Deciphering the nature of Virgil: An obscured active galactic nucleus lurking within an apparently normal Lyα emitter during cosmic reionization
Rinaldi P, Pérez-González PG, Rieke GH, Lyu J, D’Eugenio F, Wu Z, Carniani S, Looser TJ, Shivaei I, Boogaard LA, Diaz-Santos T, Colina L, Östlin G, Alberts S, Álvarez-Márquez J, Annuziatella M, Aravena M, Bhatawdekar R, Bunker AJ, Caputi KI, Charlot S, Crespo Gómez A, Curti M, Eckart A, Gillman S, Hainline K, Kumari N, Hjorth J, Iani E, Inami H, Ji Z, Johnson BD, Jones GC, Labiano Á, Maiolino R, Melinder J, Moutard T, Peissker F, Rieke M, Robertson B, Scholtz J, Tacchella S, Van Der Werf PP, Walter F, Williams CC, Willott C, Witstok J, Übler H, Zhu Y. 2025. Deciphering the nature of Virgil: An obscured active galactic nucleus lurking within an apparently normal Lyα emitter during cosmic reionization. The Astrophysical Journal. 994(1), 86.
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Author
Rinaldi, Pierluigi;
Pérez-González, Pablo G.;
Rieke, George H.;
Lyu, Jianwei;
D’Eugenio, Francesco;
Wu, Zihao;
Carniani, Stefano;
Looser, Tobias J.;
Shivaei, Irene;
Boogaard, Leindert A.;
Diaz-Santos, Tanio;
Colina, Luis
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All
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Abstract
We present a comprehensive analysis of the MIRI Extremely Red Object Virgil, a Lyα emitter at zspec = 6.6379 ± 0.0035 with the photometric properties of a Little Red Dot. Leveraging new JWST/MIRI imaging from the MIDIS and PAHSPECS programs, we confirm Virgil’s extraordinary nature among galaxies in JADES/GOODS-South, exhibiting a strikingly red NIRCam-to-MIRI color (F444W–F1500W = 2.84 ± 0.04 mag). Deep NIRSpec/PRISM spectroscopy from the OASIS program offers key insights into the host galaxy, revealing properties of an average star-forming galaxy during Cosmic Reionization, such as a subsolar metallicity, low-to-moderate dust content, and a relatively high ionization parameter and electron temperature. By estimating the star formation rate of Virgil from UV and Hα, we find evidence that the galaxy is either entering or fading out of a bursty episode. Although line-ratio diagnostics employed at high z would classify Virgil as an active galactic nucleus (AGN), this classification becomes ambiguous once redshift evolution is considered. Nonetheless, Virgil occupies the same parameter space as recently confirmed AGNs at similar redshifts. The new deep MIRI data at 15 μm reinforce the AGN nature of Virgil, as inferred from multiple spectral energy distribution (SED) fitting codes. Virgil’s rising infrared SED and UV excess resemble those of Dust-Obscured Galaxies (DOGs) studied with Spitzer at Cosmic Noon, particularly blue-excess HotDOGs. Our results highlight the need for a multiwavelength approach incorporating MIRI to uncover such extreme sources at z ≳ 6 and to shed light on the interplay between galaxy evolution and early black hole growth during Cosmic Reionization.
Publishing Year
Date Published
2025-11-20
Journal Title
The Astrophysical Journal
Publisher
IOP Publishing
Acknowledgement
The authors are deeply grateful to Antonello Calabrò for valuable insights on CLOUDY and pyCloudy, and for publicly sharing their SFG and AGN models, which were used as a reference to verify the consistency of our photoionization models. The authors also thank Adam Carnall for insightful input on bagpipes and for assistance with the implementation of the two-population model adopted in this work. Finally, they also thank Camilla Pacifici, Vasily Kokorev, and Cristian Vignali for their insightful discussions.
This work is based on observations made with the NASA/ESA/CSA JWST. The data were obtained from the Mikulski Archive for Space Telescopes (MAST) 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 JWST programs GTO #1180, GO #1210, GTO#1283, GO #1963, GO #1895, GO# 3215, and GO#6511.
The authors acknowledge the FRESCO, JEMS, and #3215 teams led by co-PIs P. Oesch, C. C. Williams, M. Maseda, D. Eisenstein, and R. Maiolino for developing their observing program with a zero-exclusive-access period. Processing for the JADES NIRCam data release was performed on the lux cluster at the University of California, Santa Cruz, funded by NSF MRI grant AST 1828315. Also based on observations made with the NASA/ESA Hubble Space Telescope obtained from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 526555. The data presented in this article were obtained from MAST at the Space Telescope Science Institute. The specific observations analyzed can be accessed via doi: 10.17909/1rq3-8048 P. Oesch & D. Magee (2023), C. Williams et al. (2023), G. Illingworth (2015), and M. Rieke et al. (2023).
A.J.B. acknowledges funding from the “FirstGalaxies” Advanced Grant from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grant agreement No. 789056).
P.G.P.-G. acknowledges support from grant PID2022-139567NB-I00 funded by the Spanish Ministerio de Ciencia e Innovación MCIN/AEI/10.13039/501100011033, FEDER, UE.
B.E.R. acknowledges support from the NIRCam Science Team contract to the University of Arizona, NAS5-02015, and JWST Program 3215.
