A new mechanism for primordial black hole formation during a cosmological first-order phase transition

Synopsis

In this talk, I will discuss a recently proposed new mechanism for the formation of primordial black holes. According to this mechanism, the walls separating the two phases of a first-order cosmological phase transition are almost impermeable to some particle species. As the new phase expands, these particles are pushed ahead of the walls and remain trapped within the shrinking regions of the previous phase. Consequently, at the end of the phase transition, this process could lead to energy densities that can trigger black hole formation.