_version_ 1866908604055945216
author Tanaka, Takumi S.
Akins, Hollis B.
Harikane, Yuichi
Silverman, John D.
Casey, Caitlin M.
Inayoshi, Kohei
Schindler, Jan-Torge
Shimasaku, Kazuhiro
Kocevski, Dale D.
Onoue, Masafusa
Faisst, Andreas L.
Robertson, Brant
Kokorev, Vasily
Shuntov, Marko
Koekemoer, Anton M.
Franco, Maximilien
Egami, Eiichi
Liu, Daizhong
Taylor, Anthony J.
Kartaltepe, Jeyhan S.
Bosman, Sarah E.
Champagne, Jaclyn B.
Kakiichi, Koki
Harish, Santosh
Zhang, Zijian
Newman, Sophie L.
Kakkad, Darshan
Fei, Qinyue
Fujimoto, Seiji
Li, Mingyu
Finkelstein, Steven L.
Li, Zi Jian
Lambrides, Erini
Sommovigo, Laura
Zavala, Jorge A.
Ito, Kei
Liu, Zhaoxuan
Treister, Ezequiel
Aravena, Manuel
Gozaliasl, Ghassem
Zhang, Haowen
Hatamnia, Hossein
Umeda, Hiroya
Inoue, Akio K.
Yang, Jinyi
Ando, Makoto
Arita, Junya
Ding, Xuheng
Matsui, Suin
Shibanuma, Yuki
Magdis, Georgios
Zhuang, Ming-Yang
Fan, Xiaohui
Li, Zihao
Liu, Weizhe
Lyu, Jianwei
Rhodes, Jason
Toft, Sune
Wang, Feige
Zou, Siwei
Arango-Toro, Rafael C.
Battisti, A. J.
Gillman, Steven
Khostovan, Ali Ahmad
Long, Arianna S.
Mobasher, Bahram
Sanders, David B.
author_facet Tanaka, Takumi S.
Akins, Hollis B.
Harikane, Yuichi
Silverman, John D.
Casey, Caitlin M.
Inayoshi, Kohei
Schindler, Jan-Torge
Shimasaku, Kazuhiro
Kocevski, Dale D.
Onoue, Masafusa
Faisst, Andreas L.
Robertson, Brant
Kokorev, Vasily
Shuntov, Marko
Koekemoer, Anton M.
Franco, Maximilien
Egami, Eiichi
Liu, Daizhong
Taylor, Anthony J.
Kartaltepe, Jeyhan S.
Bosman, Sarah E.
Champagne, Jaclyn B.
Kakiichi, Koki
Harish, Santosh
Zhang, Zijian
Newman, Sophie L.
Kakkad, Darshan
Fei, Qinyue
Fujimoto, Seiji
Li, Mingyu
Finkelstein, Steven L.
Li, Zi Jian
Lambrides, Erini
Sommovigo, Laura
Zavala, Jorge A.
Ito, Kei
Liu, Zhaoxuan
Treister, Ezequiel
Aravena, Manuel
Gozaliasl, Ghassem
Zhang, Haowen
Hatamnia, Hossein
Umeda, Hiroya
Inoue, Akio K.
Yang, Jinyi
Ando, Makoto
Arita, Junya
Ding, Xuheng
Matsui, Suin
Shibanuma, Yuki
Magdis, Georgios
Zhuang, Ming-Yang
Fan, Xiaohui
Li, Zihao
Liu, Weizhe
Lyu, Jianwei
Rhodes, Jason
Toft, Sune
Wang, Feige
Zou, Siwei
Arango-Toro, Rafael C.
Battisti, A. J.
Gillman, Steven
Khostovan, Ali Ahmad
Long, Arianna S.
Mobasher, Bahram
Sanders, David B.
contents JWST has revealed a new high-redshift population called little red dots (LRDs). Since LRDs may be in the early phase of black hole growth, identifying them in the early universe is crucial for understanding the formation of the first supermassive black holes. However, no robust LRD candidates have been identified at $z>10$, because commonly-used NIRCam photometry covers wavelengths up to $\sim5\,{\rm μm}$ and is insufficient to capture the characteristic V-shaped spectral energy distributions (SEDs) of LRDs. In this study, we present the first search for $z\gtrsim10$ LRD candidates using both NIRCam and MIRI imaging from COSMOS-Web, which provides the largest joint NIRCam-MIRI coverage to date ($0.20\,{\rm deg^2}$). Taking advantage of MIRI/F770W to remove contaminants, we identify one robust candidate, CW-LRD-z10 at $z_{\rm phot}=10.5^{+0.7}_{-0.6}$ with $M_{\rm UV}=-19.9^{+0.1}_{-0.2}\,{\rm mag}$. CW-LRD-z10 exhibits a compact morphology, a distinct V-shaped SED, and a non-detection in F115W, all consistent with being an LRD at $z\sim10$. Based on this discovery, we place the first constraint on the number density of LRDs at $z\sim10$ with $M_{\rm UV}\sim-20$ of $1.2^{+2.7}_{-1.0}\times10^{-6}\,{\rm Mpc^{-3}\,mag^{-1}}$, suggesting that the fraction of LRDs among the overall galaxy population increases with redshift, reaching $\sim3\%$ at $z\sim10$. Although deep spectroscopy is necessary to confirm the redshift and the nature of CW-LRD-z10, our results imply that LRDs may be a common population at $z>10$, playing a key role in the first supermassive black hole formation.
