The SLUGGS Survey: The globular cluster systems of three early-type
  galaxies using wide-field imaging
  We present the results from a wide-field imaging study of globular cluster
(GC) systems in three early-type galaxies. Combinations of Subaru/Suprime-Cam,
CFHT/MegaCam and HST/WFPC2/ACS data were used to determine the GC system
properties of three highly flattened galaxies NGC 720, NGC 1023 and NGC 2768.
This work is the first investigation of the GC system in NGC 720 and NGC 2768
to very large galactocentric radius ($\sim$ 100 kpc). The three galaxies have
clear blue and red GC subpopulations. The radial surface densities of the GC
systems are fitted with Sersic profiles, and detected out to 15, 8 and 10
galaxy effective radii respectively. The total number of GCs and specific
frequency are determined for each GC system. The ellipticity of the red
subpopulation is in better agreement with the host galaxy properties than is
the blue subpopulation, supporting the traditional view that metal-rich GCs are
closely associated with the bulk of their host galaxies' field stars, while
metal-poor GCs reflect a distinct stellar halo. With the addition of another 37
literature studied galaxies, we present a new correlation of GC system extent
with host galaxy effective radius. We find a dependence of the relative
fraction of blue to red GCs with host galaxy environmental density for
lenticular galaxies (but not for elliptical or spiral galaxies). We propose
that tidal interactions between galaxies in cluster environments might be the
reason behind the observed trend for lenticular galaxies.
