Isolated ellipticals and their globular cluster systems III. NGC 2271,
  NGC 2865, NGC 3962, NGC 4240 and IC 4889
  As tracers of star formation, galaxy assembly and mass distribution, globular
clusters have provided important clues to our understanding of early-type
galaxies. But their study has been mostly constrained to galaxy groups and
clusters where early-type galaxies dominate, leaving the properties of the
globular cluster systems (GCSs) of isolated ellipticals as a mostly uncharted
territory. We present Gemini-South/GMOS $g'i'$ observations of five isolated
elliptical galaxies: NGC 3962, NGC 2865, IC 4889, NGC 2271 and NGC 4240.
Photometry of their GCSs reveals clear color bimodality in three of them,
remaining inconclusive for the other two. All the studied GCSs are rather poor
with a mean specific frequency $S_N\sim 1.5$, independently of the parent
galaxy luminosity. Considering also previous work, it is clear that bimodality
and especially the presence of a significant, even dominant, population of blue
clusters occurs at even the most isolated systems, casting doubts on a possible
accreted origin of metal-poor clusters as suggested by some models.
Additionally, we discuss the possible existence of ultra-compact dwarfs around
the isolated elliptical NGC 3962.
