Authors: Finkelstein, S. et al (2012)
Summary: In this paper, the contribution of the observed galaxies at redshifts 6, 7 and 8 to the reionisation of the IGM is studied. Taking only the observed galaxy population, an escape fraction of 30% is necessary to sustain reionisation at z=6, while if the luminosity function is integrated down to fainter galaxies, an escape fraction of 10% is sufficient. At redshifts 7 and 8 the observed galaxies do not produce enough ionising photons and fainter galaxies are needed to complete reionisation. The inferred volume ionised fraction from the ionising emissivity of these galaxy populations is consistent with observations of quasar spectra and Lyman-alpha spectroscopy, but inconsistent with the WMAP measurements of the Thomson scattering optical depth.
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