A JWST/NIRSpec First Census of Broad-line AGNs at z = 4–7: Detection of 10 Faint AGNs with M BH ∼ 106–108 M ⊙ and Their Host Galaxy Properties
We present the first statistical sample of faint type 1 AGNs at z > 4 identified by JWST/NIRSpec deep spectroscopy. Among the 185 galaxies at z _spec = 3.8–8.9 confirmed with NIRSpec, our systematic search for broad-line emission reveals 10 type 1 AGNs at z = 4.015–6.936 whose broad component is...
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| Format: | Article |
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IOP Publishing
2023-01-01
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| Series: | The Astrophysical Journal |
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| Online Access: | https://doi.org/10.3847/1538-4357/ad029e |
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| author | Yuichi Harikane Yechi Zhang Kimihiko Nakajima Masami Ouchi Yuki Isobe Yoshiaki Ono Shun Hatano Yi Xu Hiroya Umeda |
| author_facet | Yuichi Harikane Yechi Zhang Kimihiko Nakajima Masami Ouchi Yuki Isobe Yoshiaki Ono Shun Hatano Yi Xu Hiroya Umeda |
| author_sort | Yuichi Harikane |
| collection | DOAJ |
| description | We present the first statistical sample of faint type 1 AGNs at z > 4 identified by JWST/NIRSpec deep spectroscopy. Among the 185 galaxies at z _spec = 3.8–8.9 confirmed with NIRSpec, our systematic search for broad-line emission reveals 10 type 1 AGNs at z = 4.015–6.936 whose broad component is only seen in the permitted H α line and not in the forbidden [O iii ] λ 5007 line that is detected with greater significance than H α . The broad H α line widths of FWHM ≃ 1000–6000 km s ^−1 suggest that the AGNs have low-mass black holes with M _BH ∼ 10 ^6 –10 ^8 M _⊙ , remarkably lower than those of low-luminosity quasars previously identified at z > 4 with ground-based telescopes. JWST and Hubble Space Telescope high-resolution images reveal that the majority of them show extended morphologies indicating significant contribution to the total lights from their host galaxies, except for three compact objects two of which show red spectral energy distributions, probably in a transition phase from faint AGNs to low luminosity quasars. Careful AGN-host decomposition analyses show that their host’s stellar masses are systematically lower than the local relation between the black hole mass and the stellar mass, implying a fast black hole growth consistent with predictions from theoretical simulations. A high fraction of the broad-line AGNs (∼5%), higher than z ∼ 0, indicates that the number density of such faint AGNs is higher than an extrapolation of the quasar luminosity function, implying a large population of AGNs in the early universe. Such faint AGNs contribute to cosmic reionization, while the total contribution is not large, up to ∼50% at z ∼ 6, because of their faint nature. |
| first_indexed | 2024-03-09T02:44:39Z |
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| issn | 1538-4357 |
| language | English |
| last_indexed | 2024-03-09T02:44:39Z |
| publishDate | 2023-01-01 |
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| spelling | doaj.art-d0fe3ad83ca64d50b841f9f88e6df1952023-12-05T20:57:13ZengIOP PublishingThe Astrophysical Journal1538-43572023-01-0195913910.3847/1538-4357/ad029eA JWST/NIRSpec First Census of Broad-line AGNs at z = 4–7: Detection of 10 Faint AGNs with M BH ∼ 106–108 M ⊙ and Their Host Galaxy PropertiesYuichi Harikane0https://orcid.org/0000-0002-6047-430XYechi Zhang1https://orcid.org/0000-0003-3817-8739Kimihiko Nakajima2https://orcid.org/0000-0003-2965-5070Masami Ouchi3https://orcid.org/0000-0002-1049-6658Yuki Isobe4https://orcid.org/0000-0001-7730-8634Yoshiaki Ono5https://orcid.org/0000-0001-9011-7605Shun Hatano6https://orcid.org/0000-0002-5816-4660Yi Xu7https://orcid.org/0000-0002-5768-8235Hiroya Umeda8https://orcid.org/0009-0008-0167-5129Institute for Cosmic Ray Research, The University of Tokyo , 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8582, Japan ; hari@icrr.u-tokyo.ac.jpInstitute for Cosmic Ray Research, The University of Tokyo , 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8582, Japan ; hari@icrr.u-tokyo.ac.jp; Department of Astronomy, Graduate School of Science, The University of Tokyo , 7-3-1 Hongo, Bunkyo, Tokyo 113-0033, JapanNational Astronomical Observatory of Japan , 2-21-1 Osawa, Mitaka, Tokyo 181-8588, JapanInstitute for Cosmic Ray Research, The University of Tokyo , 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8582, Japan ; hari@icrr.u-tokyo.ac.jp; National Astronomical Observatory of Japan , 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan; Kavli