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JADES: the emergence and evolution of Lyα emission and constraints on the intergalactic medium neutral fraction

Abstract:
The rest-frame UV recombination emission line Lyα can be powered by ionising photons from young massive stars in star-forming galaxies, but the fact that it can be resonantly scattered by neutral gas complicates its interpretation. For reionisation-era galaxies, a neutral intergalactic medium will scatter Lyα from the line of sight, making Lyα a useful probe of the neutral fraction evolution. Here, we explore Lyα in JWST/NIRSpec spectra from the ongoing JADES programme, which targets hundreds of galaxies in the well-studied GOODS-S and GOODS-N fields. These sources are UV-faint (−20.4 < MUV < −16.4) and thus represent a poorly explored class of galaxy. We fitted the low spectral resolution spectra (R ∼ 100) of a subset of 84 galaxies in GOODS-S with zspec > 5.6 (as derived with optical lines) with line and continuum models to search for significant line emission. Through exploration of the R100 data, we find evidence for Lyα in 17 sources. This sample allowed us to place observational constraints on the fraction of galaxies with Lyα emission in the redshift range 5.6 < z < 7.5, with a decrease from z = 6 to z = 7. We also find a positive correlation between the Lyα equivalent width and MUV, as seen in other samples. We used these results to estimate the neutral gas fraction at z ∼ 7, and our estimates are in agreement with previous results (XHI ∼ 0.5 − 0.9).
Publication status:
Published
Peer review status:
Peer reviewed

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Publisher copy:
10.1051/0004-6361/202347099

Authors


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Institution:
University of Oxford
Division:
MPLS
Department:
Physics
Sub department:
Astrophysics
Role:
Author
More by this author
Institution:
University of Oxford
Division:
MPLS
Department:
Physics
Sub department:
Astrophysics
Role:
Author
More by this author
Institution:
University of Oxford
Division:
MPLS
Department:
Physics
Sub department:
Astrophysics
Role:
Author
ORCID:
0000-0001-5333-9970


More from this funder
Funder identifier:
https://ror.org/00k4n6c32
Grant:
789056
More from this funder
Funder identifier:
https://ror.org/0472cxd90
Grant:
695671
More from this funder
Funder identifier:
https://ror.org/057g20z61


Publisher:
EDP Sciences
Journal:
Astronomy & Astrophysics More from this journal
Volume:
683
Article number:
A238
Publication date:
2024-03-24
Acceptance date:
2023-12-20
DOI:
EISSN:
1432-0746
ISSN:
0004-6361


Language:
English
Keywords:
Pubs id:
1602244
Local pid:
pubs:1602244
Deposit date:
2024-01-17

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