JWST Unveils the Bimodal Nature of Lyα Emitters at 3 z < 7: Pristine versus Merger-driven Populations

Abstract We present a systematic study of merging galaxies among Lyα emitters (LAEs) using James Webb Space Telescope/NIRCam high-resolution imaging data. From a large sample of 817 spectroscopically confirmed LAEs at 3 6 to 45%–50% at z = 3, while the interaction fraction rises from ∼45% at z > 6 to 70% at z log ( M ⋆ M ⊙ ) > 8.5 ) and bright ( M UV 10 8.5 M ⊙ ) systems in which galaxy interactions may enhance star formation and/or facilitate the escape of Lyα photons, or involve mergers with less evolved LAE companions. These findings are consistent with existing observational and theoretical studies, and indicate that galaxy mergers can play an important, though not ubiquitous, role in shaping the evolution and observability of LAEs during the first 2 billion years of cosmic history.