Metal-polluted Population III Galaxies and How to Find Them
Observing Population III (hereafter PopIII) galaxies, the hosts of first-generation stars, remains challenging even with the JWST. The current few candidates have been identified through the combination of a prominent He II emission and the absence of metal lines, a well-known but extremely brief si...
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IOP Publishing
2025-01-01
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| Series: | The Astrophysical Journal Letters |
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| Online Access: | https://doi.org/10.3847/2041-8213/adf4e3 |
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| author | Elka Rusta Stefania Salvadori Viola Gelli Daniel Schaerer Alessandro Marconi Ioanna Koutsouridou Stefano Carniani |
| author_facet | Elka Rusta Stefania Salvadori Viola Gelli Daniel Schaerer Alessandro Marconi Ioanna Koutsouridou Stefano Carniani |
| author_sort | Elka Rusta |
| collection | DOAJ |
| description | Observing Population III (hereafter PopIII) galaxies, the hosts of first-generation stars, remains challenging even with the JWST. The current few candidates have been identified through the combination of a prominent He II emission and the absence of metal lines, a well-known but extremely brief signature of metal-free systems. Here, we accurately model the evolution of the emission from PopIII galaxies to increase the number of candidates in JWST observations. To achieve this, we employ a locally calibrated galaxy-formation model that self-consistently follows the star formation and chemical evolution initiated by the first stars. We find that PopIII galaxies can emit metal lines in their “self-polluted” phase, while galaxies host only metal-free stars, but the gas has been chemically enriched by the first supernovae. In this phase, PopIII galaxies have [O III ]/H β ≈ 1, which opens the pool of candidates to more easily detectable sources. We predict that the high He II emission of PopIII galaxies can last up to ≈20 Myr and that it is partly maintained in the “hybrid” phase, when PopIII and Population II stars coexist in the host galaxy. We propose novel diagnostics involving ultraviolet metal lines to select PopIII candidates in high- z JWST surveys. In JADES, we identify nine candidate galaxies with >25% of their stellar mass in metal-free stars, showcasing the effectiveness of our method. Ultimately, the key to discovering PopIII galaxies could be to catch them during their first episodes of chemical enrichment. |
| format | Article |
| id | doaj-art-353b6403ff9b4ba6a2256dba959549a2 |
| institution | Kabale University |
| issn | 2041-8205 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | The Astrophysical Journal Letters |
| spelling | doaj-art-353b6403ff9b4ba6a2256dba959549a22025-08-20T03:36:41ZengIOP PublishingThe Astrophysical Journal Letters2041-82052025-01-019892L3210.3847/2041-8213/adf4e3Metal-polluted Population III Galaxies and How to Find ThemElka Rusta0https://orcid.org/0009-0006-4326-6097Stefania Salvadori1https://orcid.org/0000-0001-7298-2478Viola Gelli2https://orcid.org/0000-0001-5487-0392Daniel Schaerer3https://orcid.org/0000-0001-7144-7182Alessandro Marconi4https://orcid.org/0000-0002-9889-4238Ioanna Koutsouridou5https://orcid.org/0000-0002-3524-7172Stefano Carniani6https://orcid.org/0000-0002-6719-380XDipartimento di Fisica e Astronomia, Università degli Studi di Firenze , Largo E. Fermi 1, 50125 Firenze, Italy ; elka.rusta@unifi.it; INAF/Osservatorio Astrofisico di Arcetri , Largo E. Fermi 5, 50125 Firenze, ItalyDipartimento di Fisica e Astronomia, Università degli Studi di Firenze , Largo E. Fermi 1, 50125 Firenze, Italy ; elka.rusta@unifi.it; INAF/Osservatorio Astrofisico di Arcetri , Largo E. Fermi 5, 50125 Firenze, ItalyCosmic Dawn Center (DAWN) , Denmark; Niels Bohr Institute, University of Copenhagen , Jagtvej 128, 2200 Copenhagen N, DenmarkDepartment of Astronomy, University of Geneva , Chemin Pegasi 51, 1290 Versoix, SwitzerlandDipartimento di Fisica e Astronomia, Università degli Studi di Firenze , Largo E. Fermi 1, 50125 Firenze, Italy ; elka.rusta@unifi.it; INAF/Osservatorio Astrofisico di Arcetri , Largo E. Fermi 5, 50125 Firenze, ItalyDipartimento di Fisica e Astronomia, Università degli Studi di Firenze , Largo E. Fermi 1, 50125 Firenze, Italy ; elka.rusta@unifi.itScuola Normale Superiore , Piazza dei Cavalieri 7, 56126 Pisa, ItalyObserving Population III (hereafter PopIII) galaxies, the hosts of first-generation stars, remains challenging even with the JWST. The current few candidates have been identified through the combination of a prominent He II emission and the absence of metal lines, a well-known but extremely brief signature of metal-free systems. Here, we accurately model the evolution of the emission from PopIII galaxies to increase the number of candidates in JWST observations. To achieve this, we employ a locally calibrated galaxy-formation model that self-consistently follows the star formation and chemical evolution initiated by the first stars. We find that PopIII galaxies can emit metal lines in their “self-polluted” phase, while galaxies host only metal-free stars, but the gas has been chemically enriched by the first supernovae. In this phase, PopIII galaxies have [O III ]/H β ≈ 1, which opens the pool of candidates to more easily detectable sources. We predict that the high He II emission of PopIII galaxies can last up to ≈20 Myr and that it is partly maintained in the “hybrid” phase, when PopIII and Population II stars coexist in the host galaxy. We propose novel diagnostics involving ultraviolet metal lines to select PopIII candidates in high- z JWST surveys. In JADES, we identify nine candidate galaxies with >25% of their stellar mass in metal-free stars, showcasing the effectiveness of our method. Ultimately, the key to discovering PopIII galaxies could be to catch them during their first episodes of chemical enrichment.https://doi.org/10.3847/2041-8213/adf4e3Population III starsHigh-redshift galaxiesChemical enrichmentJames Webb Space Telescope |
| spellingShingle | Elka Rusta Stefania Salvadori Viola Gelli Daniel Schaerer Alessandro Marconi Ioanna Koutsouridou Stefano Carniani Metal-polluted Population III Galaxies and How to Find Them The Astrophysical Journal Letters Population III stars High-redshift galaxies Chemical enrichment James Webb Space Telescope |
| title | Metal-polluted Population III Galaxies and How to Find Them |
| title_full | Metal-polluted Population III Galaxies and How to Find Them |
| title_fullStr | Metal-polluted Population III Galaxies and How to Find Them |
| title_full_unstemmed | Metal-polluted Population III Galaxies and How to Find Them |
| title_short | Metal-polluted Population III Galaxies and How to Find Them |
| title_sort | metal polluted population iii galaxies and how to find them |
| topic | Population III stars High-redshift galaxies Chemical enrichment James Webb Space Telescope |
| url | https://doi.org/10.3847/2041-8213/adf4e3 |
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