The fraction of clumpy star-forming galaxies in nearby galaxies from CLAUDS and HSC-SSP

Massive, star-forming clumps are regions of intensive star-formation that are commonly observed in high-redshift (z > 1) galaxies. Observations of low-redshift clumpy galaxy analogues are rare but the availability of wide-field galaxy survey data makes the detection of large clumpy galaxy samples much more feasible. We present a population of 12,790 star-forming clumps detected in a mass-complete sample of 5,395 star-forming galaxies (SFGs) at redshifts z at most0.32, located in the XMM-LSS, E-COSMOS and DEEP2-3 fields observed by the Hyper Suprime-Cam Subaru Strategic Survey (HSC-SSP) and CFHT Large Area U-band Deep Survey (CLAUDS). The clumps were detected using an improved version of our Deep Learning (DL)-based object detection framework which uses the ZOOBOT foundation DL-model as a 'backbone' feature extractor. We determined the fraction of star-forming galaxies hosting at least one off-centre clump (f clumpy) based on a clump definition that requires a clump-galaxy flux ratio in the CLAUDS u-band of at least8%. We estimate f clumpy to decrease from about 31% at z about0.3 to about 23% at z about 0.1, which aligns well with a low-redshift extrapolation of the clumpy fraction that is measured using high-redshift observations. At fixed redshift, f clumpy is negatively correlated with the stellar mass and positively correlated with the specific star-formation rate (sSFR) of the host galaxies. When the clump definition is changed to include only clumps with a stellar mass of M cl at least 10 7 M, we observe a highly increased clumpy fraction of about 60% that tends to increase with the stellar mass of the host galaxies but does not show a dependence on the sSFR of the host galaxies.