Abundance matching analysis of the emission line galaxy sample in the extended Baryon Oscillation Spectroscopic Survey

TL;DR

This study models the small-scale clustering of emission line galaxies in eBOSS using abundance matching, revealing insights into galaxy-halo connections, satellite fractions, and assembly bias effects.

Contribution

It introduces a conditional abundance matching method incorporating star formation rate and halo accretion rate to accurately reproduce eBOSS ELG clustering.

Findings

Reproduces small-scale clustering within 1σ error.

eBOSS ELGs are about 12% of all star-forming galaxies.

Satellite fraction of eBOSS ELGs is approximately 19.3%.

Abstract

We present the measurements of the small-scale clustering for the emission line galaxy (ELG) sample from the extended Baryon Oscillation Spectroscopic Survey (eBOSS) in the Sloan Digital Sky Survey IV (SDSS-IV). We use conditional abundance matching method to interpret the clustering measurements from $0.34h^{-1}\textrm{Mpc}$ to $70h^{-1}\textrm{Mpc}$. In order to account for the correlation between properties of emission line galaxies and their environment, we add a secondary connection between star formation rate of ELGs and halo accretion rate. Three parameters are introduced to model the ELG [OII] luminosity and to mimic the target selection of eBOSS ELGs. The parameters in our models are optimized using Markov Chain Monte Carlo (MCMC) method. We find that by conditionally matching star formation rate of galaxies and the halo accretion rate, we are able to reproduce the eBOSS ELG small scale clustering within 1$\sigma$ error level. Our best fit model shows that the eBOSS ELG sample only consists of $\sim 12\%$ of all star-forming galaxies, and the satellite fraction of eBOSS ELG sample is 19.3\%. We show that the effect of assembly bias is $\sim20\%$ on the two-point correlation function and $\sim5\%$ on the void probability function at scale of $r\sim 20 h^{-1}\rm Mpc$.