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Arxiv: JWST/MIRI unveils the stellar component of the GN20 dusty galaxy overdensity at z=4.05 Published: 2/28/2024 9:35:28 PM Updated: 2/28/2024 9:35:28 PM

Paper abstract: Despite the importance of the dusty star-forming galaxies (DSFGs) at z>2for understanding the galaxy evolution in the early Universe, their stellardistributions traced by the near-IR emission were spatially unresolved untilthe arrival of the JWST. In this work we present, for the first time, aspatially-resolved morphological analysis of the rest-frame near-IR(~1.1-3.5\mum) emission in DSFGs traced with the JWST/MIRI. In particular, westudy the mature stellar component for the three DSFGs and a Lyman-break galaxy(LBG) present in an overdensity at z=4.05. Moreover, we use MIRI images alongwith UV to (sub)-mm ancillary photometric data to model their SEDs and extracttheir main physical properties. The sub-arcsec resolution MIRI images haverevealed that the stellar component present a wide range of morphologies, fromdisc-like to compact and clump-dominated structures. These near-IR structurescontrast with their UV emission, which is usually diffuse and off-centered. TheSED fitting analysis shows that GN20 dominates the total SFR with a value ~2500M_\odotyr^{-1} while GN20.2b has the highest stellar mass in the sample(M_*~2\times10^{11} M_\odot). The two DSFGs classified as LTGs (GN20and GN20.2a) show high specific SFR (sSFR>30 Gyr^{-1}) placing them above thestar-forming main sequence (SFMS) at z~4 by >0.5 dex while the ETG(i.e.,GN20.2b) is compatible with the high-mass end of the main sequence. Whencomparing with other DSFGs in overdensities at z~2-7 we observe that ourobjects present similar SFRs, depletion times and projected separations.Nevertheless, the effective radii computed for our DSFGs (~3 kpc) are up to twotimes larger than those of isolated galaxies observed in CEERS and ALMA-HUDF atsimilar redshifts. We interpret this difference as an effect of rapid growthinduced by the dense environment.