{
  "abstract": "The James Webb Space Telescope (JWST) is beginning to uncover a population of extremely metal-poor galaxies (EMPGs, $Z \\lt 1~{{\\ \\rm per\\ cent}}~\\mathrm{Z}_\\odot$) at redshift $z \\gt 3$, mostly through serendipitous Near Infrared Spectrograph (NIRSpec) discoveries and blind slitless spectroscopy. To accelerate our understanding of pristine star formation, we further develop a methodology to identify EMPG candidates from photometry, utilizing the extensive deep Near Infrared Camera (NIRCam) medium-band imaging from the JWST Advanced Deep Extragalactic Survey (JADES). Our EMPG candidates at $2.5 \\lt z \\lt 6.5$ exhibit strong photometric boosts by H$\\alpha$, yet correspondingly weak boosts by [O iii] + H$\\beta$, likely indicating extremely low metallicity to explain their lack of [O iii] emission. We further demand our EMPG candidates to have strong Balmer jumps, as revealed by medium-band imaging, to ensure that they are young starbursts, as opposed to broad-line active galactic nuclei/little red dots (AGN/LRDs), though contamination by dusty/dense-gas starbursts and highly obscured AGN remains a concern. Spectral Energy Distribution (SED)-fitting with near-pristine models (${\\sim }0.1$–$1~{{\\ \\rm per\\ cent}}~\\mathrm{Z}_\\odot$) indicates that our 14 EMPG candidates are low-mass (median $M_* \\approx 10^{6.7}~\\mathrm{M}_\\odot$), faint dwarf galaxies ($M_\\mathrm{UV} \\approx -16.9$), with high ionizing photon production efficiencies ($\\log \\, (\\xi _\\mathrm{ion, obs}/\\mathrm{(Hz\\ erg^{-1})}) \\approx 26.0$). Hence, these are plausible sites of near-pristine star formation, constituting ${\\sim }0.02$–0.4 per cent of $2.5 \\lt z \\lt 6.5$ galaxies at $-19 \\lt M_\\mathrm{UV} \\lt -16$. We discuss this extremely metal-poor extension to the mass–metallicity relation. We forecast that deep (${\\sim }28$ h) NIRCam slitless spectroscopy can identify bright EMPGs through strong H$\\beta$ but lack of [O iii] emission, or secure the redshifts of fainter systems through H$\\alpha$ detections. Highly multiplexed NIRSpec spectroscopy offers an alternate route to discovering the faintest pristine galaxies out to $z=10$, without requiring deep NIRCam medium-band and/or Mid-Infrared Instrument (MIRI) imaging to identify secure candidates.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2603.15761",
  "author_total": 30,
  "authors": [
    {
      "name": "James Trussler"
    },
    {
      "name": "Daniel Eisenstein"
    },
    {
      "name": "Andrew Bunker"
    },
    {
      "name": "Alex Cameron"
    },
    {
      "name": "Stefano Carniani"
    },
    {
      "name": "Stéphane Charlot"
    },
    {
      "name": "Jacopo Chevallard"
    },
    {
      "name": "Christopher Conselice"
    },
    {
      "name": "Mirko Curti"
    },
    {
      "name": "Emma Curtis-Lake"
    },
    {
      "name": "Francesco D’eugenio"
    },
    {
      "name": "Eiichi Egami"
    },
    {
      "name": "Kevin Hainline"
    },
    {
      "name": "Ryan Hausen"
    },
    {
      "name": "Jakob Helton"
    },
    {
      "name": "Tiger Yu-Yang Hsiao"
    },
    {
      "name": "Zhiyuan Ji"
    },
    {
      "name": "Benjamin Johnson"
    },
    {
      "name": "Tobias Looser"
    },
    {
      "name": "Roberto Maiolino"
    },
    {
      "name": "Dávid Puskás"
    },
    {
      "name": "Pierluigi Rinaldi"
    },
    {
      "name": "Brant Robertson"
    },
    {
      "name": "Fengwu Sun"
    },
    {
      "name": "Sandro Tacchella"
    },
    {
      "name": "Hannah Übler"
    },
    {
      "name": "Christina Williams"
    },
    {
      "name": "Christopher Willmer"
    },
    {
      "name": "Joris Witstok"
    },
    {
      "name": "Zihao Wu"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/21k8800yqcehj.bib",
  "cited_by": 1,
  "doi": "10.1093/mnras/stag1360",
  "fulltext_url": null,
  "id": "21k8800yqcehj",
  "issns": [
    "0035-8711",
    "1365-2966"
  ],
  "landing_url": "https://hal.science/hal-05760738v1",
  "language": "en",
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "hal",
      "0.phys"
    ],
    [
      "hal",
      "1.phys.astr"
    ],
    [
      "hal",
      "2.phys.astr.co"
    ],
    [
      "openalex",
      "3103|Galaxies: Formation, Evolution, Phenomena"
    ]
  ],
  "openalex": "W7169864250",
  "pdf_url": "https://hal.science/hal-05760738/document",
  "pmcid": null,
  "pmid": null,
  "published": "2026-08-25",
  "publisher": "Oxford University Press (OUP): Policy P - Oxford Open Option A",
  "ris": "https://research.draconitic.com/paper/21k8800yqcehj.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:17:50Z",
      "native_id": "hal-05760738",
      "source": "hal",
      "url": "https://hal.science/hal-05760738v1"
    }
  ],
  "subjects": [
    {
      "field": "astronomy",
      "origin": "hal:2.phys.astr.co",
      "subfield": "cosmology"
    },
    {
      "field": "physics",
      "origin": "hal:0.phys",
      "subfield": "general"
    }
  ],
  "title": "Out of oxygen: extremely metal-poor galaxy candidates identified at 2.5 < z < 6.5 with deep JADES medium-band imaging",
  "title_text": "Out of oxygen: extremely metal-poor galaxy candidates identified at 2.5 < z < 6.5 with deep JADES medium-band imaging",
  "type": "peer-reviewed",
  "updated_at": "2026-10-30T12:17:50Z",
  "url": "https://research.draconitic.com/paper/21k8800yqcehj",
  "venue": "Monthly Notices of the Royal Astronomical Society",
  "versions": []
}