Spin of primordial black holes in the model with collapsing domain walls

Understand

The angular momentum (spin) acquisition by a collapsing domain wall at the cosmological radiation-dominated stage is investigated.

• During the collapses, primordial black holes and their clusters can be born in various mass ranges.
• Spin accumulation occurs under the influence of tidal gravitational perturbations from the surrounding density inhomogeneities at the epoch when the domain wall crosses the cosmological horizon.
• It is shown that the dimensionless spin parameter can have the small values $a_S<1$ only for primordial black holes with masses $M>10^{-3}M_\odot$, whereas less massive black holes receive extreme spins $a_S\simeq1$.