PEGASUS (Pfs Emission-line GAlaxy SUrvey with Subaru): I. Three-dimensional large-scale structures at z > 1 probed with emission-line galaxies

@misc{kubo2026pegasus,
  title = {{PEGASUS (Pfs Emission-line GAlaxy SUrvey with Subaru): I. Three-dimensional large-scale structures at $z > 1$ probed with emission-line galaxies}},
  author = {Mariko Kubo and Tadayuki Kodama and Rhythm Shimakawa and Yusei Koyama and Masato Onodera and Akio K. Inoue and Hisakazu Uchiyama and Tohru Nagao and Ken-ichi Tadaki and Ronaldo Laishram and Ryoma Wagatsuma and Chen Nuo and Haruka Kusakabe and Satoshi Kikuta and Yuma Sugahara and Kentaro Motohara and Kazuki Daikuhara and Ken Osato and Yongming Liang},
  howpublished = {arXiv},
  year = {2026},
  month = sep,
  doi = {10.48550/arxiv.2609.25455},
  eprint = {2609.25455},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2609.25455},
  note = {CC BY 4.0},
}

TY  - UNPB
TI  - PEGASUS (Pfs Emission-line GAlaxy SUrvey with Subaru): I. Three-dimensional large-scale structures at z > 1 probed with emission-line galaxies
AU  - Mariko Kubo
AU  - Tadayuki Kodama
AU  - Rhythm Shimakawa
AU  - Yusei Koyama
AU  - Masato Onodera
AU  - Akio K. Inoue
AU  - Hisakazu Uchiyama
AU  - Tohru Nagao
AU  - Ken-ichi Tadaki
AU  - Ronaldo Laishram
AU  - Ryoma Wagatsuma
AU  - Chen Nuo
AU  - Haruka Kusakabe
AU  - Satoshi Kikuta
AU  - Yuma Sugahara
AU  - Kentaro Motohara
AU  - Kazuki Daikuhara
AU  - Ken Osato
AU  - Yongming Liang
PY  - 2026
DA  - 2026/09/21
PB  - arXiv
DO  - 10.48550/arxiv.2609.25455
UR  - https://arxiv.org/abs/2609.25455
AB  - To comprehensively understand the environmental effects on galaxy evolution, it is crucial to precisely map the distribution and thoroughly examine the properties of galaxies, including low-mass building blocks. Deep narrow-band imaging observations conducted with Hyper Suprime-Cam (HSC) on the Subaru Telescope systematically probed the distribution of low-mass star-forming galaxies as Hα, [O {\footnotesize II}], and [O {\footnotesize III}] emission-line galaxies at 0.4≤ z≤1.6. We perform a comprehensive spectroscopic follow-up observation of these emission-line galaxies with narrow-band-based emission-line fluxes ≥ 2×10^−17 erg s^−1 cm^−2 within ≈1.8 deg^2 area centered on the COSMOS field using `Ōnohi`ula - Prime Focus Spectrograph (PFS) on the Subaru Telescope. In this paper, we outline the data product and present the large-scale structures at z>1. 9079 out of 9917 of the targets are observed, and the redshifts of 92\%~of the observed targets are successfully confirmed. We survey groups, filamentary large-scale structures, and voids at z=1.19, $1.47$, and $1.60$ based on the three-dimensional distribution of 520−920 [O {\footnotesize II}] emission-line galaxies with stellar masses M_⋆≥10^9.5 M_⊙ at each redshift. Groups with halo masses 1×10^12−6×10^13 M_⊙ are identified along the filaments, whereas the most massive groups are located at the densest intersections of filaments as predicted by cosmological simulations. Voids hidden on the surface density maps are robustly extracted on the volume density map. Our spectroscopic sample provides a powerful basis for quantifying the evolution of galaxies along the diverse environments back in time toward cosmic noon epoch in forthcoming papers.
ER  -