Early Results from GLASS-JWST XXII: Rest frame UV-optical spectral properties of Lyman-alpha emitting galaxies at 3 $<$ z $<$ 6

Abstract

Ly$\hat{I}\pm$ emission is possibly the best indirect diagnostic of Lyman continuum (LyC) escape since the conditions that favor the escape of Ly$\hat{I}\pm$ photons are often the same that allows for the escape of LyC photons. In this work, we present the rest UV-optical spectral characteristics of 11 Ly$\hat{I}\pm$ emitting galaxies at 3 $<$ z $<$ 6 - the optimal redshift range chosen to avoid the extreme IGM attenuation while simultaneously studying galaxies close enough to the epoch of reionization. From a combined analysis of JWST/NIRSpec and MUSE data, we present the Ly$\hat{I}\pm$ escape fraction and study their correlations with other physical properties of galaxies that might facilitate Ly$\hat{I}\pm$ escape. We find that our galaxies have low masses (80\% of the sample with $\mathrm{lo}{\mathrm{g}}_{10}{\mathrm{M}}_{\star }<9.5{\mathrm{M}}_{\odot }$), compact sizes (median ${\mathrm{R}}_{\mathrm{e}}\sim 0.7\mathrm{kpc}$), low dust content, moderate [OIII]/[OII] flux ratios (mean $\sim$ 6.8 $\pm$ 1.2), and moderate Ly$\hat{I}\pm$ escape fraction (mean ${\mathrm{f}}_{\mathrm{esc}}^{\mathrm{Ly}\hat{\mathrm{I}}\pm }\sim$ 0.11). Our sample show characteristics that are broadly consistent with the low redshift galaxies with Ly$\hat{I}\pm$ emission, which are termed as "analogs" of high redshift population. We predict the Lyman continuum escape fraction in our sample to be low (0.03-0.07), although larger samples in the post-reionization epoch are needed to confirm these trends.

15 pages, 4 figures, 1 table; Submitted to ApJL