The JWST-PRIMAL archival survey

Context. One of the surprising early findings with JWST has been the discovery of a strong “roll-over” or a softening of the absorption edge of Ly α in a large number of galaxies at z ≳ 6, in addition to systematic offsets from photometric redshift estimates and fundamental galaxy scaling relations. This has been interpreted as strong cumulative damped Ly α absorption (DLA) wings from high column densities of neutral atomic hydrogen (H I ), signifying major gas accretion events in the formation of these galaxies. Aims. To explore this new phenomenon systematically, we assembled the JWST/NIRSpec PRImordial gas Mass AssembLy (PRIMAL) legacy survey of 584 galaxies at z = 5.0 − 13.4, designed to study the physical properties and gas in and around galaxies during the reionization epoch. Methods. We characterized this benchmark sample in full and spectroscopically derived the galaxy redshifts, metallicities, star formation rates, and ultraviolet (UV) slopes. We defined a new diagnostic, the Ly α damping parameter D Lyα , to measure and quantify the net effect of Ly α emission strength, the H I fraction in the intergalactic medium, or the local H I column density for each source. The JWST-PRIMAL survey is based on the spectroscopic DAWN JWST Archive (DJA-Spec). We describe DJA-Spec in this paper, detailing the reduction methods, the post-processing steps, and basic analysis tools. All the software, reduced spectra, and spectroscopically derived quantities and catalogs are made publicly available in dedicated repositories. Results. We find that the fraction of galaxies showing strong integrated DLAs with N HI > 10 21 cm −2 only increases slightly from ≈60% at z ≈ 6 up to ≈65 − 90% at z > 8. Similarly, the prevalence and prominence of Ly α emission is found to increase with decreasing redshift, in qualitative agreement with previous observational results. Strong Ly α emitters (LAEs) are predominantly found to be associated with low-metallicity and UV faint galaxies. By contrast, strong DLAs are observed in galaxies with a variety of intrinsic physical properties, but predominantly at high redshifts and low metallicities. Conclusions. Our results indicate that strong DLAs likely reflect a particular early assembly phase of reionization-era galaxies, at which point they are largely dominated by pristine H I gas accretion. At z = 8 − 10, this gas gradually cools and forms into stars that ionize their local surroundings, forming large ionized bubbles and producing strong observed Ly α emission at z < 8.

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Publication Details

Journal
Astronomy and Astrophysics
Published
2024-10-08
DOI
https://doi.org/10.1051/0004-6361/202450243
Citations
77
Primary Topic
Galaxies: Formation, Evolution, Phenomena
Type
article
Field-Weighted Citation Impact
25.53

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article

The JWST-PRIMAL archival survey

Matthew Hayes, Pratika Dayal, Francesco Valentino, Joris Witstok et al.
77 citations
Astronomy and Astrophysics
Galaxies: Formation, Evolution, Phenomena
25.53
article

The JWST-PRIMAL archival survey

Matthew Hayes, Pratika Dayal, Francesco Valentino, Joris Witstok, T. R. Greve, P. Jakobsson, Vadim Rusakov, Romeel Davé, F. Cullen, Marko Shuntov, Jorryt Matthee, Sophia R. Flury, Albert Sneppen, Karla Z. Arellano-Córdova, D. Watson, Abdurrouf, J. P. U. Fynbo, Rohan P. Naidu, A. P. Vijayan, K. E. Heintz, Kristian Finlator, John R. Weaver, N. R. Tanvir, Moire K. M. Prescott, John Wise, Andrea Ferrara, C. R. Christiansen, Desika Narayanan, G. Magdis, C. J. Pollock, A. C. Carnall, N. Khosravaninezhad, Peter Laursen, Meghana Killi, Viola Gelli, Pascal A. Oesch, Tiger Y. -Y Hsiao, Gabriel Brammer, Rashmi Gottumukkala, Anne Hutter, Steven Gillman, Renske Smit, Sune Toft, K. Lance Gould, S. E. Hardin, Chamilla Terp, Minju Lee, Laura C. Keating
article en
77 citations

