---
OA_place: publisher
OA_type: diamond
PlanS_conform: '1'
_id: '21045'
abstract:
- lang: eng
  text: 'The abundant population of little red dots (LRDs), compact objects with red
    UV to optical colors and broad Balmer lines at high redshift, is revealing new
    insights into the properties of early active galactic nuclei (AGN). Perhaps the
    most surprising features of this population are the presence of Balmer absorption
    and ubiquitous strong Balmer breaks. Recent models link these features to an active
    supermassive black hole (SMBH) cocooned in very dense gas (NH ∼ 1024 cm−2). We
    present a stringent test of such models using VLT/MUSE observations of A2744-45924,
    the most luminous LRD known to date (LHα ≈ 1044 erg s−1), located behind the Abell-2744
    lensing cluster at z = 4.464 (μ = 1.8). We detect a moderately extended Lyα nebula
    (h ≈ 5.7 pkpc), spatially offset from the point-like Hα seen by JWST by ≈1.6 pkpc.
    The Lyα emission is narrow (FWHM = 270 ± 15 km s−1), and faint (Lyα = 0.07Hα)
    compared to Lyα nebulae typically observed around quasars of similar luminosity.
    We detect compact N IV]λ1486 emission, spatially aligned with Hα, and a spatial
    shift in the far-UV continuum matching the Lyα offset. We discuss that Hα and
    Lyα have distinct physical origins: Hα originates from the AGN, while Lyα is powered
    by star formation. In the environment of A2744-45924, we identified four extended
    Lyα halos (Δz < 0.02, Δr < 100 pkpc). Their Lyα luminosities match the expectations
    based on Hα emission, and show no evidence for radiation from A2744-45924 affecting
    its surroundings. The lack of strong, compact, and broad Lyα and the absence of
    a luminous extended halo, suggest that the UV AGN light is obscured by dense gas
    cloaking the SMBH with a covering factor close to unity.'
acknowledgement: 'We thank the anonymous referee for constructive and useful comments.
  We thank Sebastiano Cantalupo for comments on the draft. Based on observations collected
  at the European Organisation for Astronomical Research in the Southern Hemisphere
  under ESO programme 114.27M6.001. 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. We acknowledge funding from JWST program GO-3516. This work is based in part
  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 #3516. MG thanks the Max Planck Society for support
  through the MPRG. FDE acknowledges support by the Science and Technology Facilities
  Council (STFC), by the ERC through Advanced Grant 695671 “QUENCH”, and by the UKRI
  Frontier Research grant RISEandFALL. TU acknowledges funding from the ERC-AdG grant
  SPECMAP-CGM, GA 101020943. GK acknowledges support from the MERAC foundation.'
article_number: A147
article_processing_charge: No
article_type: original
arxiv: 1
author:
- first_name: Alberto
  full_name: Torralba Torregrosa, Alberto
  id: 018f0249-0e87-11f0-b167-cbce08fbd541
  last_name: Torralba Torregrosa
  orcid: 0000-0001-5586-6950
- 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: Gabriele
  full_name: Pezzulli, Gabriele
  last_name: Pezzulli
- first_name: Tanya
  full_name: Urrutia, Tanya
  last_name: Urrutia
- first_name: Max
  full_name: Gronke, Max
  last_name: Gronke
- first_name: Sara
  full_name: Mascia, Sara
  id: edaf889c-c7cd-11ef-ab1b-bb28c431bd29
  last_name: Mascia
- first_name: Francesco
  full_name: D’Eugenio, Francesco
  last_name: D’Eugenio
- first_name: Claudia
  full_name: Di Cesare, Claudia
  id: 2d002343-372f-11ef-98ec-a164d20427cb
  last_name: Di Cesare
- first_name: Anna Christina
  full_name: Eilers, Anna Christina
  last_name: Eilers
- first_name: Jenny E.
  full_name: Greene, Jenny E.
  last_name: Greene
- first_name: Edoardo
  full_name: Iani, Edoardo
  id: 4053390a-6b68-11ef-9828-a3b8adef8d0a
  last_name: Iani
  orcid: 0000-0001-8386-3546
- first_name: Yuzo
  full_name: Ishikawa, Yuzo
  last_name: Ishikawa
- first_name: Ruari
  full_name: Mackenzie, Ruari
  last_name: Mackenzie
- first_name: Rohan P.
  full_name: Naidu, Rohan P.
