The ALMA-CRISTAL survey: Widespread dust-obscured star formation in typical star-forming galaxies at z = 4–6

• Published in: Astronomy and astrophysics (Berlin) 2024-10, Vol.690, p.A197
• Main Authors: Mitsuhashi, Ikki, Tadaki, Ken-ichi, Ikeda, Ryota, Herrera-Camus, Rodrigo, Aravena, Manuel, De Looze, Ilse, Förster Schreiber, Natascha M., González-López, Jorge, Spilker, Justin, Assef, Roberto J., Bouwens, Rychard, Barcos-Munoz, Loreto, Birkin, Jack, Bowler, Rebecca A. A., Rivera, Gabriela Calistro, Davies, Rebecca, Da Cunha, Elisabete, Díaz-Santos, Tanio, Ferrara, Andrea, Fisher, Deanne B., Lee, Lilian L., Li, Juno, Lutz, Dieter, Relaño, Monica, Naab, Thorsten, Palla, Marco, Posses, Ana, Solimano, Manuel, Tacconi, Linda, Übler, Hannah, van der Giessen, Stefan, Veilleux, Sylvain
• Format: Article
• Language: English
• ISSN: 0004-6361; 1432-0746
• DOI: 10.1051/0004-6361/202348782

We present the morphological parameters and global properties of dust-obscured star formation in typical star-forming galaxies at z = 4–6. Among 26 galaxies composed of 20 galaxies observed by the Cycle-8 ALMA Large Program, CRISTAL, and 6 galaxies from archival data, we individually detect rest-frame 158 μm dust continuum emission from 19 galaxies, 9 of which are reported for the first time. The derived far-infrared luminosities are in the range log 10 L IR [ L ⊙ ] = 10.9 − 12.4, an order of magnitude lower than previously detected massive dusty star-forming galaxies (DSFGs). We find the average relationship between the fraction of dust-obscured star formation ( f obs ) and the stellar mass to be consistent with previous results at z = 4–6 in a mass range of log 10 M * [ M ⊙ ]∼9.5 − 11.0 and to show potential evolution from z = 6 − 9. The individual f obs exhibits significant diversity, and we find a potential correlation with the spatial offset between the dust and UV continuum, suggesting that inhomogeneous dust reddening may cause the source-to-source scatter in f obs . The effective radii of the dust emission are on average ∼1.5 kpc and are about two times more extended than those seen in rest-frame UV. The infrared surface densities of these galaxies (Σ IR ∼ 2.0 × 10 10 L ⊙ kpc −2 ) are one order of magnitude lower than those of DSFGs that host compact central starbursts. On the basis of the comparable contribution of dust-obscured and dust-unobscured star formation along with their similar spatial extent, we suggest that typical star-forming galaxies at z = 4 − 6 form stars throughout the entirety of their disks.