Institute for the Physics and Mathematics of the Universe (WPI), University of Tokyo , Kashiwa, Chiba 277-8583, JapanInstitute for Cosmic Ray Research, The University of Tokyo , 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8582, Japan ; hari@icrr.u-tokyo.ac.jp; Department of Physics, Graduate School of Science, The University of Tokyo , 7-3-1 Hongo, Bunkyo, Tokyo 113-0033, JapanInstitute for Cosmic Ray Research, The University of Tokyo , 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8582, Japan ; hari@icrr.u-tokyo.ac.jpNational Astronomical Observatory of Japan , 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan; Department of Astronomical Science, The Graduate University for Advanced Studies , SOKENDAI, 2-21-1 Osawa, Mitaka, Tokyo, 181-8588, JapanInstitute for Cosmic Ray Research, The University of Tokyo , 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8582, Japan ; hari@icrr.u-tokyo.ac.jp; Department of Astronomy, Graduate School of Science, The University of Tokyo , 7-3-1 Hongo, Bunkyo, Tokyo 113-0033, JapanInstitute for Cosmic Ray Research, The University of Tokyo , 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8582, Japan ; hari@icrr.u-tokyo.ac.jp; Department of Physics, Graduate School of Science, The University of Tokyo , 7-3-1 Hongo, Bunkyo, Tokyo 113-0033, JapanWe present the first statistical sample of faint type 1 AGNs at z > 4 identified by JWST/NIRSpec deep spectroscopy. Among the 185 galaxies at z _spec = 3.8–8.9 confirmed with NIRSpec, our systematic search for broad-line emission reveals 10 type 1 AGNs at z = 4.015–6.936 whose broad component is only seen in the permitted H α line and not in the forbidden [O iii ] λ 5007 line that is detected with greater significance than H α . The broad H α line widths of FWHM ≃ 1000–6000 km s ^−1 suggest that the AGNs have low-mass black holes with M _BH ∼ 10 ^6 –10 ^8 M _⊙ , remarkably lower than those of low-luminosity quasars previously identified at z > 4 with ground-based telescopes. JWST and Hubble Space Telescope high-resolution images reveal that the majority of them show extended morphologies indicating significant contribution to the total lights from their host galaxies, except for three compact objects two of which show red spectral energy distributions, probably in a transition phase from faint AGNs to low luminosity quasars. Careful AGN-host decomposition analyses show that their host’s stellar masses are systematically lower than the local relation between the black hole mass and the stellar mass, implying a fast black hole growth consistent with predictions from theoretical simulations. A high fraction of the broad-line AGNs (∼5%), higher than z ∼ 0, indicates that the number density of such faint AGNs is higher than an extrapolation of the quasar luminosity function, implying a large population of AGNs in the early universe. Such faint AGNs contribute to cosmic reionization, while the total contribution is not large, up to ∼50% at z ∼ 6, because of their faint nature.https://doi.org/10.3847/1538-4357/ad029eGalaxy formationGalaxy evolutionAGN host galaxiesActive galactic nuclei |
| spellingShingle | Yuichi Harikane Yechi Zhang Kimihiko Nakajima Masami Ouchi Yuki Isobe Yoshiaki Ono Shun Hatano Yi Xu Hiroya Umeda A JWST/NIRSpec First Census of Broad-line AGNs at z = 4–7: Detection of 10 Faint AGNs with M BH ∼ 106–108 M ⊙ and Their Host Galaxy Properties The Astrophysical Journal Galaxy formation Galaxy evolution AGN host galaxies Active galactic nuclei |
| title | A JWST/NIRSpec First Census of Broad-line AGNs at z = 4–7: Detection of 10 Faint AGNs with M BH ∼ 106–108 M ⊙ and Their Host Galaxy Properties |
| title_full | A JWST/NIRSpec First Census of Broad-line AGNs at z = 4–7: Detection of 10 Faint AGNs with M BH ∼ 106–108 M ⊙ and Their Host Galaxy Properties |
| title_fullStr | A JWST/NIRSpec First Census of Broad-line AGNs at z = 4–7: Detection of 10 Faint AGNs with M BH ∼ 106–108 M ⊙ and Their Host Galaxy Properties |
| title_full_unstemmed | A JWST/NIRSpec First Census of Broad-line AGNs at z = 4–7: Detection of 10 Faint AGNs with M BH ∼ 106–108 M ⊙ and Their Host Galaxy Properties |
| title_short | A JWST/NIRSpec First Census of Broad-line AGNs at z = 4–7: Detection of 10 Faint AGNs with M BH ∼ 106–108 M ⊙ and Their Host Galaxy Properties |
| title_sort | jwst nirspec first census of broad line agns at z 4 7 detection of 10 faint agns with m bh ∼ 106 108 m ⊙ and their host galaxy properties |
| topic | Galaxy formation Galaxy evolution AGN host galaxies Active galactic nuclei |
| url | https://doi.org/10.3847/1538-4357/ad029e |
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