Year: 2026
Type: article
Abstract: We study bulge formation in 16 massive dusty star-forming galaxies at z ∼ 2 by combining JWST MIRI F770W imaging, NIRCam imaging in eight bands, and Atacama Large Millimeter/submillimeter Array (ALMA) 870 μ m data. At the median redshift of z = 2.18, the F770W band probes the rest-frame 2.4 μ m light, close to the rest-frame K band, and traces the stellar mass distribution with much less dust attenuation than the NIRCam bands. The effective radii measured in F770W agree with those of the 870 μ m dust emission, with a median ratio of 0.95, and are typically 23% smaller than those in F444W. The rest-frame K -band imaging is, therefore, essential to measure the true extent of the stellar mass, which is as compact as the dusty star-forming regions. In stacks of the 16 galaxies at a matched resolution, the 870 μ m and F770W profiles agree closely out to 8 kpc, and a bulge plus disk decomposition of the F770W stack gives a bulge-to-total ratio of 0.50. Fitting the spectral energy distributions (SEDs) in radial bins with CIGALE, we find that the attenuation decreases from A V = 3.7 mag at the center to 1.9 mag at r ≳ 7 kpc, while the specific star formation rate profile is flat. In most of the galaxies, the bulge is already in place inside the dusty core. In two galaxies, by contrast, the 870 μ m emission is 3–6 times more compact than the F770W light, which suggests that they are still in the bulge-building compaction phase. Our sample may, thus, catch massive galaxies in several phases of bulge formation.
Source: The Astrophysical Journal
Author: Ken-ichi Tadaki
Institution: Hokkai Gakuen University
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $4,499
Funders: National Science Foundation, National Aeronautics and Space Administration, National Radio Astronomy Observatory, National Research Foundation, Danmarks Grundforskningsfond, Korea Astronomy and Space Science Institute, National Astronomical Observatory of Japan, National Science and Technology Council, Japan Society for the Promotion of Science, National Institutes of Natural Sciences
OpenAlex ID: W7221790367