S.T. acknowledges support by the Royal Society Research Grant G125142.
The research of C.C.W. is supported by NOIRLab, which is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the National Science Foundation.
J.W. gratefully acknowledges support from the Cosmic Dawn Center through the DAWN Fellowship. The Cosmic Dawn Center (DAWN) is funded by the Danish National Research Foundation under grant No. 140.
Y.Z., Z.J., and P.L. gratefully acknowledge the JWST/NIRCam contract to the University of Arizona NAS5-02015.
The work of G.H.R. and P.L. was also supported by grant 80NSSC18K0555, from the NASA Goddard Space Flight Center to the University of Arizona.
H.Ü. acknowledges funding by the European Union (ERC APEX, 101164796). Views and opinions expressed are however those of the authors only and do not necessarily reflect those of the European Union or the European Research Council Executive Agency. Neither the European Union nor the granting authority can be held responsible for them.
G.C.J. acknowledges support by the Science and Technology Facilities Council (STFC), ERC Advanced grant 695671 “QUENCH.”
A.C.G. acknowledges support by JWST contract B0215/JWST-GO-02926.
G.O. acknowledges support from the Swedish National Space Agency (SNSA).
H.I. acknowledges support from JSPS KAKENHI grant No. JP21H01129.
M.A. gratefully acknowledges support from ANID Basal Project FB210003 and ANID MILENIO NCN2024_112.
T.D.S. acknowledges the research project was supported by the Hellenic Foundation for Research and Innovation (HFRI) under the “2nd Call for HFRI Research Projects to Support Faculty Members and Researchers” (project No.: 03382).
R.M. 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. R.M. also acknowledges funding from a research professorship from the Royal Society.
I.S. acknowledges funding from the Atraccíon de Talento grant No. 2022-T1/TIC-20472 of the Comunidad de Madrid, Spain, and the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grant No. 101117541, DistantDust).
K.I.C. acknowledges funding from the Dutch Research Council (NWO) through the award of the Vici grant VI.C.212.036.
Facilities: HST - Hubble Space Telescope satellite, JWST. -
Software: Astropy (Astropy Collaboration et al. 2022), Bagpipes (A. C. Carnall et al. 2019), MSAEXP (G. Brammer 2023) NumPy (C. R. Harris et al. 2020), pandas (The pandas development team 2024) Photutils (L. Bradley et al. 2016), TOPCAT (M. Taylor 2022).
Volume
994
Issue
1
Article Number
86
ISSN
eISSN
IST-REx-ID
Cite this
Rinaldi P, Pérez-González PG, Rieke GH, et al. Deciphering the nature of Virgil: An obscured active galactic nucleus lurking within an apparently normal Lyα emitter during cosmic reionization. The Astrophysical Journal. 2025;994(1). doi:10.3847/1538-4357/ae089c
Rinaldi, P., Pérez-González, P. G., Rieke, G. H., Lyu, J., D’Eugenio, F., Wu, Z., … Zhu, Y. (2025). Deciphering the nature of Virgil: An obscured active galactic nucleus lurking within an apparently normal Lyα emitter during cosmic reionization. The Astrophysical Journal. IOP Publishing. https://doi.org/10.3847/1538-4357/ae089c
Rinaldi, Pierluigi, Pablo G. Pérez-González, George H. Rieke, Jianwei Lyu, Francesco D’Eugenio, Zihao Wu, Stefano Carniani, et al. “Deciphering the Nature of Virgil: An Obscured Active Galactic Nucleus Lurking within an Apparently Normal Lyα Emitter during Cosmic Reionization.” The Astrophysical Journal. IOP Publishing, 2025. https://doi.org/10.3847/1538-4357/ae089c.
P. Rinaldi et al., “Deciphering the nature of Virgil: An obscured active galactic nucleus lurking within an apparently normal Lyα emitter during cosmic reionization,” The Astrophysical Journal, vol. 994, no. 1. IOP Publishing, 2025.
Rinaldi P, Pérez-González PG, Rieke GH, Lyu J, D’Eugenio F, Wu Z, Carniani S, Looser TJ, Shivaei I, Boogaard LA, Diaz-Santos T, Colina L, Östlin G, Alberts S, Álvarez-Márquez J, Annuziatella M, Aravena M, Bhatawdekar R, Bunker AJ, Caputi KI, Charlot S, Crespo Gómez A, Curti M, Eckart A, Gillman S, Hainline K, Kumari N, Hjorth J, Iani E, Inami H, Ji Z, Johnson BD, Jones GC, Labiano Á, Maiolino R, Melinder J, Moutard T, Peissker F, Rieke M, Robertson B, Scholtz J, Tacchella S, Van Der Werf PP, Walter F, Williams CC, Willott C, Witstok J, Übler H, Zhu Y. 2025. Deciphering the nature of Virgil: An obscured active galactic nucleus lurking within an apparently normal Lyα emitter during cosmic reionization. The Astrophysical Journal. 994(1), 86.
Rinaldi, Pierluigi, et al. “Deciphering the Nature of Virgil: An Obscured Active Galactic Nucleus Lurking within an Apparently Normal Lyα Emitter during Cosmic Reionization.” The Astrophysical Journal, vol. 994, no. 1, 86, IOP Publishing, 2025, doi:10.3847/1538-4357/ae089c.
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