galaxy population, (i) the escape fraction increases from fesc = 0.068+ 0.054− 0.047 at z = 6 to fesc = 0.179+ 0.331− 0.132 at z = 8 and (ii) at z = 10 we can only put a lower limit of fesc > 0.146. Thus, although errors are large, there is an indication of a 2.6 times increase of the average escape fraction from z = 6 to 8, which might partially release the ‘starving reionization’ problem.

Keywords: intergalactic medium; cosmology: theory; dark ages, reionization, first stars; large-scale structure of Universe

Journal Article.  3280 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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