Galaxy size evolution with CLAUDS + HSC
Two-wavelength structural analysis of galaxies in COSMOS since z ~ 1.
For my PhD I built a structural-analysis pipeline that fits Sérsic profiles to galaxies in the COSMOS field at two rest-frame wavelengths simultaneously — the rest-frame UV, traced by the deep U-band imaging from CLAUDS (CFHT MegaCam), and the rest-frame optical, traced by the deep grizy imaging from HSC-SSP (Subaru Hyper Suprime-Cam). The pairing is unique: CLAUDS goes ~28th magnitude in U, and HSC matches that depth in five optical filters over the same square degrees.
The science question: when we say a galaxy “grew larger” since z~1, is it because the underlying stellar mass redistributed, or because the wavelength in which we traced light changed as the population aged? The answer matters for every size–mass relation in the literature.
The pipeline I wrote runs GALFIT in parallel on dozens of CPU cores, with custom error characterisation via image simulations. The first paper from this work appeared in MNRAS in 2024 (George et al., 2024).