A Wide and Deep Exploration of Radio Galaxies with Subaru HSC (WERGS). X. The Massive and Passive Nature of Radio Galaxies at z ∼ 4

High- z radio galaxies (HzRGs) are considered important objects for understanding the formation and evolution of massive galaxies in the early Universe. However, until to date, detailed studies of the stellar population of HzRGs, such as the star formation history, have been scarce. Therefore, this...

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Main Authors: Yuta Yamamoto, Tohru Nagao, Takuji Yamashita, Hisakazu Uchiyama, Mariko Kubo, Yoshiki Toba, Yuichi Harikane, Kohei Ichikawa, Masaru Kajisawa, Akatoki Noboriguchi, Yoshiaki Ono, Toshihiro Kawaguchi
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Language:English
Published: IOP Publishing 2024-01-01
Series:The Astrophysical Journal
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Online Access:https://doi.org/10.3847/1538-4357/ad9562
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author Yuta Yamamoto
Tohru Nagao
Takuji Yamashita
Hisakazu Uchiyama
Mariko Kubo
Yoshiki Toba
Yuichi Harikane
Kohei Ichikawa
Masaru Kajisawa
Akatoki Noboriguchi
Yoshiaki Ono
Toshihiro Kawaguchi
author_facet Yuta Yamamoto
Tohru Nagao
Takuji Yamashita
Hisakazu Uchiyama
Mariko Kubo
Yoshiki Toba
Yuichi Harikane
Kohei Ichikawa
Masaru Kajisawa
Akatoki Noboriguchi
Yoshiaki Ono
Toshihiro Kawaguchi
author_sort Yuta Yamamoto
collection DOAJ
description High- z radio galaxies (HzRGs) are considered important objects for understanding the formation and evolution of massive galaxies in the early Universe. However, until to date, detailed studies of the stellar population of HzRGs, such as the star formation history, have been scarce. Therefore, this study conducted a new survey to establish a less-biased sample of HzRGs and consequently investigate their properties. We utilized a sample of g -dropout Lyman break galaxies (LBGs) obtained from an optical wide and deep imaging survey made by Subaru Hyper Suprime-Cam. Based on the cross matching of this LBG sample with the Very Large Array Faint Images of the Radio Sky at Twenty cm radio survey data, we constructed a photometric sample of HzRGs at z ∼ 4 for a ∼560 deg ^2 survey field. Consequently, we identified 146 HzRG candidates. To analyze the characteristics of these candidates, we focus on objects exhibiting the near-infrared photometry of VIKING or UKIRT Infrared Deep Sky Survey and the mid-infrared photometry of unWISE (28 objects). The results indicate that seven objects exhibit spectral energy distributions (SEDs) consistent with galaxies at z ∼ 4. The HzRG candidates have very large stellar masses with ∼4.2 × 10 ^11 M _⊙ on average. This stellar mass is similar to that of previously discovered ultra-steep-spectrum HzRGs at z ∼ 4, though our sample is affected by a sample selection bias that selects only HzRGs with M _⋆ > 10 ^11 M _⊙ . Further, the SEDs of those HzRG candidates suggest a past fast quenching with a rough timescale of ∼0.1 Gyr, as evidenced from the rest-frame UVJ diagram.
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spelling doaj-art-3d541f19c5bf4b9f95bb127b6ea44e902025-08-20T02:00:55ZengIOP PublishingThe Astrophysical Journal1538-43572024-01-01978110210.3847/1538-4357/ad9562A Wide and Deep Exploration of Radio Galaxies with Subaru HSC (WERGS). X. The Massive and Passive Nature of Radio Galaxies at z ∼ 4Yuta Yamamoto0https://orcid.org/0009-0008-3501-7773Tohru Nagao1Takuji Yamashita2https://orcid.org/0000-0002-4999-9965Hisakazu Uchiyama3https://orcid.org/0000-0002-0673-0632Mariko Kubo4Yoshiki Toba5https://orcid.org/0000-0002-3531-7863Yuichi Harikane6https://orcid.org/0000-0002-6047-430XKohei Ichikawa7Masaru Kajisawa8Akatoki Noboriguchi9Yoshiaki Ono10Toshihiro Kawaguchi11https://orcid.org/0000-0002-3866-9645Graduate School of Science and Engineering, Ehime University , 2-5 Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan ; yamamoto@cosmos.phys.sci.ehime-u.ac.jpResearch Center for Space and Cosmic Evolution, Ehime University , 2-5 Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan; Amanogawa Galaxy Astronomy Research Center, Kagoshima University , 1-21-35 Korimoto, Kagoshima 890-0065, JapanNational Astronomical Observatory of Japan , 2-21-1 Osawa, Mitaka, Tokyo 181-8588, JapanNational Astronomical Observatory of Japan , 2-21-1 