Inferring the IGM Neutral Fraction at z ~ 6-8 with Low-Luminosity Lyman Break Galaxies

Understand

We present a Bayesian inference on the neutral hydrogen fraction of the intergalactic medium (IGM), $x_{\textrm{HI}}$, at $z \sim$ 6-8 using the properties of Lyman break galaxies during the Epoch of Reionization.

• We use large samples of LBG candidates at $5.5 \leq z \leq 8.2$ with spectroscopy from Keck/DEIMOS and Keck/MOSFIRE.
• For each galaxy, we incorporate either the Lyman-$\alpha$ equivalent width (EW) for detections or the EW limit spectrum for nondetections to parameterize the EW distribution at various ultraviolet brightnesses for a given redshift.
• Using our reference sample of galaxy candidates from the ionized universe at $z$ $\sim$ 6.0, we are able to infer $x_{\textrm{HI}}$ at two redshifts: $z$ $\sim$ 6.7 and $z$ $\sim$ 7.6.