Abstract

Contributed Talk - Splinter GalaxyClusters

Tuesday, 08 September 2026, 17:05   (MW-1050)

Emission line galaxy model with a semi-analytic galaxy formation model, New Numerical Galaxy Catalog (ν2GC)

Kazuyuki Ogura, Masahiro Nagashima, Rhythm Shimakawa, Masakazu A. R. Kobayashi, Taira Oogi, Tomoaki Ishiyama, Yusei Koyama, Katsuya Okoshi, and Masato Onodera
Kobe City College of Technology, Bunkyo U., Waseda U., NAOJ, National Institute of Technology (NIT) Kure college, NIT Asahikawa college, Chiba U., Tokyo U. of Science

To investigate the evolution of the galaxies and structure formation, emission-line galaxies (ELGs) have been often used because emission lines from galaxies, such as [O II] (λλ3727, 3730), [O III] (λλ4959, 5007), and Hα (λ6563), are good indicators for the star formation rate (SFR) of galaxies. A strong point to focus on ELGs is that we can observe them over a significantly wide area by utilizing the combination of narrow-band (NB) filters and wide field cameras. On the other hand, the field variance (or “cosmic variance”) has been recognized as a serious problem in observational studies of high-z galaxies. It is the uncertainty of measuring the number density of galaxies, due to the underlying density fluctuation of dark matter. Indeed, while luminosity functions (LFs) of ELGs obtained by some different surveys generally show good agreement, some of them are in some disagreement by a factor of a few. To tackle this issue, we are working on constructing the models of ELGs by utilizing a semi-analytic galaxy formation mode, the New Numerical Galaxy Catalog (ν2GC). The ν2GC is successful to reproduce various statistical properties of galaxies at 0 < z < 6 by combining the state-of-the-art N-body simulation and phenomenological model. A remarkable aspect of the nu2GC is a large comoving volume up to ~25.7 Gpc^3 with sufficient mass resolution, which enables us to examine various properties of galaxies obtained by wide field surveys such as the Subaru Strategic Program survey with Hyper Suprime-Cam (HSC-SSP) and that with Prime-Focus Spectrograph (PFS-SSP). As a pilot study, we construct a model of Hα emitters (HAEs) with the ν2GC, resulting that it well reproduces the Hα luminosity function (LF) at z = 0.4 obtained by HSC-SSP observations (Ogura et al. 2020b). Based on the model, we have found that (1) HAEs are good tracer for the structure such as cosmic filaments, (2) the Hα LF within ~2 deg2 area show significant field variance up to ~1dex, and (3) >15 deg2 surveys are required to converge the luminosity function. In this presentation, we report the current status of our work on constructing the semi-analytic ELG models based on the ν2GC.