Clustering properties of high redshift red galaxies in SA22 from the UKIDSS DXS

TL;DR

This study measures the clustering of high-redshift red galaxies in a large survey area, revealing complex clustering behaviors and differences among galaxy types, providing the most representative large-scale clustering data for massive galaxies at z>1.

Contribution

It presents the first large-area, deep near-infrared survey analysis of galaxy clustering at high redshift, including detailed clustering properties of EROs and DRGs, and investigates cosmic variance effects.

Findings

Both EROs and DRGs are strongly clustered with double power-law correlation functions.

Clustering strength varies with galaxy brightness and color, indicating different galaxy populations.

Cosmic variance impacts clustering measurements, emphasizing the importance of large-area surveys.

Abstract

Deep, wide, near-infrared imaging surveys provide an opportunity to study the clustering of various galaxy populations at high redshift on the largest physical scales. We have selected $1<z<2$ extremely red objects (EROs) and $1<z<3$ distant red galaxies (DRGs) in SA22 from the near-infrared photometric data of the UKIDSS Deep eXtragalactic Survey (DXS) and $gri$ optical data from CTIO covering 3.3~deg$^2$. This is the largest contiguous area studied to sufficient depth to select these distant galaxies to date. The angular two-point correlation functions and the real space correlation lengths of each population are measured and show that both populations are strongly clustered and that the clustering cannot be parameterised with a single power law. The correlation function of EROs shows a double power law with the inflection at $\sim$ 0.6$'$--1.2$'$ (0.6--1.2~h$^{-1}$~Mpc). The bright EROs ($K<18.8$) show stronger clustering on small scales but similar clustering on larger scales, whereas redder EROs show stronger clustering on all scales. Clustering differences between EROs that are old passively evolved galaxies (OGs) and dusty star-forming galaxies (DGs), on the basis of their $J-K$ colour, are also investigated. The clustering of $r-K$ EROs are compared with that of $i-K$ EROs and the differences are consistent with their expected redshift distributions. The correlation function of DRGs is also well described by a double power law and consistent with previous studies once the effects of the broader redshift distribution our selection of DRGs returns are taken into account. We also perform the same analysis on smaller sub-fields to investigate the impact of cosmic variance on the derived clustering properties. Currently this study is the most representative measurement of the clustering of massive galaxies at $z>1$ on large scales.