Alexander de la Vega, Bahram Mobasher, Zahra Sattari, Nima Chartab, Faezeh Manesh, Niloofar Sharei
Abstract High-redshift galaxies exhibit compact regions of intense star formation, known as “clumps,” which are conspicuous in the rest-frame ultraviolet. Studying them can shed light on how they form and evolve and inform theoretical models of galaxy evolution. We examine the evolution of clumpy galaxies with redshift and stellar mass over 2 < z < 9 with James Webb Space Telescope (JWST) imaging from the JWST Advanced Extragalactic Survey. Off-center clumps are detected in the rest-frame near-ultraviolet using similar techniques to those in earlier studies based on Hubble Space Telescope (HST) images. This is done for a sample of 9121 star-forming galaxies with stellar masses log M ⋆ / M ⊙ ≥ 8 . The fraction of clumpy galaxies, f clumpy , increases from ∼10% at z ∼ 7.75 to ∼70% at z ∼ 2.75 at log M ⋆ / M ⊙ ≥ 9 . Our f clumpy values are generally higher at fixed redshift and increase faster with decreasing redshift than what studies based on HST data found, which we attribute largely to the higher sensitivity of JWST. f clumpy correlates with stellar mass. Our f clumpy measurements are compared with those from simulations as well as other observations. At low redshifts ( z ≲ 5.75) and intermediate-to-high stellar masses ( log M ⋆ / M ⊙ ≥ 9 ), our results suggest gas fragmentation due to violent disk instabilities to be the dominant mechanism for forming clumps. At high redshifts and intermediate stellar masses, compression of gas during mergers appears to dominate.