Abstract

Context. One of the surprising early findings with JWST has been the discovery of a strong “roll-over” or a softening of the absorption edge of Ly α in a large number of galaxies at z ≳ 6, in addition to systematic offsets from photometric redshift estimates and fundamental galaxy scaling relations. This has been interpreted as strong cumulative damped Ly α absorption (DLA) wings from high column densities of neutral atomic hydrogen (H I ), signifying major gas accretion events in the formation of these galaxies. Aims. To explore this new phenomenon systematically, we assembled the JWST/NIRSpec PRImordial gas Mass AssembLy (PRIMAL) legacy survey of 584 galaxies at z = 5.0 − 13.4, designed to study the physical properties and gas in and around galaxies during the reionization epoch. Methods. We characterized this benchmark sample in full and spectroscopically derived the galaxy redshifts, metallicities, star formation rates, and ultraviolet (UV) slopes. We defined a new diagnostic, the Ly α damping parameter D Lyα , to measure and quantify the net effect of Ly α emission strength, the H I fraction in the intergalactic medium, or the local H I column density for each source. The JWST-PRIMAL survey is based on the spectroscopic DAWN JWST Archive (DJA-Spec). We describe DJA-Spec in this paper, detailing the reduction methods, the post-processing steps, and basic analysis tools. All the software, reduced spectra, and spectroscopically derived quantities and catalogs are made publicly available in dedicated repositories. Results. We find that the fraction of galaxies showing strong integrated DLAs with N HI > 10 21 cm −2 only increases slightly from ≈60% at z ≈ 6 up to ≈65 − 90% at z > 8. Similarly, the prevalence and prominence of Ly α emission is found to increase with decreasing redshift, in qualitative agreement with previous observational results. Strong Ly α emitters (LAEs) are predominantly found to be associated with low-metallicity and UV faint galaxies. By contrast, strong DLAs are observed in galaxies with a variety of intrinsic physical properties, but predominantly at high redshifts and low metallicities. Conclusions. Our results indicate that strong DLAs likely reflect a particular early assembly phase of reionization-era galaxies, at which point they are largely dominated by pristine H I gas accretion. At z = 8 − 10, this gas gradually cools and forms into stars that ionize their local surroundings, forming large ionized bubbles and producing strong observed Ly α emission at z < 8.

Astronomy and AstrophysicsVol. 693
New Mexico State University (US), University of California, Riverside (US), University of Geneva (CH), University of Copenhagen (DK), Space Telescope Science Institute (US), Georgia Institute of Technology (US), European Southern Observatory (DE), Johns Hopkins University (US), University of Leicester (GB), Scuola Normale Superiore (IT), Institute of Science and Technology Austria (AT), Stockholm University (SE), University of Iceland (IS), University of Groningen (NL), University of Cambridge (GB), University of Massachusetts Amherst (US), University of Florida (US), Kavli Institute for Particle Astrophysics and Cosmology (US), Royal Observatory (GB), AlbaNova (SE), University of Baltimore (US), Liverpool John Moores University (GB), Universidad Diego Portales (CL), Technical University of Denmark (DK), University of Edinburgh (GB)
National Science Foundation, National Aeronautics and Space Administration, Space Telescope Science Institute, UK Research and Innovation, European Commission, National Research Foundation, Rijksuniversiteit Groningen, Danmarks Grundforskningsfond, Nederlandse Organisatie voor Wetenschappelijk Onderzoek, Nuclear Safety and Security Commission, Vetenskapsrådet, Agencia Nacional de Investigación y Desarrollo, Horizon 2020 Framework Programme, Science and Technology Facilities Council, Staatssekretariat für Bildung, Forschung und Innovation
Openalex Percentile: Top 0%
Galaxies: Formation, Evolution, Phenomena
25.53
DOIOpen Access PDFOpenAlex
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