Characterising Ly
Springer Link (Chiba Institute of Technology)
Abstract
One of the major conundrums in contemporary extragalactic astrophysics is the apparent overabundance of a remarkable population of UV-bright galaxies at redshifts z ≳ 9. We analysed galaxies spectroscopically observed by JWST/NIRSpec PRISM and confirmed to lie at z > 9, with a sufficient signal-to-noise to carefully model their rest-frame UV-to-optical continua and line emission. In particular, we modelled the damped Lyman-α (Lyα) absorption (DLA) features of each galaxy to place observational constraints on the gas assembly of neutral atomic hydrogen (H I) onto the galaxy halos at the onset of cosmic reionisation. Based on the derived H I column densities and star formation rate (SFR) surface densities, we show that all galaxies are highly efficient at forming stars on rapid ∼10 − 100 Myr depletion timescales, greatly in excess compared to the canonical local Universe Kennicutt-Schmidt (KS) relation and predictions from state-of-the-art galaxy formation simulations. The dense H I gas appears to also drive the offset from the fundamental-metallicity relation (FMR) of these galaxies though its dust-to-gas (DTG) ratio is seemingly consistent with values derived for local galaxies except for the lowest metallicity sight lines. Our results provide the first robust observational constraints on the impact of pristine H I gas on early galaxy assembly, and they imply that a combination of highly efficient star formation and low dust obscuration can likely explain the UV brightness of galaxies at cosmic dawn.
Authors 25
-
Affiliation as printed
Cosmic Dawn Center (DAWN) , Denmark
Niels Bohr Institute , University of Copenhagen , Jagtvej 128 , 2200 Copenhagen N , Denmark
-
Affiliation as printed
Cosmic Dawn Center (DAWN) , Denmark
Niels Bohr Institute , University of Copenhagen , Jagtvej 128 , 2200 Copenhagen N , Denmark
-
Affiliation as printed
Cosmic Dawn Center (DAWN) , Denmark
Niels Bohr Institute , University of Copenhagen , Jagtvej 128 , 2200 Copenhagen N , Denmark
-
Affiliation as printed
Cosmic Dawn Center (DAWN) , Denmark
Niels Bohr Institute , University of Copenhagen , Jagtvej 128 , 2200 Copenhagen N , Denmark
-
Affiliation as printed
Institute for Computational Cosmology , Department of Physics , Durham University , South Road , Durham DH1 3LE , UK
-
Affiliation as printed
Cosmic Dawn Center (DAWN) , Denmark
Niels Bohr Institute , University of Copenhagen , Jagtvej 128 , 2200 Copenhagen N , Denmark
-
Affiliation as printed
Department of Astronomy , Yale University , New Haven , CT 06511 , USA
-
Affiliation as printed
Cosmic Dawn Center (DAWN) , Denmark
Niels Bohr Institute , University of Copenhagen , Jagtvej 128 , 2200 Copenhagen N , Denmark
-
Affiliation as printed
Cosmic Dawn Center (DAWN) , Denmark
Niels Bohr Institute , University of Copenhagen , Jagtvej 128 , 2200 Copenhagen N , Denmark
-
Stockholm University · AlbaNova
Affiliation as printed
Stockholm University , Department of Astronomy and Oskar Klein Centre for Cosmoparticle Physics , AlbaNova University Centre , SE-10691 , Stockholm , Sweden
-
Affiliation as printed
Department of Physics , School of Advanced Science and Engineering , Faculty of Science and Engineering , Waseda University , 3-4-1 Okubo , Shinjuku , Tokyo 169-8555 , Japan
Waseda Research Institute for Science and Engineering , Faculty of Science and Engineering , Waseda University , 3-4-1 Okubo , Shinjuku , Tokyo 169-8555 , Japan
-
Affiliation as printed
Cosmic Dawn Center (DAWN) , Denmark
Niels Bohr Institute , University of Copenhagen , Jagtvej 128 , 2200 Copenhagen N , Denmark
-
Massachusetts Institute of Technology
Affiliation as printed
MIT Kavli Institute for Astrophysics and Space Research , 70 Vassar Street , Cambridge , MA 02139 , USA
-
Leiden University · Leiden Observatory
Affiliation as printed
Leiden Observatory , Leiden University , PO Box 9513 , NL-2300 RA Leiden , The Netherlands
-
Affiliation as printed
School of Physics and Astronomy , University of Leicester , University Rd , Leicester LE1 7RH , United Kingdom
-
Affiliation as printed
Cavendish Laboratory , University of Cambridge , 19 JJ Thomson Avenue , Cambridge CB3 0HE , UK
Kavli Institute for Cosmology , University of Cambridge , Madingley Road , Cambridge CB3 0HA , UK
-
Affiliation as printed
Cosmic Dawn Center (DAWN) , Denmark
Niels Bohr Institute , University of Copenhagen , Jagtvej 128 , 2200 Copenhagen N , Denmark
-
DTU Space · Technical University of Denmark
Affiliation as printed
Cosmic Dawn Center (DAWN) , Denmark
DTU Space , Technical University of Denmark , Elektrovej 327 , DK2800 Kgs. Lyngby , Denmark
-
Max Planck Institute for Astronomy
Affiliation as printed
Max-Planck-Institut für Astronomie , Königstuhl 17 , D-69117 Heidelberg , Germany
-
Massachusetts Institute of Technology
Affiliation as printed
MIT Kavli Institute for Astrophysics and Space Research , 70 Vassar Street , Cambridge , MA 02139 , USA
-
University of Geneva · University of Toronto
Affiliation as printed
Department of Astronomy , University of Geneva , Chemin Pegasi 51 , 1290 Versoix , Switzerland
University of Toronto , Toronto , ON M5S 3H8 , Canada
Cited by 0 stored of 0
No patents citing this paper on Lens.org (checked 2026-10-11).