Low Dust Mass and High Star Formation Efficiency at z > 12 from Deep ALMA Observations
Journal article, 2026
We investigate the dust mass buildup and star formation efficiency of two galaxies at z > 12—GHZ2 and GS-z14-0—by combining Atacama Large Millimeter/submillimeter Array and JWST observations with an analytical model that assumes dust at thermal equilibrium. We obtained 3σ constraints on the dust mass of log Mdust/M⊙ < 5.0 and <5.3, respectively. These constraints are in tension with a high dust condensation efficiency in stellar ejecta but are consistent with models with a short metal accretion timescale at z > 12. Given the young stellar ages of these galaxies (tage ∼ 10 Myr), dust grain growth via accretion may still be ineffective at this stage, though it likely works efficiently to produce significant dust in galaxies at z ∼ 7. The star formation efficiencies, defined as the star formation rate divided by the molecular gas mass, reach ∼10 Gyr−1 over a 10 Myr timescale, aligning with the expected redshift evolution of “starburst” galaxies with efficiencies that are ∼0.5-1 dex higher than those in main-sequence galaxies. This starburst phase seems to be common in UV-bright galaxies at z > 12 and is likely associated with the unique conditions of the early phases of galaxy formation, such as bursty star formation. Direct observations of molecular gas tracers like [C ii] will be crucial to further understanding the nature of bright galaxies at z > 12.
Author
Ikki Mitsuhashi
University of Colorado
Waseda University
National Astronomical Observatory of Japan
J. A. Zavala
National Astronomical Observatory of Japan
University of Massachusetts
Tom Bakx
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
Akio K. Inoue
Waseda University
M. Castellano
Osservatorio Astronomico di Roma
Antonello Calabrò
Osservatorio Astronomico di Roma
Caitlin M. Casey
University of Texas
M. Franco
University of Texas
B. Hatsukade
University of Tokyo
National Astronomical Observatory of Japan
The Graduate University for Advanced Studies (SOKENDAI)
N. Hathi
Space Telescope Science Institute (STScI)
Ryota Ikeda
National Astronomical Observatory of Japan
The Graduate University for Advanced Studies (SOKENDAI)
Anton M. Koekemoer
Space Telescope Science Institute (STScI)
Jeyhan S. Kartaltepe
Rochester Institute of Technology
Kirsten Knudsen
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
P. Santini
Osservatorio Astronomico di Roma
T. Saito
University of Shizuoka
Elena Terlevich
National Institute of Astrophysics, Optics and Electronics
University of Cambridge
National University of La Plata
Roberto Terlevich
National Institute of Astrophysics, Optics and Electronics
National University of La Plata
University of Cambridge
L. Y.Aaron Yung
Space Telescope Science Institute (STScI)
Astrophysical Journal
0004-637X (ISSN) 1538-4357 (eISSN)
Vol. 1000 2 159The Origin and Fate of Dust in Our Universe
Knut and Alice Wallenberg Foundation (KAW 2019.0443), 2020-06-01 -- 2023-05-31.
Knut and Alice Wallenberg Foundation (KAW 2020.0081), 2021-07-01 -- 2026-06-30.
Subject Categories (SSIF 2025)
Astronomy, Astrophysics, and Cosmology
DOI
10.3847/1538-4357/ae4511