Probing Patchy Reionization with the Void Probability Function in the era of RST

<p>Neutral hydrogen attenuates the Lyman-alpha emission of galaxies, dimming and increasing the apparent clustering of Lyman-Alpha Emitters (LAEs). LAEs are more likely to be observed in the regions that have already been ionized, so LAEs within more neutral intergalactic medium appear more clustered. Using the Jensen et al 2014 simulations of LAEs at various ionization fractions, we show how the Void Probability Function (VPF) measures the clustering signals caused by an increasingly neutral intergalactic medium. The VPF is sensitive to voids and can be easily compared for samples of the same number density, and therefore might be the best option for teasing out the particular clustering caused by &#39;inside-out&#39; patchy reionization. We simulate what ionization fractions constraints the Lyman Alpha Galaxies in the Epoch of Reionization (LAGER) survey can give with the VPF, and motivate the use of the VPF for reionization surveys with WFIRST.</p>