_version_ 1866918237208313856
author Lin, Xiaojing
Fan, Xiaohui
Wang, Feige
Sun, Fengwu
Champagne, Jaclyn B.
Egami, Eiichi
Kakiichi, Koki
Lyu, Jianwei
Tee, Wei Leong
Yang, Jinyi
Bian, Fuyan
Bosman, Sarah E. I.
Cai, Zheng
Casey, Caitlin M.
Decarli, Roberto
Faisst, Andreas L.
Fujimoto, Seiji
Harish, Santosh
Ilbert, Olivier
Inoue, Akio K.
Jin, Xiangyu
Kartaltepe, Jeyhan S.
Kocevski, Dale D.
Li, Mingyu
Liu, Weizhe
Liu, Yichen
Schindler, Jan-Torge
Shuntov, Marko
Tanaka, Takumi S.
Vestergaard, Marianne
Wu, Yunjing
Zhang, Haowen
Zhang, Zijian
author_facet Lin, Xiaojing
Fan, Xiaohui
Wang, Feige
Sun, Fengwu
Champagne, Jaclyn B.
Egami, Eiichi
Kakiichi, Koki
Lyu, Jianwei
Tee, Wei Leong
Yang, Jinyi
Bian, Fuyan
Bosman, Sarah E. I.
Cai, Zheng
Casey, Caitlin M.
Decarli, Roberto
Faisst, Andreas L.
Fujimoto, Seiji
Harish, Santosh
Ilbert, Olivier
Inoue, Akio K.
Jin, Xiangyu
Kartaltepe, Jeyhan S.
Kocevski, Dale D.
Li, Mingyu
Liu, Weizhe
Liu, Yichen
Schindler, Jan-Torge
Shuntov, Marko
Tanaka, Takumi S.
Vestergaard, Marianne
Wu, Yunjing
Zhang, Haowen
Zhang, Zijian
contents We report the discovery of 13 broad-line AGNs at $z = 5 - 8$ from the first 10% data of the JWST Cycle 3 Treasury Program COSMOS-3D. These AGNs are identified by their broad H$α$ or H$β$ emission lines through the NIRCam grism wide-field slitless spectroscopy. One object at $z = 7.646$ with broad H$β$ emission has an F444W magnitude of 23.6 mag, making it one of the brightest $z > 7.5$ broad-line AGNs yet known. Among the 13 AGNs, 10 objects have reddened optical continua with slopes $β_{\rm opt}>0$. The remaining three objects have their overall SEDs that resemble those of UV-luminous quasars at similar redshifts, but their $β_{\rm opt}$, though negative, are not as blue as those of unobscured quasars. We also obtain MIRI photometry at 7.7-18 $μ$m for two AGNs and place strong constraints on their rest-frame near-IR SED. We find no significant variability in the rest-frame UV by comparing the COSMOS-3D and COSMOS-Web F115W images taken apart by 60 days in the rest-frame. We compute the H$α$ luminosity functions (LFs) for the broad H$α$ emitters at $z \approx 5-6$ and find a potential redshift evolution when compared with that of the $z \approx 4-5$ sample. We also derive the H$β$ LF at $z\sim8$ for AGNs and galaxies by combining our sample with those from the literature. The broad H$β$ emitters in this work suggest a number density two orders of magnitude higher than that predicted by the quasar LF based on rest-frame UV-selected samples. As a preview, our work showcases the ability of the COSMOS-3D grism survey to provide a complete view of the properties, growth, and evolution of bright broad-line AGNs at $z>5$.
format Preprint
id arxiv_https___arxiv_org_abs_2504_08039
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Bridging Quasars and Little Red Dots: Insights into Broad-Line AGNs at $z=5-8$ from the First JWST COSMOS-3D Dataset
Lin, Xiaojing
Fan, Xiaohui
Wang, Feige
Sun, Fengwu
Champagne, Jaclyn B.
Egami, Eiichi
Kakiichi, Koki
Lyu, Jianwei
Tee, Wei Leong
Yang, Jinyi
Bian, Fuyan
Bosman, Sarah E. I.
Cai, Zheng
Casey, Caitlin M.
Decarli, Roberto
Faisst, Andreas L.
Fujimoto, Seiji
Harish, Santosh
Ilbert, Olivier
Inoue, Akio K.
Jin, Xiangyu
Kartaltepe, Jeyhan S.
Kocevski, Dale D.
Li, Mingyu
Liu, Weizhe
Liu, Yichen
Schindler, Jan-Torge
Shuntov, Marko
Tanaka, Takumi S.
Vestergaard, Marianne
Wu, Yunjing
Zhang, Haowen
Zhang, Zijian
Astrophysics of Galaxies
We report the discovery of 13 broad-line AGNs at $z = 5 - 8$ from the first 10% data of the JWST Cycle 3 Treasury Program COSMOS-3D. These AGNs are identified by their broad H$α$ or H$β$ emission lines through the NIRCam grism wide-field slitless spectroscopy. One object at $z = 7.646$ with broad H$β$ emission has an F444W magnitude of 23.6 mag, making it one of the brightest $z > 7.5$ broad-line AGNs yet known. Among the 13 AGNs, 10 objects have reddened optical continua with slopes $β_{\rm opt}>0$. The remaining three objects have their overall SEDs that resemble those of UV-luminous quasars at similar redshifts, but their $β_{\rm opt}$, though negative, are not as blue as those of unobscured quasars. We also obtain MIRI photometry at 7.7-18 $μ$m for two AGNs and place strong constraints on their rest-frame near-IR SED. We find no significant variability in the rest-frame UV by comparing the COSMOS-3D and COSMOS-Web F115W images taken apart by 60 days in the rest-frame. We compute the H$α$ luminosity functions (LFs) for the broad H$α$ emitters at $z \approx 5-6$ and find a potential redshift evolution when compared with that of the $z \approx 4-5$ sample. We also derive the H$β$ LF at $z\sim8$ for AGNs and galaxies by combining our sample with those from the literature. The broad H$β$ emitters in this work suggest a number density two orders of magnitude higher than that predicted by the quasar LF based on rest-frame UV-selected samples. As a preview, our work showcases the ability of the COSMOS-3D grism survey to provide a complete view of the properties, growth, and evolution of bright broad-line AGNs at $z>5$.
title Bridging Quasars and Little Red Dots: Insights into Broad-Line AGNs at $z=5-8$ from the First JWST COSMOS-3D Dataset
topic Astrophysics of Galaxies
url https://arxiv.org/abs/2504.08039