Quantifying the effect of field variance on the H\(\alpha\) luminosity function with the New Numerical Galaxy Catalogue (\(\nu^2\)GC)

• Published in: arXiv.org 2020-04
• Main Authors: Ogura, Kazuyuki, Nagashima, Masahiro, Shimakawa, Rhythm, Hayashi, Masao, Kobayashi, Masakazu A R, Taira Oogi, Ishiyama, Tomoaki, Koyama, Yusei, Ryu Makiya, Okoshi, Katsuya, Onodera, Masato, Shirakata, Hikari
• Format: Article
• Language: English
• Subjects: Emitters; Galactic evolution; Large scale structure of the universe; Luminosity; Mathematical models; Spatial distribution; Star & galaxy formation; Star formation
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.2004.00815

We construct a model of H\(\alpha\) emitters (HAEs) based on a semi-analytic galaxy formation model, the New Numerical Galaxy Catalog (\(\nu^2\)GC). In this paper, we report our estimate for the field variance of the HAE distribution. By calculating the H\(\alpha\) luminosity from the star-formation rate of galaxies, our model well reproduces the observed H\(\alpha\) luminosity function (LF) at \(z=0.4\). The large volume of the \(\nu^2\)GC makes it possible to examine the spatial distribution of HAEs over a region of (411.8 Mpc)\(^3\) in the comoving scale. The surface number density of \(z=0.4\) HAEs with \(L_{\rm H\alpha} \geq 10^{40}\) erg s\(^{-1}\) is 308.9 deg\(^{-2}\). We have confirmed that the HAE is a useful tracer for the large-scale structure of the Universe because of their significant overdensity (\(>\) 5\(\sigma\)) at clusters and the filamentary structures. The H\(\alpha\) LFs within a survey area of \(\sim\)2 deg\(^2\) (typical for previous observational studies) show a significant field variance up to \(\sim\)1 dex. Based on our model, one can estimate the variance on the H\(\alpha\) LFs within given survey areas.