Vikram Khaire, Raghunathan Srianand
We study the effect of H I ionizing photons escaping from the high-z galaxies on the He II ionizing ultraviolet background (UVB) radiation. We show, while these photons do not directly interact with He II ions, they play an important role through radiative transport in modifying the shape of He II ionizing part of UVB spectrum. Within the observed range of UV escape from galaxies, we show the rapid increase in He II Lyman alpha effective optical depth at z ~ 2.7 can be naturally explained without resorting to pre-overlap era of He II reionization. Therefore, a well measured He II Lyman alpha effective optical depth vs z relationship can be used to constrain the redshift evolution of UV escape from high-z galaxies. Our study also stresses the importance of including galaxy contribution even in the fluctuating UV background calculations.
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http://arxiv.org/abs/1211.4579
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