UNCOVERing the High-redshift AGN Population among Extreme UV Line Emitters

JWST has revealed diverse new populations of high-redshift ( z  ∼ 4–11) active galactic nuclei (AGNs) and extreme star-forming galaxies that challenge current photoionization models. In this paper, we use rest-frame UV emission-line diagnostics to identify AGN candidates and other exceptional ionizi...

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Main Authors: Helena Treiber, Jenny E. Greene, John R. Weaver, Tim B. Miller, Lukas J. Furtak, David J. Setton, Bingjie Wang, Anna de Graaff, Rachel Bezanson, Gabriel Brammer, Sam E. Cutler, Pratika Dayal, Robert Feldmann, Seiji Fujimoto, Andy D. Goulding, Vasily Kokorev, Ivo Labbe, Joel Leja, Danilo Marchesini, Themiya Nanayakkara, Erica Nelson, Richard Pan, Sedona H. Price, Jared Siegel, Katherine A. Suess, Katherine E. Whitaker
Format: Article
Language:English
Published: IOP Publishing 2025-01-01
Series:The Astrophysical Journal
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Online Access:https://doi.org/10.3847/1538-4357/adc38f
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author Helena Treiber
Jenny E. Greene
John R. Weaver
Tim B. Miller
Lukas J. Furtak
David J. Setton
Bingjie Wang
Anna de Graaff
Rachel Bezanson
Gabriel Brammer
Sam E. Cutler
Pratika Dayal
Robert Feldmann
Seiji Fujimoto
Andy D. Goulding
Vasily Kokorev
Ivo Labbe
Joel Leja
Danilo Marchesini
Themiya Nanayakkara
Erica Nelson
Richard Pan
Sedona H. Price
Jared Siegel
Katherine A. Suess
Katherine E. Whitaker
author_facet Helena Treiber
Jenny E. Greene
John R. Weaver
Tim B. Miller
Lukas J. Furtak
David J. Setton
Bingjie Wang
Anna de Graaff
Rachel Bezanson
Gabriel Brammer
Sam E. Cutler
Pratika Dayal
Robert Feldmann
Seiji Fujimoto
Andy D. Goulding
Vasily Kokorev
Ivo Labbe
Joel Leja
Danilo Marchesini
Themiya Nanayakkara
Erica Nelson
Richard Pan
Sedona H. Price
Jared Siegel
Katherine A. Suess
Katherine E. Whitaker
author_sort Helena Treiber
collection DOAJ
description JWST has revealed diverse new populations of high-redshift ( z  ∼ 4–11) active galactic nuclei (AGNs) and extreme star-forming galaxies that challenge current photoionization models. In this paper, we use rest-frame UV emission-line diagnostics to identify AGN candidates and other exceptional ionizing sources, complementing previous studies predominantly focused on broad-line AGNs. From a parent sample of 205 z _spec  > 3 UNCOVER galaxies with NIRSpec/PRISM follow-up, we identify 12 galaxies with C IV , He II , and/or C III ] emission. Three of these galaxies also exhibit clear N III ] and/or N IV ] lines. Leveraging the combined rest-optical and UV coverage of PRISM, we limit the emission-line model space using the sample’s [O III ]/H β distribution, significantly decreasing the overlap between AGN and star formation models in the UV diagnostics. We then find that the five He II emitters are the strongest AGN candidates, with further support from two [Ne v ] detections and one X-ray detection from Chandra. Our Balmer line fits also reveal one new broad-line AGN at z = 6.87. We cannot robustly quantify the AGN fraction in this sample, but we note that close to 20% of M _*  > 2 × 10 ^9 M _⊙ parent sample galaxies are AGN candidates. The lower-mass line emitters, which are consistent with both AGN and star-forming photoionization models, have more compact sizes and higher specific star formation rates than the parent sample. Higher-resolution and deeper data on these UV line emitters should provide much stronger constraints on the obscured AGN fraction at z  > 3.