format Preprint
id arxiv_https___arxiv_org_abs_2508_00057
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Discovery of a Little Red Dot candidate at $z\gtrsim10$ in COSMOS-Web based on MIRI-NIRCam selection
Tanaka, Takumi S.
Akins, Hollis B.
Harikane, Yuichi
Silverman, John D.
Casey, Caitlin M.
Inayoshi, Kohei
Schindler, Jan-Torge
Shimasaku, Kazuhiro
Kocevski, Dale D.
Onoue, Masafusa
Faisst, Andreas L.
Robertson, Brant
Kokorev, Vasily
Shuntov, Marko
Koekemoer, Anton M.
Franco, Maximilien
Egami, Eiichi
Liu, Daizhong
Taylor, Anthony J.
Kartaltepe, Jeyhan S.
Bosman, Sarah E.
Champagne, Jaclyn B.
Kakiichi, Koki
Harish, Santosh
Zhang, Zijian
Newman, Sophie L.
Kakkad, Darshan
Fei, Qinyue
Fujimoto, Seiji
Li, Mingyu
Finkelstein, Steven L.
Li, Zi Jian
Lambrides, Erini
Sommovigo, Laura
Zavala, Jorge A.
Ito, Kei
Liu, Zhaoxuan
Treister, Ezequiel
Aravena, Manuel
Gozaliasl, Ghassem
Zhang, Haowen
Hatamnia, Hossein
Umeda, Hiroya
Inoue, Akio K.
Yang, Jinyi
Ando, Makoto
Arita, Junya
Ding, Xuheng
Matsui, Suin
Shibanuma, Yuki
Magdis, Georgios
Zhuang, Ming-Yang
Fan, Xiaohui
Li, Zihao
Liu, Weizhe
Lyu, Jianwei
Rhodes, Jason
Toft, Sune
Wang, Feige
Zou, Siwei
Arango-Toro, Rafael C.
Battisti, A. J.
Gillman, Steven
Khostovan, Ali Ahmad
Long, Arianna S.
Mobasher, Bahram
Sanders, David B.
Astrophysics of Galaxies
JWST has revealed a new high-redshift population called little red dots (LRDs). Since LRDs may be in the early phase of black hole growth, identifying them in the early universe is crucial for understanding the formation of the first supermassive black holes. However, no robust LRD candidates have been identified at $z>10$, because commonly-used NIRCam photometry covers wavelengths up to $\sim5\,{\rm μm}$ and is insufficient to capture the characteristic V-shaped spectral energy distributions (SEDs) of LRDs. In this study, we present the first search for $z\gtrsim10$ LRD candidates using both NIRCam and MIRI imaging from COSMOS-Web, which provides the largest joint NIRCam-MIRI coverage to date ($0.20\,{\rm deg^2}$). Taking advantage of MIRI/F770W to remove contaminants, we identify one robust candidate, CW-LRD-z10 at $z_{\rm phot}=10.5^{+0.7}_{-0.6}$ with $M_{\rm UV}=-19.9^{+0.1}_{-0.2}\,{\rm mag}$. CW-LRD-z10 exhibits a compact morphology, a distinct V-shaped SED, and a non-detection in F115W, all consistent with being an LRD at $z\sim10$. Based on this discovery, we place the first constraint on the number density of LRDs at $z\sim10$ with $M_{\rm UV}\sim-20$ of $1.2^{+2.7}_{-1.0}\times10^{-6}\,{\rm Mpc^{-3}\,mag^{-1}}$, suggesting that the fraction of LRDs among the overall galaxy population increases with redshift, reaching $\sim3\%$ at $z\sim10$. Although deep spectroscopy is necessary to confirm the redshift and the nature of CW-LRD-z10, our results imply that LRDs may be a common population at $z>10$, playing a key role in the first supermassive black hole formation.
title Discovery of a Little Red Dot candidate at $z\gtrsim10$ in COSMOS-Web based on MIRI-NIRCam selection
topic Astrophysics of Galaxies
url https://arxiv.org/abs/2508.00057