At a fixed halo mass , galaxy clusters with higher magnitude gaps have larger brightest central galaxy ( BCG ) stellar masses .
Recent studies have shown that by including the magnitude gap ( m _ { gap } ) as a latent parameter in the stellar mass - halo mass ( SMHM ) relation , we can make more precise measurements on the amplitude , slope , and intrinsic scatter .
Using galaxy clusters from the Sloan Digital Sky Survey , we measure the SMHM- m _ { gap } relation and its evolution out to z = 0.3 .
Using a fixed comoving aperture of 100kpc to define the central galaxy ’ s stellar mass , we report statistically significant negative evolution in the slope of the SMHM relation to z = 0.3 ( > 3.5 \sigma ) .
The steepening of the slope over the last 3.5 Gyrs can be explained by late-time merger activity at the cores of galaxy clusters .
We also find that the inferred slope depends on the aperture used to define the radial extent of the central galaxy .
At small radii ( 20kpc ) , the slope of the SMHM relation is shallow , indicating that the core of the central galaxy is less related to the growth of the underlying host halo .
By including all of the central galaxy ’ s light within 100kpc , the slope reaches an asymptote at a value consistent with recent high resolution hydrodynamical cosmology simulations .