Galaxy properties from the outskirts to the core of a protocluster at z = 3.70

Jun Toshikawa; Stijn Wuyts; Nobunari Kashikawa; Hisakazu Uchiyama; Malcolm Bremer; Marcin Sawicki; Yoshiaki Ono; Mariko Kubo; Kei Ito; Sadman S. Ali

doi:10.1093/mnras/staf197

Galaxy properties from the outskirts to the core of a protocluster at z = 3.70

Jun Toshikawa, Stijn Wuyts, Nobunari Kashikawa, Hisakazu Uchiyama, Malcolm Bremer, Marcin Sawicki, Yoshiaki Ono, Mariko Kubo, Kei Ito, Sadman S. Ali

Research output: Contribution to journal › Article › peer-review

Abstract

We study the dependence of galaxy properties on their spatial position within a protocluster by carrying out follow-up spectroscopy on a protocluster candidate selected from the wide-field imaging of the Hyper SuprimeCam Subaru Strategic Programme. In the 4.5σ surface-overdense region of g-dropout galaxies, we now spectroscopically confirm that 13 galaxies, at least, are clustering in a narrow redshift range of ∆ z < 0.05 around z=3.70. Next, we investigate the physical properties and three-dimensional (3D) distribution of the protocluster’s member galaxies. Based on spectroscopically confirmed g-dropout galaxies, we find an overabundance of rest-frame ultraviolet (UV) bright galaxies in the protocluster. The UV brightest protocluster member turns out to be an active galactic nucleus, and the other UV brighter members tend to show smaller Lyα equivalent widths than field counterparts. The member galaxies tend to densely populate near the 3D centre of the protocluster, but the separation from the nearest neighbour rather than the distance from the centre of the protocluster is more tightly correlated to galaxy properties, implying that the protocluster is still in an early phase of cluster formation and only close neighbours have a significant impact on the physical properties of protocluster members. The number density of massive galaxies, selected from an archival photometric-redshift catalogue, is higher near the centre of the protocluster, while dusty starburst galaxies are distributed on the outskirts. The protocluster thus appears to consist of multiple galaxy populations, whose spatial distributions reveal the developmental stage of the galaxy cluster.

Original language	English
Pages (from-to)	3561-3574
Number of pages	14
Journal	Monthly Notices of the Royal Astronomical Society
Volume	537
Issue number	4
Early online date	5 Feb 2025
DOIs	https://doi.org/10.1093/mnras/staf197
Publication status	Published - 31 Mar 2025

Data Availability Statement

The data underlying this article will be shared on reasonable request to the corresponding author.

Acknowledgements

We thank Tom Bakx for valuable comments and suggestions that significantly improved the manuscript.
This paper makes use of software developed for the Large Synoptic Survey Telescope (LSST). We thank the LSST Project for making their code available as free software at http://dm.lsst.org. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the Native Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain.

Funding

JT and SW acknowledge support from Science and Technology Facilities Council (STFC) through grant ST/T000449/1, and JT acknowledges support from the research grant programme of Kawanishi Memorial ShinMaywa Education Foundation. Some of the data presented herein were obtained at Keck Observatory, which is a private 501(c)3 non-profit organization operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The HSC collaboration includes the astronomical communities of Japan and Taiwan, and Princeton University. The HSC instrumentation and software were developed by the National Astronomical Observatory of Japan (NAOJ), the Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU), the University of Tokyo, the High Energy Accelerator Research Organization (KEK), the Academia Sinica Institute for Astronomy and Astrophysics in Taiwan (ASIAA), and Princeton University. Funding was contributed by the FIRST programe from Japanese Cabinet Office, the Ministry of Education, Culture, Sports, Science and Technology (MEXT), the Japan Society for the Promotion of Science (JSPS), Japan Science and Technology Agency (JST), the Toray Science Foundation, NAOJ, Kavli IPMU, KEK, ASIAA, and Princeton University.

Keywords

galaxies: evolution
galaxies: high-redshift

ASJC Scopus subject areas

Astronomy and Astrophysics
Space and Planetary Science

Access to Document

10.1093/mnras/staf197Licence: CC BY

Cite this

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abstract = "We study the dependence of galaxy properties on their spatial position within a protocluster by carrying out follow-up spectroscopy on a protocluster candidate selected from the wide-field imaging of the Hyper SuprimeCam Subaru Strategic Programme. In the 4.5σ surface-overdense region of g-dropout galaxies, we now spectroscopically confirm that 13 galaxies, at least, are clustering in a narrow redshift range of ∆ z < 0.05 around z=3.70. Next, we investigate the physical properties and three-dimensional (3D) distribution of the protocluster{\textquoteright}s member galaxies. Based on spectroscopically confirmed g-dropout galaxies, we find an overabundance of rest-frame ultraviolet (UV) bright galaxies in the protocluster. The UV brightest protocluster member turns out to be an active galactic nucleus, and the other UV brighter members tend to show smaller Lyα equivalent widths than field counterparts. The member galaxies tend to densely populate near the 3D centre of the protocluster, but the separation from the nearest neighbour rather than the distance from the centre of the protocluster is more tightly correlated to galaxy properties, implying that the protocluster is still in an early phase of cluster formation and only close neighbours have a significant impact on the physical properties of protocluster members. The number density of massive galaxies, selected from an archival photometric-redshift catalogue, is higher near the centre of the protocluster, while dusty starburst galaxies are distributed on the outskirts. The protocluster thus appears to consist of multiple galaxy populations, whose spatial distributions reveal the developmental stage of the galaxy cluster.",

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AU - Kashikawa, Nobunari

AU - Uchiyama, Hisakazu

AU - Bremer, Malcolm

AU - Sawicki, Marcin

AU - Ono, Yoshiaki

AU - Kubo, Mariko

AU - Ito, Kei

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Galaxy properties from the outskirts to the core of a protocluster at z = 3.70

Abstract

Data Availability Statement

Acknowledgements

Funding

Keywords

ASJC Scopus subject areas

Access to Document

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Astrophysics at the University of Bath 2020-2023

Cite this

Galaxy properties from the outskirts to the core of a protocluster at z = 3.70

Abstract

Data Availability Statement

Acknowledgements

Funding

Keywords

ASJC Scopus subject areas

Access to Document

Other files and links

Fingerprint

Projects

Astrophysics at the University of Bath 2020-2023

Cite this