Star Cluster collisions - a formation scenario for the Extended Globular
  Cluster Scl-dE1 GC1
  Recent observations of the dwarf elliptical galaxy Scl-dE1 (Sc22) in the
Sculptor group of galaxies revealed an extended globular cluster (Scl-dE1 GC1),
which exhibits an extremely large core radius of about 21.2 pc. The authors of
the discovery paper speculated on whether this object could reside in its own
dark matter halo and/or if it might have formed through the merging of two or
more star clusters. In this paper, we present N-body simulations to explore
thoroughly this particular formation scenario. We follow the merger of two star
clusters within dark matter haloes of a range of masses (as well as in the
absence of a dark matter halo). In order to obtain a remnant which resembles
the observed extended star cluster, we find that the star formation efficiency
has to be quite high (around 33 per cent) and the dark matter halo, if present
at all, has to be of very low mass, i.e. raising the mass to light ratio of the
object within the body of the stellar distribution by at most a factor of a
few. We also find that expansion of a single star cluster following mass loss
provides another viable formation path. Finally, we show that future
measurements of the velocity dispersion of this system may be able to
distinguish between the various scenarios we have explored.
