Isolated dark matter deprived galaxies in hydrodynamical simulations:
  real objects or artefacts?
  We searched for isolated dark matter deprived galaxies within several
state-of-the-art hydrodynamical simulations: Illustris, IllustrisTNG, EAGLE,
and Horizon-AGN and found a handful of promising objects in all except
Horizon-AGN. While our initial goal was to study their properties and
evolution, we quickly noticed that all of them were located at the edge of
their respective simulation boxes. After carefully investigating these objects
using the full particle data, we concluded that they are not merely caused by a
problem with the algorithm identifying bound structures. We provide strong
evidence that these oddballs were created from regular galaxies that get torn
apart due to unphysical processes when crossing the edge of the simulation box.
We show that these objects are smoking guns indicating an issue with the
implementation of the periodic boundary conditions of the particle data in
Illustris, IllustrisTNG, and EAGLE, which was eventually traced down to be a
minor bug occurring for a very rare set of conditions.
