Early Results from GLASS-JWST. XXII. Rest-frame UV–Optical Spectral Properties of Lyα Emitting Galaxies at 3 < z < 6

Abstract

Abstract Lyα emission is possibly the best indirect diagnostic of Lyman continuum (LyC) escape since the conditions that favor the escape of Lyα photons are often the same that allow for the escape of LyC photons. In this work, we present the rest-frame UV–optical spectral characteristics of 11 Lyα emitting galaxies at 3 < z < 6—the redshift range that optimizes between intergalactic medium attenuation effects and temporal proximity to the epoch of reionization. From a combined analysis of JWST/NIRSpec and MUSE data, we present the Lyα escape fraction and study its correlation with other physical properties of galaxies that might facilitate Lyα escape. We find that our galaxies have low masses (80% of the sample with log 10 M ⋆ < 9.5 M ⊙ ), compact sizes (median R e ∼ 0.7 kpc), low dust content, moderate [O iii]/[O ii] flux ratios (mean ∼ 6.8 ± 1.2), and moderate Lyα escape fractions (mean f esc Ly α ∼ 0.11). Our sample shows characteristics that are broadly consistent with low-redshift galaxies with Lyα emission, which are termed as “analogs” of the high-redshift population. We predict the LyC escape fraction in our sample to be low (0.03–0.07), although larger samples in the postreionization epoch are needed to confirm these trends.