  last_name: Naidu
- first_name: Benjamín
  full_name: Navarrete, Benjamín
  id: aa14a535-50c9-11ef-b52e-e0c373d10148
  last_name: Navarrete
- first_name: Gauri
  full_name: Kotiwale, Gauri
  id: 1438afc8-1ff6-11ee-9fa6-cd4a75d66875
  last_name: Kotiwale
citation:
  ama: Torralba Torregrosa A, Matthee JJ, Pezzulli G, et al. A weak Ly α halo for
    an extremely bright little red dot. Indications of enshrouded supermassive black
    hole growth. <i>Astronomy and Astrophysics</i>. 2026;705. doi:<a href="https://doi.org/10.1051/0004-6361/202555596">10.1051/0004-6361/202555596</a>
  apa: Torralba Torregrosa, A., Matthee, J. J., Pezzulli, G., Urrutia, T., Gronke,
    M., Mascia, S., … Kotiwale, G. (2026). A weak Ly α halo for an extremely bright
    little red dot. Indications of enshrouded supermassive black hole growth. <i>Astronomy
    and Astrophysics</i>. EDP Sciences. <a href="https://doi.org/10.1051/0004-6361/202555596">https://doi.org/10.1051/0004-6361/202555596</a>
  chicago: Torralba Torregrosa, Alberto, Jorryt J Matthee, Gabriele Pezzulli, Tanya
    Urrutia, Max Gronke, Sara Mascia, Francesco D’Eugenio, et al. “A Weak Ly α Halo
    for an Extremely Bright Little Red Dot. Indications of Enshrouded Supermassive
    Black Hole Growth.” <i>Astronomy and Astrophysics</i>. EDP Sciences, 2026. <a
    href="https://doi.org/10.1051/0004-6361/202555596">https://doi.org/10.1051/0004-6361/202555596</a>.
  ieee: A. Torralba Torregrosa <i>et al.</i>, “A weak Ly α halo for an extremely bright
    little red dot. Indications of enshrouded supermassive black hole growth,” <i>Astronomy
    and Astrophysics</i>, vol. 705. EDP Sciences, 2026.
  ista: Torralba Torregrosa A, Matthee JJ, Pezzulli G, Urrutia T, Gronke M, Mascia
    S, D’Eugenio F, Di Cesare C, Eilers AC, Greene JE, Iani E, Ishikawa Y, Mackenzie
    R, Naidu RP, Navarrete B, Kotiwale G. 2026. A weak Ly α halo for an extremely
    bright little red dot. Indications of enshrouded supermassive black hole growth.
    Astronomy and Astrophysics. 705, A147.
  mla: Torralba Torregrosa, Alberto, et al. “A Weak Ly α Halo for an Extremely Bright
    Little Red Dot. Indications of Enshrouded Supermassive Black Hole Growth.” <i>Astronomy
    and Astrophysics</i>, vol. 705, A147, EDP Sciences, 2026, doi:<a href="https://doi.org/10.1051/0004-6361/202555596">10.1051/0004-6361/202555596</a>.
  short: A. Torralba Torregrosa, J.J. Matthee, G. Pezzulli, T. Urrutia, M. Gronke,
    S. Mascia, F. D’Eugenio, C. Di Cesare, A.C. Eilers, J.E. Greene, E. Iani, Y. Ishikawa,
    R. Mackenzie, R.P. Naidu, B. Navarrete, G. Kotiwale, Astronomy and Astrophysics
    705 (2026).
corr_author: '1'
date_created: 2026-01-25T23:01:41Z
date_published: 2026-01-14T00:00:00Z
date_updated: 2026-02-16T07:46:53Z
day: '14'
ddc:
- '520'
department:
- _id: JoMa
- _id: GradSch
doi: 10.1051/0004-6361/202555596
external_id:
  arxiv:
  - '2505.09542'
file:
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  creator: dernst
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file_date_updated: 2026-02-16T07:35:03Z
has_accepted_license: '1'
intvolume: '       705'
language:
- iso: eng
license: https://creativecommons.org/licenses/by/4.0/
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: Astronomy and Astrophysics
publication_identifier:
  eissn:
  - 1432-0746
  issn:
  - 0004-6361
publication_status: published
publisher: EDP Sciences
quality_controlled: '1'
scopus_import: '1'
status: public
title: A weak Ly α halo for an extremely bright little red dot. Indications of enshrouded
  supermassive black hole growth
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: 705
year: '2026'
...