The distribution of faint satellites around central galaxies in the CFHT Legacy Survey

TL;DR

This study analyzes the distribution and abundance of faint satellite galaxies around central galaxies using CFHT and SDSS data, revealing consistent power-law profiles and complex luminosity-dependent clustering trends.

Contribution

It provides new measurements of satellite distributions and luminosity functions, highlighting non-monotonic clustering behavior and differences from the Milky Way and M31.

Findings

Satellite distribution follows a power law with slope -1.05.

Clustering amplitude varies non-monotonically with satellite luminosity.

Milky Way/M31 has about twice as many satellites as typical central galaxies.

Abstract

We investigate the radial number density profile and the abundance distribution of faint satellites around central galaxies in the low redshift universe using the CFHT Legacy Survey. We consider three samples of central galaxies with magnitudes of M_r=-21, -22, and -23 selected from the Sloan Digital Sky Survey (SDSS) group catalog of Yang et al.. The satellite distribution around these central galaxies is obtained by cross-correlating these galaxies with the photometric catalogue of the CFHT Legacy Survey. The projected radial number density of the satellites obeys a power law form with the best-fit logarithmic slope of -1.05, independent of both the central galaxy luminosity and the satellite luminosity. The projected cross correlation function between central and satellite galaxies exhibits a non-monotonic trend with satellite luminosity. It is most pronounced for central galaxies with M_r=-21, where the decreasing trend of clustering amplitude with satellite luminosity is reversed when satellites are fainter than central galaxies by more than 2 magnitudes. A comparison with the satellite luminosity functions in the Milky Way and M31 shows that the Milky Way/M31 system has about twice as many satellites as around a typical central galaxy of similar luminosity. The implications for theoretical models are briefly discussed.