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

Abstract

JWST has revealed diverse new populations of high-redshift ($z\sim 4-11$) AGN and extreme star-forming galaxies that challenge current 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 AGN. From a parent sample of 205 ${\mathrm{z}}_{\mathrm{spec}}>3$ UNCOVER galaxies with NIRSpec/PRISM follow-up, we identify 12 C IV, He II, and C III] emitters. 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$\beta$ 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 ${\mathrm{M}}_{\ast }>2\times 10^9{\mathrm{M}}_{\odot }$ 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 $z>3$.

Accepted to ApJ

References in corpus (70)

• The Host Galaxies and Classification of Active Galactic Nuclei
• A luminous quasar at a redshift of z = 7.085
• The Co-Evolution of Galaxies and Supermassive Black Holes: Insights from Surveys of the Contemporary Universe
• The Near-Infrared Spectrograph (NIRSpec) on the James Webb Space Telescope I. Overview of the instrument and its capabilities
• Strong Nebular Line Ratios in the Spectra of z~2-3 Star-forming Galaxies: First Results from KBSS-MOSFIRE
• The James Webb Space Telescope Mission
• A Luminous Quasar at Redshift 7.642
• JADES NIRSpec Spectroscopy of GN-z11: Lyman-$\alpha$ emission and possible enhanced nitrogen abundance in a $z=10.60$ luminous galaxy
• The Pan-STARRS1 distant z>5.6 quasar survey: more than 100 quasars within the first Gyr of the universe
• A CEERS Discovery of an Accreting Supermassive Black Hole 570 Myr after the Big Bang: Identifying a Progenitor of Massive z > 6 Quasars
• JADES. The diverse population of infant Black Holes at 4<z<11: merging, tiny, poor, but mighty
• Modelling the nebular emission from primeval to present-day star-forming galaxies
• GA-NIFS: A massive black hole in a low-metallicity AGN at $z\sim 5.55$ revealed by JWST/NIRSpec IFS
• Hubble Space Telescope Combined Strong and Weak Lensing Analysis of the CLASH Sample: Mass and Magnification Models and Systematic Uncertainties
• Emission-line Diagnostics of Low Metallicity AGN
• Nebular Emission Line Ratios in z~2-3 Star-Forming Galaxies with KBSS-MOSFIRE: Exploring the Impact of Ionization, Excitation, and Nitrogen-to-Oxygen Ratio
• The MOSDEF Survey: Mass, Metallicity, and Star-formation Rate at z~2.3
• New insights into the stellar content and physical conditions of star-forming galaxies at z = 2-3 from spectral modelling
• Ultraviolet Emission Lines in Young Low Mass Galaxies at z~2: Physical Properties and Implications for Studies at z>7
• AGN Emission Line Diagnostics and the Mass-Metallicity Relation up to Redshift z~2: the Impact of Selection Effects and Evolution
• Ultraviolet spectra of extreme nearby star-forming regions --- approaching a local reference sample for JWST
• The Chemical Evolution of Carbon, Nitrogen, and Oxygen in Metal-Poor Dwarf Galaxies
• Diagnostics for PopIII galaxies and Direct Collapse Black Holes in the early universe
• The Physical Conditions of Emission-Line Galaxies at Cosmic Dawn from JWST/NIRSpec Spectroscopy in the SMACS 0723 Early Release Observations
• Evidence for a Hard Ionizing Spectrum from a z=6.11 Stellar Population
• JWST UNCOVER: Extremely red and compact object at$z_{\mathrm{phot}}\simeq 7.6$ triply imaged by Abell 2744
• A spectroscopic search for AGN activity in the reionization era
• A Candidate of a Least-Massive Black Hole at the First 1.1 Billion Years of the Universe
• UNCOVERing the extended strong lensing structures of Abell 2744 with the deepest JWST imaging
• Photoionization Models for the Semi-Forbidden C III] 1909 Emission in Star-Forming Galaxies
• Star formation histories of UV-luminous galaxies at $z\simeq 6.8$: implications for stellar mass assembly at early cosmic times
• EIGER V. Characterizing the Host Galaxies of Luminous Quasars at $z\gtrsim 6$
