Clustering properties and halo masses for central galaxies in the local Universe

TL;DR

This study analyzes how clustering and dark matter halo mass of central galaxies depend primarily on stellar mass, with minimal influence from other properties, highlighting the importance of separating central and satellite galaxies in such analyses.

Contribution

It demonstrates that stellar mass is the most indicative property of halo mass for central galaxies, supporting previous assumptions and emphasizing the need to distinguish between central and satellite galaxies.

Findings

Clustering and halo mass depend mainly on stellar mass for centrals.

Satellite and full galaxy populations show similar clustering at high masses.

At low masses, clustering correlates with velocity dispersion and color.

Abstract

We investigate the clustering and dark matter halo mass for a sample of $\sim$16,000 central galaxies selected from the SDSS/DR7 group catalog. We select subsamples of central galaxies on three two-dimensional planes, each formed by stellar mass ($M_{\star}$) and one of the other properties including optical color (g-r) , surface stellar mass density ($\mu_{\star}$) and central stellar velocity dispersion ($\sigma_{\star}$). For each subsample we measure both the projected cross-correlation function ($w_{p}(r_{p})$) relative to a reference galaxy sample, and an average mass of the host dark matter halos ($M_{halo}$) . For comparison we have also estimated the $w_{p}(r_{p})$ for the full galaxy population and the subset of satellite galaxies. We find that, for central galaxies, both $w_{p}(r_{p})$ and $M_{halo}$ show strongest dependence on $M_{\star}$, and there is no clear dependence on other properties when stellar mass is fixed. This result provides strong support to the previously-adopted assumption that, for central galaxies, stellar mass is the galaxy property that is best indicative of the host dark halo mass. The full galaxy population and the subset of satellites show similar clustering properties in all cases. However, they are similar to the centrals only at high masses ($M_{\star} \geq 10^{11} M_{\odot}$). At low-mass ($M_{\star} \leq 10^{11} M_{\odot}$), the results are different: the $w_{p}(r_{p})$ increases with both $\sigma$ and g-r when $M_{\star}$ is fixed, and depends very weakly on $M_{\star}$ when $\sigma_{\star}$ or g-r is fixed. At fixed $M_{star}$, the $\mu_{\star}$ shows weak correlations with clustering amplitude (and halo mass for central galaxies). Our results suggest that it is necessary to consider central and satellite galaxies separately when studying the link between galaxies and dark matter halos. (Abridged)