Osawa, Mitaka, Tokyo 181-8588, JapanAstronomical Institute, Tohoku University , 6-3 Aramaki, Aoba-ku, Sendai, Miyagi 980-8578, JapanResearch Center for Space and Cosmic Evolution, Ehime University , 2-5 Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan; National Astronomical Observatory of Japan , 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan; Academia Sinica Institute of Astronomy and Astrophysics , 11F of Astronomy-Mathematics Building, AS/NTU, No.1, Section 4, Roosevelt Road, Taipei 10617, TaiwanInstitute for Cosmic Ray Research, The University of Tokyo , 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8582, JapanDepartment of Physics, School of Advanced Science and Engineering, Faculty of Science and Engineering, Waseda University , 3-4-1 Okubo, Shinjuku, Tokyo 169-8555, JapanGraduate School of Science and Engineering, Ehime University , 2-5 Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan ; yamamoto@cosmos.phys.sci.ehime-u.ac.jpSchool of General Education, Shinshu University , 3-1-1 Asahi, Matsumoto, Nagano 390-8621, JapanInstitute for Cosmic Ray Research, The University of Tokyo , 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8582, JapanDepartment of Economics, Management and Information Science, Onomichi City University , Hisayamada 1600-2, Onomichi, Hiroshima 722-8506, JapanHigh- z radio galaxies (HzRGs) are considered important objects for understanding the formation and evolution of massive galaxies in the early Universe. However, until to date, detailed studies of the stellar population of HzRGs, such as the star formation history, have been scarce. Therefore, this study conducted a new survey to establish a less-biased sample of HzRGs and consequently investigate their properties. We utilized a sample of g -dropout Lyman break galaxies (LBGs) obtained from an optical wide and deep imaging survey made by Subaru Hyper Suprime-Cam. Based on the cross matching of this LBG sample with the Very Large Array Faint Images of the Radio Sky at Twenty cm radio survey data, we constructed a photometric sample of HzRGs at z ∼ 4 for a ∼560 deg ^2 survey field. Consequently, we identified 146 HzRG candidates. To analyze the characteristics of these candidates, we focus on objects exhibiting the near-infrared photometry of VIKING or UKIRT Infrared Deep Sky Survey and the mid-infrared photometry of unWISE (28 objects). The results indicate that seven objects exhibit spectral energy distributions (SEDs) consistent with galaxies at z ∼ 4. The HzRG candidates have very large stellar masses with ∼4.2 × 10 ^11 M _⊙ on average. This stellar mass is similar to that of previously discovered ultra-steep-spectrum HzRGs at z ∼ 4, though our sample is affected by a sample selection bias that selects only HzRGs with M _⋆ > 10 ^11 M _⊙ . Further, the SEDs of those HzRG candidates suggest a past fast quenching with a rough timescale of ∼0.1 Gyr, as evidenced from the rest-frame UVJ diagram.https://doi.org/10.3847/1538-4357/ad9562Galaxy evolution
spellingShingle Yuta Yamamoto
Tohru Nagao
Takuji Yamashita
Hisakazu Uchiyama
Mariko Kubo
Yoshiki Toba
Yuichi Harikane
Kohei Ichikawa
Masaru Kajisawa
Akatoki Noboriguchi
Yoshiaki Ono
Toshihiro Kawaguchi
A Wide and Deep Exploration of Radio Galaxies with Subaru HSC (WERGS). X. The Massive and Passive Nature of Radio Galaxies at z ∼ 4
The Astrophysical Journal
Galaxy evolution
title A Wide and Deep Exploration of Radio Galaxies with Subaru HSC (WERGS). X. The Massive and Passive Nature of Radio Galaxies at z ∼ 4
title_full A Wide and Deep Exploration of Radio Galaxies with Subaru HSC (WERGS). X. The Massive and Passive Nature of Radio Galaxies at z ∼ 4
title_fullStr A Wide and Deep Exploration of Radio Galaxies with Subaru HSC (WERGS). X. The Massive and Passive Nature of Radio Galaxies at z ∼ 4
title_full_unstemmed A Wide and Deep Exploration of Radio Galaxies with Subaru HSC (WERGS). X. The Massive and Passive Nature of Radio Galaxies at z ∼ 4
title_short A Wide and Deep Exploration of Radio Galaxies with Subaru HSC (WERGS). X. The Massive and Passive Nature of Radio Galaxies at z ∼ 4
title_sort wide and deep exploration of radio galaxies with subaru hsc wergs x the massive and passive nature of radio galaxies at z ∼ 4
topic Galaxy evolution
url https://doi.org/10.3847/1538-4357/ad9562
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