The ALMA-CRISTAL survey
Ikki Mitsuhashi, Ken-ichi Tadaki, Ryota Ikeda, Rodrigo Herrera-Camus, Manuel Aravena, Ilse De Looze, N. M. Förster Schreiber, Jorge González-López, Justin Spilker, Roberto J. Assef, Rychard Bouwens, Loreto Barcos-Muñoz, Jack E. Birkin, R. A. A. Bowler, G. Calistro Rivera, R. L. Davies, Elisabete da Cunha, T. Díaz-Santos, Andrea Ferrara, David B. Fisher, Lilian L. Lee, Juno Li, D. Lutz, M. Relaño, Thorsten Naab, Marco Palla, Ana Posses, Manuel Solimano, L. J. Tacconi, Hannah Übler, Stefan van der Giessen, Sylvain Veilleux
Abstract
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.