Detailed Calculation of Primordial Black Hole Formation During First-Order Cosmological Phase Transitions

Understand

Primordial black holes could potentially form during a first-order cosmological phase transition due to a build-up of particles which are predominantly reflected from the advancing bubble walls.

• After discussing the general mechanism, we examine the criteria that need to be satisfied for a black hole to form.
• We then set out the Boltzmann equation that describes the evolution of the relevant phase space distribution function, carefully describing our treatment of the Liouville operator and the collision term.
• Assuming a spherical false vacuum pocket of sufficient size and a constant wall velocity, we find that black holes can form in a range of different scenarios.