0 Assigned ID: 7500 ----- Attempting Submission 1 (Thu Apr 16 17:33:50 GMT 2026) ----- HST Phase I Proposal 7500 successfully submitted. Receipt: # 7500-1 ----- Attempting Submission 2 (Thu Apr 16 18:57:59 GMT 2026) ----- HST Phase I Proposal 7500 successfully submitted. Receipt: # 7500-2 ----- Attempting Submission 3 (Thu Apr 16 23:07:22 GMT 2026) ----- At cosmic noon (z=2-3), more than half of star forming galaxies host luminous rest frame UV clumps, the defining morphological signature of this epoch. These clumps form either through gravitational instability in gas rich disks fed by cold accretion, or through galaxy mergers, both channels expected to be enhanced in protoclusters given their elevated gas fractions and higher merger rates than the field. Yet the UV clumpy fraction has never been measured in protocluster environments. We propose the first such measurement, using archival HST F606W imaging (CLUTCH+CANDELS) together with public COSMOS Web JWST rest optical morphologies across 11 spectroscopic protoclusters at 2.2<=z<=2.9 in COSMOS, identified from IGM Ly-alpha tomography technique and spectroscopic overdensities. The uniform sample comprises ~300 members and ~300 field controls at matched depth, PSF, and calibration. Applying Fourier based clump detection to the HST imaging, we measure the UV clumpy fraction as a function of clustercentric radius and local overdensity. Both outcomes are decisive: an enhancement would provide the first detection of environmentally driven clump formation, whereas a null result would establish that internal disk physics governs clump formation independent of environment, despite favorable protocluster conditions. For clumpy galaxies, we then leverage three public JWST rest optical products (Gini/M20, deep learning labels, close pair fractions) to identify whether disk instability or mergers dominate. Together, these measurements constrain the physics of clump formation at a key epoch of galaxy assembly. The resulting clump catalog will be released publicly to the community. Dr. Sattari (PI) is an expert in rest-frame UV galaxy morphology and the environmental dependence of galaxy evolution across cosmic time. She developed the Fourier-based rest-UV clump detection framework used in UVCANDELS (Sattari et al. 2023), which forms the backbone of the analysis proposed here. She has extensive experience reducing and analyzing HST, JWST, and ground-based data across the COSMOS and CANDELS fields, including ongoing JWST/NIRISS work through PASSAGE. The team brings complementary expertise across both arms of the proposal. Dr. Chartab is an expert in identifying large-scale structures and quantifying galaxy properties as a function of environment, with extensive experience in large surveys including LATIS. Drs. Mehta, Nedkova, and Lenkic are experts in clump identification and galaxy morphology: Dr. Mehta has published extensively on giant star-forming clumps from high redshift to the local Universe via Galaxy Zoo: Clump Scout; Dr. Nedkova is an expert in modeling galaxy structure and morphology from multi-wavelength space-based imaging; and Dr. Lenkic has led HST studies of star-forming clumps in gas-rich, turbulent disks. Drs. Teplitz, Colbert, Alavi, and Kim are experts in ultraviolet and optical HST imaging and optimal data-reduction techniques. Dr. Teplitz was PI of UVCANDELS, the definitive UV treasury survey of the CANDELS fields. Dr. Colbert has led HST imaging and slitless-spectroscopy efforts spanning WISP and UVCANDELS. Dr. Alavi has extensive experience with HST UV and optical imaging, including UVCANDELS data reductions and imaging of lensed dwarf galaxies. Dr. Kim has worked extensively with HST UV imaging to study Ly-alpha and Lyman continuum escape from compact, star-forming galaxies. Galaxies 0 false false false false false false false SUPPORTED