---
DOAJ_listed: '1'
OA_place: publisher
OA_type: gold
PlanS_conform: '1'
_id: '23117'
abstract:
- lang: eng
  text: 'We present a comprehensive analysis of the relationship between galaxies
    and the intergalactic medium (IGM) during the late stages of cosmic reionization,
    based on the complete JWST EIGER dataset. Using deep NIRCam 3.5 μm slitless spectroscopy,
    we construct a sample of 948 [O iii]λ5008-emitting galaxies with −21.4 ≲ MUV ≲
    −17.2 spanning 5.33 < z < 6.97 along six quasar sight lines. We correlate these
    galaxies with Lyα and Lyβ transmission measured from high-resolution quasar spectra
    across multiple redshift intervals. We find clear redshift evolution in the correlation
    between galaxy density and transmission: it is suppressed in overdense regions
    at z < 5.50, while enhanced at 5.70 < z < 6.15. The intermediate range exhibits
    a transitional behavior. Cross-correlation measurements further reveal excess
    absorption within ∼8 cMpc of galaxies at low redshifts, and enhanced transmission
    at intermediate scales (∼5–20 cMpc) at z > 5.70. Statistical tests using mock
    catalogs with realistic galaxy clustering but no correlation with the transmission
    field confirm that the observed correlations are unlikely to arise by chance.
    The evolving signals can be explained by stronger absorption in overdense regions,
    combined with the competing influences of local radiation fields and the rising
    background radiation. While local radiation dominates ionization of the surrounding
    IGM at earlier times, the background becomes increasingly important, eventually
    surpassing the impact of nearby galaxies. These results support an inside-out
    progression of reionization, with ionized regions originating around clustered,
    star-forming galaxies and gradually extending into underdense regions.'
acknowledgement: "We thank Enrico Garaldi, Rahul Kannan, Aaron Smith, and the THESAN
  team for providing us with their simulation data, and Norbert Pirzkal for helpful
  advice on our NIRCam observing program.\r\n\r\nThis work is based on observations
  made with the NASA/ESA/CSA James Webb Space Telescope. The data were obtained from
  the Mikulski Archive for Space Telescopes at the Space Telescope Science Institute,
  which is operated by the Association of Universities for Research in Astronomy,
  Inc., under NASA contract NAS 5-03127 for JWST. These observations were taken under
  GTO program No. 1243. The specific observations analyzed can be accessed via doi:10.17909/6grb-j154.\r\n\r\nThe
  participation of S.J.L. as an Interdisciplinary Scientist in the JWST Flight Science
  Working Group 2002-2022 has been supported by the European Space Agency. His earlier
  involvement in the development of the JWST 1996–2001 was supported by the Canadian
  Space Agency.\r\n\r\nThis work is partially based on observations collected at the
  European Organisation for Astronomical Research in the Southern Hemisphere under
  ESO programmes 084.A-0360(A), 084.A-0390(A), 086.A-0162(A), 086.A-0574(A), 087.A-0607(A),
  089.A-0814(A), 093.A-0707(A), 098.B-0537(A), and 286.A-5025(A). Some of the data
  presented herein were obtained at Keck Observatory, which is a private 501(c)3 nonprofit
  organization operated as a scientific partnership among the California Institute
  of Technology, the University of California, and the National Aeronautics and Space
  Administration. The Observatory was made possible by the generous financial support
  of the W. M. Keck Foundation. This paper includes data gathered with the 6.5 m Magellan
  Telescopes located at Las Campanas Observatory, Chile.\r\n\r\nThis work has been
  supported by JSPS KAKENHI grant No. JP21K13956 (D.K.). J.M. is supported by the
  European Union (ERC, AGENTS, 101076224).\r\n\r\nFacilities: JWST - James Webb Space
  Telescope (NIRCam), VLT:Kueyen - Very Large Telescope (Kueyen) (X-Shooter), Magellan:Baade
  - Magellan I Walter Baade Telescope (FIRE), Keck:I - KECK I Telescope (MOSFIRE),
  Keck:II - KECK II Telescope (ESI).\r\n\r\nSoftware: Python, numpy (C. R. Harris
  et al. 2020), scipy (P. Virtanen et al. 2020), Astropy (Astropy Collaboration et
  al. 2013), Matplotlib (J. D. Hunter 2007), PypeIt (J. X. Prochaska et al. 2019)."
article_number: '280'
article_processing_charge: Yes
article_type: original
arxiv: 1
author:
- first_name: Daichi
  full_name: Kashino, Daichi
  last_name: Kashino
- first_name: Simon J.
