The JWST Unveils the Bimodal Nature of Lyman Alpha Emitters at 3 <z<7: Pristine versus Merger-Driven Populations

We present a systematic study of merging galaxies among Lyman-alpha emitters (LAEs) using JWST/NIRCam high-resolution imaging data. From a large sample of 817 spectroscopically confirmed LAEs at $3<z<7$ in the GOODS-S field, we identify late-stage mergers and interacting systems with fractions of 39.4%±2.5% and 60.6%±6.3%, respectively. These fractions exhibit significant redshift evolution and depend on both stellar mass (M_*) and UV magnitude (MUV), being most prevalent in massive (log(M_*/M₎>8.5) and bright (MUV<-19.5) systems. At fixed M_* and MUV, we find negligible differences in the UV slope ($β$) between late-stage mergers and isolated LAEs; however, a clear bimodal distribution emerges in the M_*-sSFR plane, where isolated LAEs peak at log(M_*/M₎≈7.8 and log( sSFR/yr⁻¹)≈-7.4, and late-stage mergers peak at log(M_*/M₎≈8.6 and log( sSFR/yr⁻¹)≈-7.6. Our results reveal two evolutionary classes -- Pristine LAEs, low-mass (M_*<108.5M_), isolated systems that represent early-stage galaxies with minimal merger interactions, and Merger-driven LAEs, massive (M_*>108.5M_) systems in which mergers enhance star formation and facilitate the escape of Lyman-alpha photons or accrete pristine LAEs -- both of which are consistent with both observational and theoretical expectations and collectively demonstrate that mergers are a central driver of LAE evolution across the first two billion years.