---
DOAJ_listed: '1'
OA_place: publisher
OA_type: gold
PlanS_conform: '1'
_id: '22364'
abstract:
- lang: eng
text: Finding the first generation of (Population III or Pop III) stars is one of
the most ambitious and exciting challenges of astrophysics. JWST opened concrete
prospects for their detection during the Epoch of Reionization, where increasing
evidence suggests that residual Pop III formation may persist, even within pristine
pockets of high-mass halos, due to inhomogeneous enrichment. However, the identification
of Pop III stars within globally enriched environments will be challenging. We
investigate the detectability of a subdominant Pop III component in/around massive
(M⋆ ≳ 10^9 M⊙) galaxies at z ≈ 6.5–9 from the dustyGadget cosmological simulation
suite, and the confusion arising from second-generation (Pop II) stars in their
surroundings. We find that young (≲1 Myr), massive (MIII ∼ 6 × 10^5 M⊙) Pop III
clusters forming within these galaxy environments are responsible for strong HeII1640
line emission (LHeII1640 ≳ 10^41 erg ^s−1), which would be detectable with ≈10(50)
hr of medium-resolution observations with NIRSpec/IFU at z ≈ 6(10). These bright
luminosities cannot be produced by standard Pop II populations alone. On the other
hand, the dominant Pop II component within massive “hybrid” Pop III hosts powers
strong metal line emission (L[OIII]5007 ≳ 10^42 erg s^−1), indicating that the
detection of metal lines alone cannot exclude the presence of Pop IIIs in high-z
galaxy environments. We further discuss candidate selection strategies based on
Lyα, Hα, and Hβ emission, and how spatially resolved observations may enable the
detection of isolated, pristine pockets in the outskirts of massive halos.
acknowledgement: We thank Elka Rusta and Stefania Salvadori for providing predictions
of the He II line luminosities from the NEFERTITI model. A.V. acknowledges funding
from the Cosmic Frontier Center and the University of Texas at Austin’s College
of Natural Sciences. A.V., L.G., and R.S. acknowledge support from the PRIN 2022
MUR project 2022CB3PJ3—First Light And Galaxy aSsembly (FLAGS) funded by the European
Union—Next Generation EU. J.B.M. was supported by NSF Grants AST-2307354 and AST-2408637,
and by the NSF-Simons AI Institute for Cosmic Origins. This research was also supported
in part by grant NSF PHY-2309135 to the Kavli Institute for Theoretical Physics
(KITP). R.V. acknowledges support from PRIN MUR “2022935STW” funded by European
Union-Next Generation EU, Missione 4 Componente 2 CUP C53D23000950006 and from Bando
Ricerca Fondamentale INAF 2023, Theory Grant “Theoretical models for Black Holes
Archaeology." C.D.C. acknowledges support from the European Union (ERC, AGENTS,
101076224).
article_number: '226'
article_processing_charge: Yes
article_type: original
arxiv: 1
author:
- first_name: Alessandra
full_name: Venditti, Alessandra
last_name: Venditti
- first_name: Luca
full_name: Graziani, Luca
last_name: Graziani
- first_name: Raffaella
full_name: Schneider, Raffaella
last_name: Schneider
- first_name: Volker
full_name: Bromm, Volker
last_name: Bromm
- first_name: Julian B.
full_name: Muñoz, Julian B.
last_name: Muñoz
- first_name: Claudia
full_name: Di Cesare, Claudia
id: 2d002343-372f-11ef-98ec-a164d20427cb
last_name: Di Cesare
- first_name: Rosa
full_name: Valiante, Rosa
last_name: Valiante
- first_name: Antonello
full_name: Calabrò, Antonello
last_name: Calabrò
- first_name: Roberto
full_name: Maiolino, Roberto
last_name: Maiolino
- first_name: Steven L.
full_name: Finkelstein, Steven L.
last_name: Finkelstein
- first_name: Massimiliano
full_name: Parente, Massimiliano
last_name: Parente
- first_name: Matteo
full_name: Saggini, Matteo
last_name: Saggini
- first_name: John
full_name: Chisholm, John
last_name: Chisholm
citation:
ama: 'Venditti A, Graziani L, Schneider R, et al. Catching the nebular needle in
a polluted haystack: Line-emission signatures from population III-forming pockets
around massive galaxies at the end of reionization. The Astrophysical Journal.
