---
_id: '17889'
abstract:
- lang: eng
  text: The increasingly neutral intergalactic gas at z > 6 impacts the Lyman-α (Lyα)
    flux observed from galaxies. One luminous galaxy, COLA1, stands out because of
    its unique double-peaked Lyα line at z = 6.6, unseen in any simulation of reionization.
    Here, we present JWST/NIRCam wide-field slitless spectroscopy in a 21 arcmin2
    field centered on COLA1. We find 141 galaxies spectroscopically selected through
    the [O III] doublet at 5.35 < z < 6.95, with 40 of these sources showing Hβ. For
    COLA1, we additionally detect [O III]4363 as well as Hγ. We measure a systemic
    redshift of z = 6.5917 for COLA1, confirming the classical double-peak nature
    of the Lyα profile. This implies that it resides in a highly ionized bubble and
    that it is leaking ionizing photons with a high escape fraction of fesc(LyC) = 20–50%,
    making it a prime laboratory to study Lyman continuum escape in the Epoch of Reionization.
    COLA1 shows all the signs of a prolific ionizer with a Lyα escape fraction of
    81 ± 5%, Balmer decrement indicating no dust, a steep UV slope (βUV = −3.2 ± 0.4),
    and a star-formation surface density ≳10× that of typical galaxies at similar
    redshift. We detect five galaxies in COLA1’s close environment (Δz < 0.02). Exploiting
    the high spectroscopic completeness inherent to grism surveys, and using mock
    simulations that fully mimic the selection function, we show that the number of
    detected companions is very typical for a normal similarly UV-bright (MUV ∼ −21.3)
    galaxy – that is, the ionized bubble around COLA1 is unlikely to be due to an
    excessively large over-density. Instead, the measured ionizing properties suggest
    that COLA1 by itself might be powering the bubble required to explain its double-peaked
    Lyα profile (Rion ≈ 0.7 pMpc), with only minor contributions from detected neighbors
    (−19.5 ≲ MUV ≲ −17.5).
acknowledgement: 'The authors acknowledge the financial support from the MICIU with
  funding from the European Union NextGenerationEU and Generalitat Valenciana in the
  call Programa de Planes Complementarios de I+D+i (PRTR 2022) Project (VAL-JPAS),
  reference ASFAE/2022/025. This work has been funded by project PID2019-109592GBI00/AEI/10.13039/501100011033
  from the Spanish Ministerio de Ciencia e Innovación (MCIN)-Agencia Estatal de Investigación,
  by the Project of Excellence Prometeo/2020/085 from the Conselleria d’Innovació
  Universitats, Ciència i Societat Digital de la Generalitat Valenciana. It has also
  be funded by the Project of Excellence Prometeo/2020/085 from the Conselleria d’Educació,
  Universitats, i Ocupació de la Generalitat Valenciana. Funded by the European Union
  (ERC, AGENTS, 101076224). Views and opinions expressed are however those of the
  author(s) only and do not necessarily reflect those of the European Union or the
  European Research Council. Neither the European Union nor the granting authority
  can be held responsible for them. ST acknowledges support by the Royal Society Research
  Grant G125142. AH acknowledges support by the VILLUM FONDEN under grant 37459. The
  Cosmic Dawn Center (DAWN) is funded by the Danish National Research Foundation under
  grant DNRF140. We acknowledge funding from JWST program GO-1933. Support for this
  work was provided by NASA through the NASA Hubble Fellowship grant HST-HF2-51515.001-A
  awarded by the Space Telescope Science Institute, which is operated by the Association
  of Universities for Research in Astronomy, Incorporated, under NASA contract NAS5-26555.
  This work has received funding from the Swiss State Secretariat for Education, Research
  and Innovation (SERI) under contract number MB22.00072, as well as from the Swiss
  National Science Foundation (SNSF) through project grant 200020_207349. This 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 are associated with program # 1933. The specific observations analyzed
  can be accessed via https://doi.org/10.17909/s9ht-7n34.'
article_number: A44
article_processing_charge: Yes (in subscription journal)
article_type: original
arxiv: 1
author:
- first_name: Alberto
  full_name: Torralba-Torregrosa, Alberto
  last_name: Torralba-Torregrosa
- 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: Rohan P.
  full_name: Naidu, Rohan P.
