On Ellipsoidal Collapse and Primordial Black-Hole Formation
  We reinvestigate gravitational ellipsoidal collapse with special focus on its impact on primordial black-hole formation. For a generic model we demonstrate that the abundance and energy density of the produced primordial black holes will be significantly decreased when the non-sphericity of the overdensities is taken into account. 
Florian Kuhnel and Marit Sandstad
astro-ph.CO gr-qc