The Lyman-continuum photon production efficiency in the high-redshift
  Universe
  The Lyman Continuum photon production efficiency ($\xi_{\rm ion}$) is a
critical ingredient for inferring the number of photons available to reionise
the intergalactic medium. To estimate the theoretical production efficiency in
the high-redshift Universe we couple the BlueTides cosmological hydrodynamical
simulation with a range of stellar population synthesis models. We find Lyman
Continuum photon production efficiencies of $\log_{10}(\xi_{\rm ion}/{\rm
erg^{-1}\, Hz})\approx 25.1-25.5$ depending on the choice of stellar population
synthesis model. These results are broadly consistent with recent observational
constraints at high-redshift though favour a model incorporating the effects of
binary evolution
