The Universe is at Most 88% Neutral at z=10.6
astro-ph.GA
/ Authors
/ Abstract
Recent observations of GN-z11 with JWST have revealed a Ly$α$ emission line with an equivalent width of 18$\pm 2$ angstroms. At z=10.6, this galaxy is expected to lie in the heart of reionization. We use a series of inhomogeneous reionization simulations to derive the distribution of the Ly$α$ EW after traveling through the neutral intergalactic medium with varying average neutral gas fraction, $x_{HI}$. We use these distribution to place an upper limit of $x_{HI} < $ 0.88 at z=10.6 at 95% confidence level. We compare our upper limit to different reionization history models, which include the recently identified enhancement at the bright end of the luminosity function at z>8. We find that models in which faint galaxies have higher escape fraction compared to bright galaxies are favored by the new data.