How much gas and dust is in the z = 5.7 Lyman-break galaxy HZ10?
Year: 2026
Type: article
Abstract: Context. A complete overview of the stellar, gas and dust contents of galaxies is key to understanding their assembly at early times. However, an estimation of molecular and atomic gas reservoirs at high redshift relies on various indirect tracers, while robust dust mass measurements require multiband far-infrared continuum observations. Aims. We present a census of the full baryonic content of the main sequence star-forming galaxy HZ10 at z = 5.65, a unique case study where all the necessary tracers are available. Methods. We used new ALMA Band 10 ( λ rest ≈ 50 μm) and Band 4 (≈300 μm) observations toward HZ10, combined with data previously taken in ALMA Bands 6 through 9 (≈70 − 200 μm) to constrain its dust properties. We complete the baryonic picture using archival high-resolution [C II ] observations that provide both a dynamical mass and molecular and atomic gas mass estimates, a JVLA CO(2-1)-based molecular gas mass, and JWST metallicity and stellar mass measurements. Results. We detected continuum emission from HZ10 in Bands 10 and 4 at the 3.4 − 4.0 σ level. We measured a dust temperature of T dust = 37 +6 −5 K and dust mass of log( M dust / M ⊙ ) = 8.0 ± 0.1. By leveraging the dynamical constraints, we were able to infer its total gas budget. We find that commonly used [C II ]-to-H 2 and [C II ]-to-HI conversions might overpredict the gas mass relative to the dynamical mass. For this reason, we derived a [C II ]-to-total-ISM mass (atomic + molecular) conversion factor. For HZ10, this corresponds to α [CII] ISM = 38 +28 −26 M ⊙ L ⊙ −1 . We also found that HZ10 falls below the local scaling relation between the dust-to-gas ratio and metallicity, suggesting inefficient ISM dust growth. Conclusions. These results demonstrate a powerful synergy between ALMA and JWST in disentangling the baryonic components of early galaxies, paving the way for future studies of larger samples to dynamically calibrate [C II ]-to-gas mass conversion factors and further unravel the pathways of early dust buildup.
Source: Astronomy and Astrophysics
Authors: H. S. B. Algera, R. Herrera-Camus, M. Aravena, R. J. Assef, T. J. L. C. Bakx, A. Bolatto, K. Cescon, C.-C. Chen, E. da Cunha, P. Dayal, I. De Looze, T. Diaz-Santos, A. Faisst, A. Ferrara, N. Förster Schreiber, N. Hathi, R. Ikeda, H. Inami, G. C. Jones, A. Koekemoer, D. Lutz, M. Relaño, M. Romano, L. Rowland, L. Sommovigo, L. Vallini, A. Vijayan, V. Villanueva, P. van der Werf
Institutions: Institute of Astronomy and Astrophysics, Academia Sinica, Academia Sinica, University of Concepción, Universidad Diego Portales, Chalmers University of Technology, Joint Space Science Institute, Leiden University, Leiden Observatory, The University of Western Australia, International Centre for Radio Astronomy Research, University of Toronto, Canadian Institute for Theoretical Astrophysics, Ghent University, European University Cyprus, Foundation for Research and Technology Hellas, California Institute of Technology, Infrared Processing and Analysis Center, Scuola Normale Superiore, Max Planck Institute for Extraterrestrial Physics, Space Telescope Science Institute, The Graduate University for Advanced Studies, SOKENDAI, Tohoku University, National Astronomical Observatory of Japan, Hiroshima University, Hiroshima Astrophysical Science Center, University of Cambridge, National Radio Astronomy Observatory, Universidad de Granada, Max Planck Institute for Radio Astronomy, Osservatorio Astronomico di Padova, National Institute for Astrophysics, Flatiron Institute, Osservatorio di Astrofisica e Scienza dello Spazio, University of Sussex
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $1,865
OpenAlex ID: W7221032683