Abstract
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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