SHELLQs. Bridging the Gap: JWST Unveils Obscured Quasars in the Most Luminous Galaxies at z > 6

Abstract

The unprecedented sensitivity of the James Webb Space Telescope (JWST) has uncovered a surprisingly abundant population of mildly obscured, low-luminosity active galactic nuclei (AGNs) in the epoch of reionization (EoR). However, the link between these objects and classical unobscured quasars remains a mystery. Here we report the discovery of obscured quasars hosted by the most luminous galaxies at z > 6, possibly bridging the gap between the two AGN populations. The 13 objects presented here were originally selected from a rest-frame ultraviolet (UV) imaging survey over >1000 deg2, and were known to have luminous (>10^{43} erg/s) narrow Ly-alpha emission. With JWST/NIRSpec follow-up observations, we found that 7 out of 11 objects with narrow Ly-alpha exhibit a broad component in H I Balmer lines and He I lines, but not in [O III] and other forbidden lines. Mild dust obscuration (0 < Av < 3) is inferred from the Balmer decrements. The estimated intrinsic luminosities suggest that our broad line (BL) objects are the long-sought UV-obscured counterparts of luminous quasars in the EoR. They host supermassive black holes (SMBHs) with masses 10^(7.8-9.1) Msun, undergoing sub-Eddington to Eddington accretion. Most of the BL objects are spatially unresolved, and are close to "little red dots" with their blue rest-UV and red rest-optical colors. We estimate the AGN number density among similarly luminous Ly-alpha emitters to be larger than 2 x 10^(-8) /Mpc3. This density is comparable to that of classical quasars with similar continuum luminosities, suggesting that a substantial fraction of active SMBHs are obscured in the EoR and have been overlooked in past rest-UV surveys.

Published in ApJ

References in corpus (46)

• A Catalog of Quasar Properties from SDSS DR7
• The Co-Evolution of Galaxies and Supermassive Black Holes: Insights from Surveys of the Contemporary Universe
• A population of red candidate massive galaxies ~600 Myr after the Big Bang
• CEERS Key Paper I: An Early Look into the First 500 Myr of Galaxy Formation with JWST
• 3D Lyman-alpha radiation transfer. I. Understanding Lyman-alpha line profile morphologies
• The Science Performance of JWST as Characterized in Commissioning
• New Determinations of the UV Luminosity Functions from z~9 to z~2 show a remarkable consistency with halo growth and a constant star formation efficiency
• A CEERS Discovery of an Accreting Supermassive Black Hole 570 Myr after the Big Bang: Identifying a Progenitor of Massive z > 6 Quasars
• Third Data Release of the Hyper Suprime-Cam Subaru Strategic Program
• JADES. The diverse population of infant Black Holes at 4<z<11: merging, tiny, poor, but mighty
• Early results from GLASS-JWST. III: Galaxy candidates at z$\sim$9-15
• 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
• Spectroscopic confirmation of two luminous galaxies at $z\sim 14$
• Fe II Emission in 14 Low-Redshift Quasars: I - Observations
• A massive quiescent galaxy at redshift 4.658
• Rapidly star-forming galaxies adjacent to quasars at redshifts exceeding 6
• RUBIES: Evolved Stellar Populations with Extended Formation Histories at $z\sim 7-8$ in Candidate Massive Galaxies Identified with JWST/NIRSpec
• Diagnostics for PopIII galaxies and Direct Collapse Black Holes in the early universe
• Detection of stellar light from quasar host galaxies at redshifts above 6
• A Candidate of a Least-Massive Black Hole at the First 1.1 Billion Years of the Universe
• A dormant, overmassive black hole in the early Universe
• Deciphering the JWST spectrum of a 'little red dot' at $z\sim 4.53$: An obscured AGN and its star-forming host
• Mildly Super-Eddington Accretion Onto Slowly-Spinning Black Holes Explains the X-Ray Weakness of the Little Red Dots
• JADES: A large population of obscured, narrow line AGN at high redshift
• Subaru High-z Exploration of Low-Luminosity Quasars (SHELLQs). XIII. Large-scale Feedback and Star Formation in a Low-Luminosity Quasar at z = 7.07 on the Local Black Hole to Host Mass Relation
• RUBIES: JWST/NIRSpec Confirmation of an Infrared-luminous, Broad-line Little Red Dot with an Ionized Outflow
• The SINS Survey: Broad Emission Lines in High-Redshift Star-Forming Galaxies
• A SPectroscopic survey of biased halos In the Reionization Era (ASPIRE): A First Look at the Rest-frame Optical Spectra of $z>6.5$ Quasars Using JWST
• New AGN diagnostic diagrams based on the [OIII]$\lambda 4363$ auroral line
• Quasar Luminosity Function at z = 7
• Observations of OI and CaII Emission Lines in Quasars: Implications for the Site of FeII Line Emission
• The eventful life of a luminous galaxy at z = 14: metal enrichment, feedback, and low gas fraction?
• UNCOVER: 404 Error -- Models Not Found for the Triply Imaged Little Red Dot A2744-QSO1
• How does the Polar Dust affect the Correlation between Dust Covering Factor and Eddington Ratio in Type 1 Quasars Selected from the Sloan Digital Sky Survey Data Release 16?
• J-PLUS: Unveiling the brightest-end of the Lyα luminosity function at 2.0<z<3.3 over 1000 deg^2
• Deep silence: radio properties of little red dots
• Subaru High-z Exploration of Low-Luminosity Quasars (SHELLQs) XII. Extended [C II] Structure (Merger or Outflow) in a z = 6.72 Red Quasar
• Physical properties of extreme emission-line galaxies at $z\sim 4-9$ from the JWST CEERS survey
• Near Infrared Spectra and Intrinsic Luminosities of Candidate Type II Quasars at 2 < z < 3.4
• Subaru High-z Exploration of Low-Luminosity Quasars (SHELLQs). IX. Identification of Two Red Quasars at z > 5.6
• Discovery of merging twin quasars at z = 6.05
• CHORUS. I. Cosmic HydrOgen Reionization Unveiled with Subaru: Overview
• A Big Red Dot: Scattered light, host galaxy signatures and multi-phase gas flows in a luminous, heavily reddened quasar at cosmic noon
• Testing the paradigm: First spectroscopic evidence of a quasar-galaxy Mpc-scale association at cosmic dawn
• Fading Light, Fierce Winds: JWST Snapshot of a Sub-Eddington Quasar at Cosmic Dawn

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• A big red dot at cosmic noon
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• A first look at quasar-galaxy clustering at $z\simeq 7.3$