Sussing Merger Trees: the influence of the halo finder
  Merger tree codes are routinely used to follow the growth and merger of dark
matter haloes in simulations of cosmic structure formation. Whereas in Srisawat
et. al. we compared the trees built using a wide variety of such codes here we
study the influence of the underlying halo catalogue upon the resulting trees.
We observe that the specifics of halo finding itself greatly influences the
constructed merger trees. We find that the choices made to define the halo mass
are of prime importance. For instance, amongst many potential options different
finders select self-bound objects or spherical regions of defined overdensity,
decide whether or not to include substructures within the mass returned and
vary in their initial particle selection. The impact of these decisions is seen
in tree length (the period of time a particularly halo can be traced back
through the simulation), branching ratio (essentially the merger rate of
\subhalos) and mass evolution. We therefore conclude that the choice of the
underlying halo finder is more relevant to the process of building merger trees
than the tree builder itself. We also report on some built-in features of
specific merger tree codes that (sometimes) help to improve the quality of the
merger trees produced.
