Satellite Kinematics III: Halo Masses of Central Galaxies in SDSS

TL;DR

This study uses satellite galaxy kinematics from SDSS to refine the understanding of how central galaxy properties relate to their dark matter halo masses, highlighting the importance of stellar mass over luminosity.

Contribution

It provides new insights into the halo mass-stellar mass and halo mass-luminosity relations, emphasizing the role of galaxy color and stellar mass in these scaling relations.

Findings

Red centrals occupy more massive haloes than blue at fixed luminosity.

No significant halo mass difference between red and blue centrals at fixed stellar mass for M* ≤ 10^{10.5} h^{-2} Msun.

The scatter in halo mass at fixed stellar mass varies with galaxy color and stellar mass.

Abstract

We use the kinematics of satellite galaxies that orbit around the central galaxy in a dark matter halo to infer the scaling relations between halo mass and central galaxy properties. Using galaxies from the Sloan Digital Sky Survey, we investigate the halo mass-luminosity relation (MLR) and the halo mass-stellar mass relation (MSR) of central galaxies. In particular, we focus on the dependence of these scaling relations on the colour of the central galaxy. We find that red central galaxies on average occupy more massive haloes than blue central galaxies of the same luminosity. However, at fixed stellar mass there is no appreciable difference in the average halo mass of red and blue centrals, especially for M* $\lsim$ 10^{10.5} h^{-2} Msun. This indicates that stellar mass is a better indicator of halo mass than luminosity. Nevertheless, we find that the scatter in halo masses at fixed stellar mass is non-negligible for both red and blue centrals. It increases as a function of stellar mass for red centrals but shows a fairly constant behaviour for blue centrals. We compare the scaling relations obtained in this paper with results from other independent studies of satellite kinematics, with results from a SDSS galaxy group catalog, from galaxy-galaxy weak lensing measurements, and from subhalo abundance matching studies. Overall, these different techniques yield MLRs and MSRs in fairly good agreement with each other (typically within a factor of two), indicating that we are converging on an accurate and reliable description of the galaxy-dark matter connection. We briefly discuss some of the remaining discrepancies among the various methods.