  full_name: Lilly, Simon J.
  last_name: Lilly
- first_name: Jorryt J
  full_name: Matthee, Jorryt J
  id: 7439a258-f3c0-11ec-9501-9df22fe06720
  last_name: Matthee
  orcid: 0000-0003-2871-127X
- first_name: Ruari
  full_name: Mackenzie, Ruari
  last_name: Mackenzie
- first_name: Anna-Christina
  full_name: Eilers, Anna-Christina
  last_name: Eilers
- first_name: Rongmon
  full_name: Bordoloi, Rongmon
  last_name: Bordoloi
- first_name: Robert A.
  full_name: Simcoe, Robert A.
  last_name: Simcoe
- first_name: Rohan P.
  full_name: Naidu, Rohan P.
  last_name: Naidu
- first_name: Minghao
  full_name: Yue, Minghao
  last_name: Yue
- first_name: Bin
  full_name: Liu, Bin
  last_name: Liu
citation:
  ama: Kashino D, Lilly SJ, Matthee JJ, et al. EIGER. VII. The evolving relationship
    between galaxies and the intergalactic medium in the final stages of reionization.
    <i>The Astrophysical Journal</i>. 2026;997(2). doi:<a href="https://doi.org/10.3847/1538-4357/ae2799">10.3847/1538-4357/ae2799</a>
  apa: Kashino, D., Lilly, S. J., Matthee, J. J., Mackenzie, R., Eilers, A.-C., Bordoloi,
    R., … Liu, B. (2026). EIGER. VII. The evolving relationship between galaxies and
    the intergalactic medium in the final stages of reionization. <i>The Astrophysical
    Journal</i>. IOP Publishing. <a href="https://doi.org/10.3847/1538-4357/ae2799">https://doi.org/10.3847/1538-4357/ae2799</a>
  chicago: Kashino, Daichi, Simon J. Lilly, Jorryt J Matthee, Ruari Mackenzie, Anna-Christina
    Eilers, Rongmon Bordoloi, Robert A. Simcoe, Rohan P. Naidu, Minghao Yue, and Bin
    Liu. “EIGER. VII. The Evolving Relationship between Galaxies and the Intergalactic
    Medium in the Final Stages of Reionization.” <i>The Astrophysical Journal</i>.
    IOP Publishing, 2026. <a href="https://doi.org/10.3847/1538-4357/ae2799">https://doi.org/10.3847/1538-4357/ae2799</a>.
  ieee: D. Kashino <i>et al.</i>, “EIGER. VII. The evolving relationship between galaxies
    and the intergalactic medium in the final stages of reionization,” <i>The Astrophysical
    Journal</i>, vol. 997, no. 2. IOP Publishing, 2026.
  ista: Kashino D, Lilly SJ, Matthee JJ, Mackenzie R, Eilers A-C, Bordoloi R, Simcoe
    RA, Naidu RP, Yue M, Liu B. 2026. EIGER. VII. The evolving relationship between
    galaxies and the intergalactic medium in the final stages of reionization. The
    Astrophysical Journal. 997(2), 280.
  mla: Kashino, Daichi, et al. “EIGER. VII. The Evolving Relationship between Galaxies
    and the Intergalactic Medium in the Final Stages of Reionization.” <i>The Astrophysical
    Journal</i>, vol. 997, no. 2, 280, IOP Publishing, 2026, doi:<a href="https://doi.org/10.3847/1538-4357/ae2799">10.3847/1538-4357/ae2799</a>.
  short: D. Kashino, S.J. Lilly, J.J. Matthee, R. Mackenzie, A.-C. Eilers, R. Bordoloi,
    R.A. Simcoe, R.P. Naidu, M. Yue, B. Liu, The Astrophysical Journal 997 (2026).
das_tickbox: '0'
date_created: 2026-10-12T12:17:25Z
date_published: 2026-01-28T00:00:00Z
date_updated: 2026-10-14T08:12:05Z
day: '28'
ddc:
- '520'
department:
- _id: JoMa
doi: 10.3847/1538-4357/ae2799
external_id:
  arxiv:
  - '2506.03121'
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fulldoi: https://doi.org/10.3847/1538-4357/ae2799
has_accepted_license: '1'
intvolume: '       997'
issue: '2'
language:
- iso: eng
month: '01'
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: EIGER. VII. The evolving relationship between galaxies and the intergalactic
  medium in the final stages of reionization
tmp:
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  name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)
  short: CC BY (4.0)
type: journal_article
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volume: 997
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...