Angular clustering of z~2 star-forming and passive galaxies in 2.5 square degrees of deep CFHT imaging

TL;DR

This study analyzes the angular clustering of star-forming and passive galaxies at z~2 over 2.5 square degrees, revealing how galaxy properties relate to their environments and halo masses, with implications for galaxy evolution.

Contribution

It provides a detailed analysis of galaxy clustering at z~2, highlighting differences between galaxy types and the importance of large-area surveys for understanding galaxy evolution.

Findings

Passive galaxies reside in more massive halos.

Clustering strength varies with luminosity and galaxy type.

Environmental effects influence galaxy quenching at z~2.

Abstract

We study the angular clustering of z~2 galaxies using ~40,000 star-forming (SF) and ~5,000 passively-evolving (PE) galaxies selected from ~2.5 deg$^2$ of deep ($K_{lim}$=23-24 AB) CFHT imaging. For both populations the clustering is stronger for galaxies brighter in rest-frame optical and the trend is particularly strong for PE galaxies, indicating that passive galaxies with larger stellar masses reside in more massive halos. In contrast, at rest-frame UV we find that while the clustering of SF galaxies increases with increasing luminosity, it decreases for PE galaxies; a possible explanation lies in quenching of star formation in the most massive halos. Furthermore, we find two components in the correlation functions for both SF and PE galaxies, attributable to one- and two-halo terms. The presence of one-halo terms for both PE and SF galaxies suggests that environmental effects were producing passive galaxies in virtualized environments already by z~2. Finally, we find notable clustering differences between the four widely-separated fields in our study; the popular COSMOS field is the most discrepant (as is also the case for number counts and luminosity functions), highlighting the need for very large areas and multiple sightlines in galaxy evolution statistical studies.