KiDS+GAMA: The weak lensing calibrated stellar-to-halo mass relation of central and satellite galaxies

TL;DR

This study uses weak lensing data from KiDS and GAMA to compare the halo masses of central and satellite galaxies, revealing satellites have smaller halos, consistent with galaxy formation models.

Contribution

It provides the first simultaneous weak lensing constraints on the stellar-to-halo mass relation for both central and satellite galaxies using combined KiDS and GAMA data.

Findings

Satellite galaxies have halo masses about 0.53 dex smaller than centrals of the same stellar mass.

Stacked tangential shear measurements are most effective for galaxy-halo studies.

Two-dimensional shear analysis does not improve precision over azimuthal averaging.

Abstract

We simultaneously present constraints on the stellar-to-halo mass relation for central and satellite galaxies through a weak lensing analysis of spectroscopically classified galaxies. Using overlapping data from the fourth data release of the Kilo-Degree Survey (KiDS), and the Galaxy And Mass Assembly survey (GAMA), we find that satellite galaxies are hosted by halo masses that are $0.53 \pm 0.39$ dex (68\% confidence, $3\sigma$ detection) smaller than those of central galaxies of the same stellar mass (for a stellar mass of $\log(M_{\star}/M_{\odot}) = 10.6$). This is consistent with galaxy formation models, whereby infalling satellite galaxies are preferentially stripped of their dark matter. We find consistent results with similar uncertainties when comparing constraints from a standard azimuthally averaged galaxy-galaxy lensing analysis and a two-dimensional likelihood analysis of the full shear field. As the latter approach is somewhat biased due to the lens incompleteness and as it does not provide any improvement to the precision when applied to actual data, we conclude that stacked tangential shear measurements are best-suited for studies of the galaxy-halo connection.