Where and when star formation occurs in main sequence galaxies at cosmic noon

Abstract

We perform spatially resolved pixel-by-pixel Spectral Energy Distribution (SED) fitting on 166 disky star-forming galaxies between 0.7 < z < 3. Due to the incredible spatial resolution of the Near Infrared Camera on board the James Webb Space Telescope, we are able to probe down to ∼0.75 kpc at z=1. From the 2D property maps made from SED fitting with Dense Basis, we extract property radial profiles such as the stellar mass, star formation rate, and dust. We find that massive galaxies above the star-forming main sequence have dusty, star-forming centers, and galaxies below the star-forming main sequence have centrally-depressed star formation, indicating the inside-out growth of galaxies. Additionally, the star formation rate radial profile is not uniformly smooth, but concentrated in star-forming regions. Overall, our results show when galaxies burst above the main sequence, they add new stars in the disk through spatially inhomogeneous star formation, and in their cores through dusty starbursts.