We measure the half-light radii of globular clusters ( GCs ) in 43 galaxies from the ACS Fornax Cluster Survey ( ACSFCS ) .
We use these data to extend previous work in which the environmental dependencies of the half-light radii of GCs in early type galaxies in the ACS Virgo Cluster Survey ( ACSVCS ) were studied , and a corrected mean half-light radius ( corrected for the observed environmental trends ) was suggested as a reliable distance indicator .
This work both increases the sample size for the study of the environmental dependencies , and adds leverage to the study of the corrected half-light radius as a possible distance indicator ( since Fornax lies at a larger distance than the Virgo cluster ) .
We study the environmental dependencies of the size of GCs using both a Principal Component Analysis ( PCA ) as well as 2D scaling relations .
We largely confirm the environmental dependencies shown in Jordán et al .
( 23 ) , but find evidence that there is a residual correlation in the mean half-light radius of GC systems with galaxy magnitude , and subtle differences in the other correlations — so there may not be a universal correction for the half-light radii of lower luminosity galaxy GC systems .
The main factor determining the size of a GC in an early type galaxy is the GC color .
Red GCs have \langle r _ { h } \rangle = 2.8 \pm 0.3 Â pc , while blue GCs have \langle r _ { h } \rangle = 3.4 \pm 0.3 Â pc .
We show that for bright early-type galaxies ( M _ { B } < -19 mag ) , the uncorrected mean half-light radius of the GC system is by itself an excellent distance indicator ( with error \sim 11 % ) , having the potential to reach cosmologically interesting distances in the era of high angular resolution adaptive optics on large optical telescopes .