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spelling doaj-art-e9e6e12a10a941feb033da4fc2f607be2025-08-20T02:28:55ZengIOP PublishingThe Astrophysical Journal1538-43572025-01-0198419310.3847/1538-4357/adc38fUNCOVERing the High-redshift AGN Population among Extreme UV Line EmittersHelena Treiber0https://orcid.org/0000-0003-0660-9776Jenny E. Greene1https://orcid.org/0000-0002-5612-3427John R. Weaver2https://orcid.org/0000-0003-1614-196XTim B. Miller3https://orcid.org/0000-0001-8367-6265Lukas J. Furtak4https://orcid.org/0000-0001-6278-032XDavid J. Setton5https://orcid.org/0000-0003-4075-7393Bingjie Wang6https://orcid.org/0000-0001-9269-5046Anna de Graaff7https://orcid.org/0000-0002-2380-9801Rachel Bezanson8https://orcid.org/0000-0001-5063-8254Gabriel Brammer9https://orcid.org/0000-0003-2680-005XSam E. Cutler10https://orcid.org/0000-0002-7031-2865Pratika Dayal11https://orcid.org/0000-0001-8460-1564Robert Feldmann12https://orcid.org/0000-0002-1109-1919Seiji Fujimoto13https://orcid.org/0000-0001-7201-5066Andy D. Goulding14https://orcid.org/0000-0003-4700-663XVasily Kokorev15https://orcid.org/0000-0002-5588-9156Ivo Labbe16https://orcid.org/0000-0002-2057-5376Joel Leja17https://orcid.org/0000-0001-6755-1315Danilo Marchesini18https://orcid.org/0000-0001-9002-3502Themiya Nanayakkara19https://orcid.org/0000-0003-2804-0648Erica Nelson20https://orcid.org/0000-0002-7524-374XRichard Pan21https://orcid.org/0000-0002-9651-5716Sedona H. Price22https://orcid.org/0000-0002-0108-4176Jared Siegel23https://orcid.org/0000-0002-9337-0902Katherine A. Suess24https://orcid.org/0000-0002-1714-1905Katherine E. Whitaker25https://orcid.org/0000-0001-7160-3632Department of Astrophysical Sciences, Princeton University , 4 Ivy Lane, Princeton, NJ 08544, USA ; lena.treiber@princeton.eduDepartment of Astrophysical Sciences, Princeton University , 4 Ivy Lane, Princeton, NJ 08544, USA ; lena.treiber@princeton.eduDepartment of Astronomy, University of Massachusetts , Amherst, MA 01003, USACenter for Interdisciplinary Exploration and Research in Astrophysics (CIERA) and Department of Physics & Astronomy, Northwestern University , IL 60201, USADepartment of Physics, Ben-Gurion University of the Negev , P.O. Box 653, Beer-Sheva 8410501, IsraelDepartment of Astrophysical Sciences, Princeton University , 4 Ivy Lane, Princeton, NJ 08544, USA ; lena.treiber@princeton.eduDepartment of Astronomy & Astrophysics, The Pennsylvania State University , University Park, PA 16802, USA; Institute for Computational & Data Sciences, The Pennsylvania State University , University Park, PA 16802, USA; Institute for Gravitation and the Cosmos, The Pennsylvania State University , University Park, PA 16802, USAMax-Planck-Institut für Astronomie , Königstuhl 17, D-69117, Heidelberg, GermanyDepartment of Physics & Astronomy and PITT PACC, University of Pittsburgh , Pittsburgh, PA 15260, USACosmic Dawn Center (DAWN), Niels Bohr Institute, University of Copenhagen , Jagtvej 128, København N, DK-2200, DenmarkDepartment of Astronomy, University of Massachusetts , Amherst, MA 01003, USAKapteyn Astronomical Institute, University of Groningen , P.O. Box 800, 9700 AV Groningen, The NetherlandsDepartment of Astrophysics, University of Zurich , Winterthurerstrasse 190, CH-8057 Zurich, SwitzerlandDepartment of Astronomy, The University of Texas at Austin , Austin, TX 78712, USADepartment of Astrophysical Sciences, Princeton University , 4 Ivy Lane, Princeton, NJ 08544, USA ; lena.treiber@princeton.eduKapteyn Astronomical Institute, University of Groningen , P.O. Box 800, 9700 AV Groningen, The NetherlandsCentre for Astrophysics and Supercomputing, Swinburne University of Technology , Melbourne, VIC 3122, AustraliaDepartment of Astronomy & Astrophysics, The Pennsylvania State University , University Park, PA 16802, USA; Institute for Computational & Data Sciences, The Pennsylvania State University , University Park, PA 16802, USA; Institute for Gravitation