The Outer Stellar Halos of Galaxies: how Radial Merger Mass Deposition,
  Shells and Streams depend on Infall-Orbit Configurations
  Galaxy mergers are a fundamental part of galaxy evolution. To study the
resulting mass distributions of different kinds of galaxy mergers, we present a
simulation suite of 36 high-resolution isolated merger simulations, exploring a
wide range of parameter space in terms of mass ratios (mu = 1:5, 1:10, 1:50,
1:100) and orbital parameters. We find that mini mergers deposit a higher
fraction of their mass in the outer halo compared to minor mergers, while their
contribution to the central mass distribution is highly dependent on the
orbital impact parameter: for larger pericentric distances we find that the
centre of the host galaxy is almost not contaminated by merger particles. We
also find that the median of the resulting radial mass distribution for mini
mergers differs significantly from the predictions of simple theoretical
tidal-force models. Furthermore, we find that mini mergers can increase the
size of the host disc significantly without changing the global shape of the
galaxy, if the impact occurs in the disc plane, thus providing a possible
explanation for extended low-surface brightness disks reported in observations.
Finally, we find clear evidence that streams are a strong indication of nearly
circular infall of a satellite (with large angular momentum), whereas the
appearance of shells clearly points to (nearly) radial satellite infall.
