Turnaround size of non-spherical structures
  The turnaround radius of a large structure in an accelerating universe has
been studied only for spherical structures, while real astronomical systems
deviate from spherical symmetry. We show that, for small deviations from
spherical symmetry, the gauge-invariant characterization of the turnaround size
using the Hawking-Hayward quasi-local mass and spherical symmetry still
applies, to first order in the cosmological perturbation potentials and in the
deviations from sphericity. This is the first step to include non-spherical
systems in the physics of turnaround.
