Rest-Frame UV and Optical Structural Evolution of Narrowband-Selected Lyman-alpha Emitters at z = 2-7 with JWST/NIRCam

We present a systematic study of the rest-frame ultraviolet (UV) and optical morphologies of Ly α emitters (LAEs) at z 2 - 7 from the SILVERRUSH multi-narrowband catalog, using JWST/NIRCam imaging from COSMOS-Web. We fit Sérsic profiles in four NIRCam filters (F115W, F150W, F277W, F444W) for LAEs spanning about 2.2 Gyr of cosmic time. LAE sizes show a mild increase from rest-frame UV to optical wavelengths, with a median optical-to-UV size ratio of R e, opt/R e, UV = 1.14+0.01-0.02, indicating a small morphological K-correction; this offset is significant at z at most 5.7 but not at z = 6.6. The rest-frame optical sizes follow a power-law evolution, given by R e proportional to (1+z)-0.94 plus or minus 0.09, decreasing from 0.91+0.07-0.07 kpc at z = 2.2 to about 0.5 kpc at z 5, in close agreement with a recent JWST study of spectroscopically confirmed LAEs. The rest-frame optical size-mass relation slopes are broadly consistent with those of the general star-forming galaxy (SFG) population, while LAEs lie below it in normalization over z about 3 - 6. More compact LAEs tend to exhibit higher Ly α equivalent widths, a trend driven mainly by the most compact, marginally resolved sources. These compact systems also occupy elevated SFR surface-density regimes, consistent with a scenario in which concentrated star formation may facilitate Ly α escape. No significant correlation of LAE rest-frame optical size with projected large-scale environment is found over z 2 - 7, suggesting that LAE morphology may be governed primarily by internal galaxy properties, except possibly in the most extreme overdensities.