Intergalactic Lyman-α haloes before reionization are detectable with JWST

Abstract

The James Webb Space Telescope (JWST) recently reported a large population of UV luminous galaxies at high redshifts, z > 10, as well as Lyman-α emitting (LAE) galaxies out to z ∼ 11. We use the observed UV luminosities along with a data-driven approach at lower redshifts to place constraints on the observability of the intergalactic Lyman-α intensity, scattered in the form of Loeb-Rybicki haloes, during the pre-reionization and reionization epochs (z ∼ 9-16). We forecast the sensitivity and resolution required to detect these intergalactic haloes, finding that individual haloes with LAE luminosities > 1043 ergs/s are detectable at a few sigma level at z ≲ 9, while stacking of ∼ 10 haloes is expected to result in detections out to z ∼ 16. Finding these haloes is expected to shed light on the neutral intergalactic hydrogen during cosmic reionization.