SHELLQs. Bridging the Gap: JWST Unveils Obscured Quasars in the Most Luminous Galaxies at <i>z </i> &gt; 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 &gt; 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 &gt;1000 deg 2 , and were known to have luminous (&gt;10 43 erg s −1 ) Ly α emission. With JWST/NIRSpec follow-up observations, we found that 7 out of 11 objects with narrow Ly α 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 &lt; A V &lt; 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 M ⊙ , 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 α emitters to be larger than 2 × 10 −8 Mpc −3 . 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.

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Publication Details

Journal
The Astrophysical Journal
Published
2025-07-14
DOI
https://doi.org/10.3847/1538-4357/addf4e
Citations
7
Primary Topic
Galaxies: Formation, Evolution, Phenomena
Type
article
Field-Weighted Citation Impact
8.08

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article

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

Takuma Izumi, Camryn L. Phillips, Xuheng Ding, Kentaro Aoki et al.
7 citations
The Astrophysical Journal
Galaxies: Formation, Evolution, Phenomena
8.08
article

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

Takuma Izumi, Camryn L. Phillips, Xuheng Ding, Kentaro Aoki, Toshihiro Kawaguchi, Ayumi Takahashi, Masafusa Onoue, Satoshi Kikuta, Nobunari Kashikawa, Chien‐Hsiu Lee, J. D. Silverman, Michael A. Strauss, Tohru Nagao, Yoshiki Toba, Yoshiki Matsuoka, Masatoshi Imanishi, Masayuki Akiyama, Kotaro Kohno, Junya Arita, K. Iwasawa
article en
7 citations

Abstract

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 &gt; 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 &gt;1000 deg 2 , and were known to have luminous (&gt;10 43 erg s −1 ) Ly α emission. With JWST/NIRSpec follow-up observations, we found that 7 out of 11 objects with narrow Ly α 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 &lt; A V &lt; 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 M ⊙ , 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 α emitters to be larger than 2 × 10 −8 Mpc −3 . 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.

The Astrophysical JournalVol. 988(1)
Institute of Astronomy and Astrophysics, Academia Sinica (TW), Ritsumeikan University (JP), Johns Hopkins University (US), Waseda University (JP), Kavli Institute for the Physics and Mathematics of the Universe (JP), The Graduate University for Advanced Studies, SOKENDAI (JP), Princeton University (US), Tohoku University (JP), Peking University (CN), Wuhan University (CN), Kavli Institute for Theoretical Sciences (CN), CTA Observatory (IT), National Astronomical Observatory of Japan (JP), University of Toyama (JP), Ehime University (JP), Universitat de Barcelona (ES), The University of Tokyo (JP)
Ministerio de Ciencia e Innovación
Openalex Percentile: Top 3%
Galaxies: Formation, Evolution, Phenomena
8.08
DOIOpen Access PDFOpenAlex
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