• The Low Mass End of the Fundamental Relation for Gravitationally Lensed Star Forming Galaxies at 1<z<6
• Extreme N-emitters at high-redshift: signatures of supermassive stars and globular cluster or black hole formation in action?
• CEERS Key Paper VI: JWST/MIRI Uncovers a Large Population of Obscured AGN at High Redshifts
• Synthetic nebular emission from massive galaxies I: origin of the cosmic evolution of optical emission-line ratios
• Galaxies hosting an AGN: a view from the CALIFA survey
• Morphologies of Galaxies at $z\gtrsim 9$ Uncovered by JWST/NIRCam Imaging: Cosmic Size Evolution and an Identification of an Extremely Compact Bright Galaxy at $z\sim 12$
• Trinity I: Self-Consistently Modeling the Dark Matter Halo-Galaxy-Supermassive Black Hole Connection from $z=0-10$
• Inferring More from Less: Prospector as a Photometric Redshift Engine in the Era of JWST
• Kinematics and Optical Depth in the Green Peas: Suppressed Superwinds in Candidate LyC Emitters
• [Ne V] Emission in Optically Classified Starbursts
• Obscured AGN at 1.5 < z < 3.0 from the zCOSMOS-deep Survey I. Properties of the emitting gas in the Narrow Line Region
• Strong Lyman continuum emitting galaxies show intense CIV 1550 emission
• Exploring HeII$\lambda$1640 emission line properties at $z\sim 2-4$
• The UNCOVER Survey: A First-look HST+JWST Catalog of Galaxy Redshifts and Stellar Population Properties Spanning $0.2\lesssim z\lesssim 15$
• Narrow He II emission in star-forming galaxies at low metallicity. Stellar wind emission from a population of Very Massive Stars
• CEERS Key Paper III: The Resolved Host Properties of AGN at 3 < z < 5 with JWST
• Searching for z > 6.5 Analogs Near the Peak of Cosmic Star Formation
• Using [Ne V]/[Ne III] to Understand the Nature of Extreme-Ionization Galaxies
• Assessing the sources of reionisation: a spectroscopic case study of a 30$\times$ lensed galaxy at $z\sim 5$ with Lyα, CIV, MgII, and [NeIII]
• Characterizing Extreme Emission Line Galaxies II: A Self-Consistent Model of Their Ionizing Spectrum
• Large Binocular Telescope observations of new six compact star-forming galaxies with [NeV] 3426A emission
• Nebular emission from young stellar populations including binary stars
• Strong C IV emission from star-forming galaxies: a case for high Lyman continuum photon escape
• The MUSE Hubble Ultra Deep Field Survey. XV. The mean rest-UV spectra of Ly-alpha emitters at z>3
• HST Emission Line Galaxies at z ~ 2: The Mystery of Neon
• Near-infrared emission line diagnostics for AGN from the local Universe to redshift 3
• Radio and Far-IR Emission Associated with a Massive Star-forming Galaxy Candidate at z$\simeq$6.8: A Radio-Loud AGN in the Reionization Era?
• Probing the $z\gtrsim 6$ quasars in a universe with IllustrisTNG physics: Impact of gas-based black hole seeding models
• Inferring the presence of very massive stars in local star-forming regions
• Evidence for Very Massive Stars in extremely UV-bright star-forming galaxies at $z\sim 2.2-3.6$
• Stromlo Stellar Tracks: non-solar scaled abundances for massive stars
• Recovery and analysis of rest-frame UV emission lines in 2052 galaxies observed with MUSE at $1.5<z<6.4$
• The Ionizing Spectra of Extremely Metal-Poor O Stars: Constraints from the Only HII Region in Leo P
• Extreme broad He\2 emission at high and low redshifts: the dominant role of VMS in NGC 3125-A1 and CDFS131717
• The Assembly of Black Hole Mass and Luminosity Functions of High-redshift Quasars via Multiple Accretion Episodes
• Astraeus VI: Hierarchical assembly of AGN and their large-scale effect during the Epoch of Reionization
• Insights into the reionization epoch from cosmic-noon-CIV emitters in the VANDELS survey
• Deciphering stellar metallicities in the early Universe: Case study of a young galaxy at z = 4.77 in the MUSE eXtremely Deep Field

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