and the Cosmos, The Pennsylvania State University , University Park, PA 16802, USADepartment of Physics & Astronomy, Tufts University , MA 02155, USACentre for Astrophysics and Supercomputing, Swinburne University of Technology , PO Box 218, Hawthorn, VIC 3122, AustraliaDepartment for Astrophysical and Planetary Science, University of Colorado , Boulder, CO 80309, USADepartment of Physics & Astronomy, Tufts University , 574 Boston Avenue, Medford, MA 02155, USADepartment of Physics & Astronomy and PITT PACC, University of Pittsburgh , Pittsburgh, PA 15260, USADepartment of Astrophysical Sciences, Princeton University , 4 Ivy Lane, Princeton, NJ 08544, USA ; lena.treiber@princeton.eduKavli Institute for Particle Astrophysics and Cosmology and Department of Physics, Stanford University , Stanford, CA 94305, USADepartment of Astronomy, University of Massachusetts , Amherst, MA 01003, USA; Cosmic Dawn Center (DAWN) , DenmarkJWST has revealed diverse new populations of high-redshift ( z  ∼ 4–11) active galactic nuclei (AGNs) and extreme star-forming galaxies that challenge current photoionization models. In this paper, we use rest-frame UV emission-line diagnostics to identify AGN candidates and other exceptional ionizing sources, complementing previous studies predominantly focused on broad-line AGNs. From a parent sample of 205 z _spec  > 3 UNCOVER galaxies with NIRSpec/PRISM follow-up, we identify 12 galaxies with C IV , He II , and/or C III ] emission. Three of these galaxies also exhibit clear N III ] and/or N IV ] lines. Leveraging the combined rest-optical and UV coverage of PRISM, we limit the emission-line model space using the sample’s [O III ]/H β distribution, significantly decreasing the overlap between AGN and star formation models in the UV diagnostics. We then find that the five He II emitters are the strongest AGN candidates, with further support from two [Ne v ] detections and one X-ray detection from Chandra. Our Balmer line fits also reveal one new broad-line AGN at z = 6.87. We cannot robustly quantify the AGN fraction in this sample, but we note that close to 20% of M _*  > 2 × 10 ^9 M _⊙ parent sample galaxies are AGN candidates. The lower-mass line emitters, which are consistent with both AGN and star-forming photoionization models, have more compact sizes and higher specific star formation rates than the parent sample. Higher-resolution and deeper data on these UV line emitters should provide much stronger constraints on the obscured AGN fraction at z  > 3.https://doi.org/10.3847/1538-4357/adc38fActive galactic nucleiHigh-redshift galaxiesEarly universeEmission line galaxies
spellingShingle Helena Treiber
Jenny E. Greene
John R. Weaver
Tim B. Miller
Lukas J. Furtak
David J. Setton
Bingjie Wang
Anna de Graaff
Rachel Bezanson
Gabriel Brammer
Sam E. Cutler
Pratika Dayal
Robert Feldmann
Seiji Fujimoto
Andy D. Goulding
Vasily Kokorev
Ivo Labbe
Joel Leja
Danilo Marchesini
Themiya Nanayakkara
Erica Nelson
Richard Pan
Sedona H. Price
Jared Siegel
Katherine A. Suess
Katherine E. Whitaker
UNCOVERing the High-redshift AGN Population among Extreme UV Line Emitters
The Astrophysical Journal
Active galactic nuclei
High-redshift galaxies
Early universe
Emission line galaxies
title UNCOVERing the High-redshift AGN Population among Extreme UV Line Emitters
title_full UNCOVERing the High-redshift AGN Population among Extreme UV Line Emitters
title_fullStr UNCOVERing the High-redshift AGN Population among Extreme UV Line Emitters
title_full_unstemmed UNCOVERing the High-redshift AGN Population among Extreme UV Line Emitters
title_short UNCOVERing the High-redshift AGN Population among Extreme UV Line Emitters
title_sort uncovering the high redshift agn population among extreme uv line emitters
topic Active galactic nuclei
High-redshift galaxies
Early universe
Emission line galaxies
url https://doi.org/10.3847/1538-4357/adc38f
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