MIDIS: JWST/MIRI Reveals the Stellar Structure of ALMA-selected Galaxies in the Hubble Ultra Deep Field at Cosmic Noon

• Published in: The Astrophysical journal Vol. 969; no. 1; pp. 27 - 45
• Main Authors: Boogaard, Leindert A., Gillman, Steven, Melinder, Jens, Walter, Fabian, Colina, Luis, Östlin, Göran, Caputi, Karina I., Iani, Edoardo, Pérez-González, Pablo, van der Werf, Paul, Greve, Thomas R., Wright, Gillian, Alonso-Herrero, Almudena, Álvarez-Márquez, Javier, Annunziatella, Marianna, Bik, Arjan, Bosman, Sarah, Costantin, Luca, Crespo Gómez, Alejandro, Dicken, Dan, Eckart, Andreas, Hjorth, Jens, Jermann, Iris, Labiano, Alvaro, Langeroodi, Danial, Meyer, Romain A., Moutard, Thibaud, Peißker, Florian, Pye, John P., Rinaldi, Pierluigi, Tikkanen, Tuomo V., Topinka, Martin, Henning, Thomas
• Format: Journal Article
• Language: English
• Published: Philadelphia The American Astronomical Society 01-07-2024; IOP Publishing
• Subjects: Active galactic nuclei; Astronomical models; Flux density; Galactic evolution; Galaxies; Galaxy evolution; Galaxy structure; High-redshift galaxies; Hubble deep field; Hubble Space Telescope; Infrared instruments; Infrared telescopes; Interstellar matter; Interstellar medium; James Webb Space Telescope; Millimeter astronomy; Point spread functions; Radio telescopes; Space telescopes; Star & galaxy formation; Star formation; Stars & galaxies; Stellar mass; Stellar structure; Wavelengths
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/1538-4357/ad43e5

Abstract We present deep James Webb Space Telescope (JWST)/Mid-Infrared Instrument (MIRI) F560W observations of a flux-limited, Atacama Large Millimeter/submillimeter Array (ALMA)-selected sample of 28 galaxies at z = 0.5–3.7 in the Hubble Ultra Deep Field (HUDF). The data from the MIRI Deep Imaging Survey (MIDIS) reveal the stellar structure of the HUDF galaxies at rest-frame wavelengths of λ > 1 μ m for the first time. We revise the stellar mass estimates using new JWST photometry and find good agreement with pre-JWST analyses; the few discrepancies can be explained by blending issues in the earlier lower-resolution Spitzer data. At z ∼ 2.5, the resolved rest-frame near-infrared (1.6 μ m) structure of the galaxies is significantly more smooth and centrally concentrated than seen by the Hubble Space Telescope at rest-frame 450 nm (F160W), with effective radii of R e (F560W) = 1–5 kpc and Sérsic indices mostly close to an exponential (disk-like) profile ( n ≈ 1), up to n ≈ 5 (excluding active galactic nuclei). We find an average size ratio of R e (F560W)/ R e (F160W) ≈ 0.7 that decreases with stellar mass. The stellar structure of the ALMA-selected galaxies is indistinguishable from a HUDF reference sample of all galaxies with a MIRI flux density greater than 1 μ Jy. We supplement our analysis with custom-made, position-dependent, empirical point-spread function models for the F560W observations. The results imply that a smoother stellar structure is in place in massive gas-rich, star-forming galaxies at “Cosmic Noon,” despite a more clumpy rest-frame optical appearance, placing additional constraints on galaxy formation simulations. As a next step, matched-resolution, resolved ALMA observations will be crucial to further link the mass- and light-weighted galaxy structures to the dusty interstellar medium.