  last_name: Naidu
- first_name: Ruari
  full_name: Mackenzie, Ruari
  last_name: Mackenzie
- first_name: Gabriele
  full_name: Pezzulli, Gabriele
  last_name: Pezzulli
- first_name: Anne
  full_name: Hutter, Anne
  last_name: Hutter
- first_name: Pablo
  full_name: Arnalte-Mur, Pablo
  last_name: Arnalte-Mur
- first_name: Siddhartha
  full_name: Gurung-López, Siddhartha
  last_name: Gurung-López
- first_name: Sandro
  full_name: Tacchella, Sandro
  last_name: Tacchella
- first_name: Pascal
  full_name: Oesch, Pascal
  last_name: Oesch
- first_name: Daichi
  full_name: Kashino, Daichi
  last_name: Kashino
- first_name: Charlie
  full_name: Conroy, Charlie
  last_name: Conroy
- first_name: David
  full_name: Sobral, David
  last_name: Sobral
citation:
  ama: 'Torralba-Torregrosa A, Matthee JJ, Naidu RP, et al. Anatomy of an ionized
    bubble: NIRCam grism spectroscopy of the z = 6.6 double-peaked Lyman- α emitter
    COLA1 and its environment. <i>Astronomy &#38; Astrophysics</i>. 2024;689. doi:<a
    href="https://doi.org/10.1051/0004-6361/202450318">10.1051/0004-6361/202450318</a>'
  apa: 'Torralba-Torregrosa, A., Matthee, J. J., Naidu, R. P., Mackenzie, R., Pezzulli,
    G., Hutter, A., … Sobral, D. (2024). Anatomy of an ionized bubble: NIRCam grism
    spectroscopy of the z = 6.6 double-peaked Lyman- α emitter COLA1 and its environment.
    <i>Astronomy &#38; Astrophysics</i>. EDP Sciences. <a href="https://doi.org/10.1051/0004-6361/202450318">https://doi.org/10.1051/0004-6361/202450318</a>'
  chicago: 'Torralba-Torregrosa, Alberto, Jorryt J Matthee, Rohan P. Naidu, Ruari
    Mackenzie, Gabriele Pezzulli, Anne Hutter, Pablo Arnalte-Mur, et al. “Anatomy
    of an Ionized Bubble: NIRCam Grism Spectroscopy of the z = 6.6 Double-Peaked Lyman-
    α Emitter COLA1 and Its Environment.” <i>Astronomy &#38; Astrophysics</i>. EDP
    Sciences, 2024. <a href="https://doi.org/10.1051/0004-6361/202450318">https://doi.org/10.1051/0004-6361/202450318</a>.'
  ieee: 'A. Torralba-Torregrosa <i>et al.</i>, “Anatomy of an ionized bubble: NIRCam
    grism spectroscopy of the z = 6.6 double-peaked Lyman- α emitter COLA1 and its
    environment,” <i>Astronomy &#38; Astrophysics</i>, vol. 689. EDP Sciences, 2024.'
  ista: 'Torralba-Torregrosa A, Matthee JJ, Naidu RP, Mackenzie R, Pezzulli G, Hutter
    A, Arnalte-Mur P, Gurung-López S, Tacchella S, Oesch P, Kashino D, Conroy C, Sobral
    D. 2024. Anatomy of an ionized bubble: NIRCam grism spectroscopy of the z = 6.6
    double-peaked Lyman- α emitter COLA1 and its environment. Astronomy &#38; Astrophysics.
    689, A44.'
  mla: 'Torralba-Torregrosa, Alberto, et al. “Anatomy of an Ionized Bubble: NIRCam
    Grism Spectroscopy of the z = 6.6 Double-Peaked Lyman- α Emitter COLA1 and Its
    Environment.” <i>Astronomy &#38; Astrophysics</i>, vol. 689, A44, EDP Sciences,
    2024, doi:<a href="https://doi.org/10.1051/0004-6361/202450318">10.1051/0004-6361/202450318</a>.'
  short: A. Torralba-Torregrosa, J.J. Matthee, R.P. Naidu, R. Mackenzie, G. Pezzulli,
    A. Hutter, P. Arnalte-Mur, S. Gurung-López, S. Tacchella, P. Oesch, D. Kashino,
    C. Conroy, D. Sobral, Astronomy &#38; Astrophysics 689 (2024).
das_tickbox: '1'
date_created: 2024-09-08T22:01:11Z
date_published: 2024-09-01T00:00:00Z
date_updated: 2026-07-08T06:45:34Z
day: '01'
ddc:
- '520'
department:
- _id: JoMa
doi: 10.1051/0004-6361/202450318
external_id:
  arxiv:
  - '2404.10040'
  isi:
  - '001303205700016'
file:
- access_level: open_access
  checksum: a6c0df287c75e8929db9f42badeac859
  content_type: application/pdf
  creator: dernst
  date_created: 2024-09-11T07:35:00Z
  date_updated: 2024-09-11T07:35:00Z
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  file_name: 2024_AstronomyAstrophysics_TorralbaTorregrosa.pdf
  file_size: 6225413
  relation: main_file
  success: 1
file_date_updated: 2024-09-11T07:35:00Z
has_accepted_license: '1'
intvolume: '       689'
isi: 1
language:
- iso: eng
month: '09'
oa: 1
oa_version: Published Version
publication: Astronomy & Astrophysics
publication_identifier:
  eissn:
  - 1432-0746
  issn:
  - 0004-6361
publication_status: published
publisher: EDP Sciences
quality_controlled: '1'
scopus_import: '1'
status: public
title: 'Anatomy of an ionized bubble: NIRCam grism spectroscopy of the z = 6.6 double-peaked
  Lyman- α emitter COLA1 and its environment'
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: 689
year: '2024'
...