2026ApJ...997...79U

We present a morphological analysis of Atacama Large Millimeter/submillimeter Array (ALMA) and James Webb Space Telescope (JWST) NIRCam images of nine dusty star-forming galaxies (DSFGs) at z_spec ≈ 3.09, all embedded within the cosmic web filaments at the SSA22 protocluster core. The ALMA 870 μm and 1.1 mm images are obtained at spatial resolutions ranging from 0.5″ to 0.05″ (350 pc at z = 3.09). The high-resolution images enable us to resolve inner structures traced by dust continuum, identifying compact dusty cores, clumps, and offset ridges within bars. Sérsic profile fitting was performed for both ALMA 870 μm and NIRCam F444W images at comparable resolutions (∼0.15″). The Sérsic index measured for 870 μm, masking bright regions, indicates values close to unity, suggesting that dust emission arises from disks with superimposed compact core components. For the JWST F444W images (restframe ∼1μm), the Sérsic indices range between n_F444W ∼ 1-3, pointing to the coexistence of bulges and stellar disks in these DSFGs. A comparison of dust mass surface density, n_F444W, and F200W-F444W color (restframe ∼0.5-1μm) reveals diversity among the DSFGs, likely reflecting different evolutionary stages, including some DSFGs with red cores, indicating ongoing rapid bulge growth phases heavily obscured by dust. The predominantly disklike morphologies observed in most DSFGs in the protocluster core contrast sharply with early-type morphologies that dominate the highest density environment in the local Universe. This suggests that we are witnessing the early formation of the morphology-density relation, as massive galaxies undergo rapid growth as late-type galaxies fueled by cosmic web gas filaments.