2026;1005(2). doi:10.3847/1538-4357/ae7b2c'
apa: 'Venditti, A., Graziani, L., Schneider, R., Bromm, V., Muñoz, J. B., Di Cesare,
C., … Chisholm, J. (2026). Catching the nebular needle in a polluted haystack:
Line-emission signatures from population III-forming pockets around massive galaxies
at the end of reionization. The Astrophysical Journal. IOP Publishing.
https://doi.org/10.3847/1538-4357/ae7b2c'
chicago: 'Venditti, Alessandra, Luca Graziani, Raffaella Schneider, Volker Bromm,
Julian B. Muñoz, Claudia Di Cesare, Rosa Valiante, et al. “Catching the Nebular
Needle in a Polluted Haystack: Line-Emission Signatures from Population III-Forming
Pockets around Massive Galaxies at the End of Reionization.” The Astrophysical
Journal. IOP Publishing, 2026. https://doi.org/10.3847/1538-4357/ae7b2c.'
ieee: 'A. Venditti et al., “Catching the nebular needle in a polluted haystack:
Line-emission signatures from population III-forming pockets around massive galaxies
at the end of reionization,” The Astrophysical Journal, vol. 1005, no.
2. IOP Publishing, 2026.'
ista: 'Venditti A, Graziani L, Schneider R, Bromm V, Muñoz JB, Di Cesare C, Valiante
R, Calabrò A, Maiolino R, Finkelstein SL, Parente M, Saggini M, Chisholm J. 2026.
Catching the nebular needle in a polluted haystack: Line-emission signatures from
population III-forming pockets around massive galaxies at the end of reionization.
The Astrophysical Journal. 1005(2), 226.'
mla: 'Venditti, Alessandra, et al. “Catching the Nebular Needle in a Polluted Haystack:
Line-Emission Signatures from Population III-Forming Pockets around Massive Galaxies
at the End of Reionization.” The Astrophysical Journal, vol. 1005, no.
2, 226, IOP Publishing, 2026, doi:10.3847/1538-4357/ae7b2c.'
short: A. Venditti, L. Graziani, R. Schneider, V. Bromm, J.B. Muñoz, C. Di Cesare,
R. Valiante, A. Calabrò, R. Maiolino, S.L. Finkelstein, M. Parente, M. Saggini,
J. Chisholm, The Astrophysical Journal 1005 (2026).
das_tickbox: '1'
dataavailabilitystatement: 'Software: dustyGadget (L. Graziani et al. 2020), BPASSv2.2.134
(J. J. Eldridge et al. 2017; E. R. Stanway & J. J. Eldridge 2018), Yggdrasil35 (E.
Zackrisson et al. 2011), Cloudy22.0136 (G. J. Ferland et al. 2017), NumPy37 (S.
van der Walt et al. 2011; C. R. Harris et al. 2020), matplotlib38 (J. D. Hunter
2007), SciPy39 (Jones et al. 2001; P. Virtanen et al. 2020).'
date_created: 2026-07-19T22:01:46Z
date_published: 2026-07-10T00:00:00Z
date_updated: 2026-07-20T13:07:08Z
day: '10'
ddc:
- '520'
department:
- _id: JoMa
doi: 10.3847/1538-4357/ae7b2c
external_id:
arxiv:
- '2603.27582'
file:
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has_accepted_license: '1'
intvolume: ' 1005'
issue: '2'
language:
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license: https://creativecommons.org/licenses/by/4.0/
month: '07'
oa: 1
oa_version: Published Version
project:
- _id: bd9b2118-d553-11ed-ba76-db24564edfea
grant_number: '101076224'
name: Young galaxies as tracers and agents of cosmic reionization
publication: The Astrophysical Journal
publication_identifier:
eissn:
- 1538-4357
issn:
- 0004-637X
publication_status: published
publisher: IOP Publishing
quality_controlled: '1'
researchdata_availability: no
scopus_import: '1'
status: public
supplementarymaterial: yes
title: 'Catching the nebular needle in a polluted haystack: Line-emission signatures
from population III-forming pockets around massive galaxies at the end of reionization'
tmp:
image: /images/cc_by.png
legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode
name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)
short: CC BY (4.0)
type: journal_article
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
volume: 1005
year: '2026'
...