Title：Primordial black holes spin from cosmological first-order phase transitions
Abstract：
The stochastic bubble nucleation during cosmological first-order phase transitions leads to variations in the phase transition initiation times across different Hubble volumes, thereby generating non-Gaussian density perturbations in regions with delayed transitions. Based on the accumulation mechanism,the false vacuum island model, this paper investigates the spin angular momentum of primordial black holes formed from nonspherical collapse. By introducing the nucleation history integration method, without assuming a Gaussian distribution, we calculate the expectation values and variances of the semi-axis lengths of overdense ellipsoidal regions, combined with the statistical properties of the velocity shear tensor, we derive the quantitative relationship between the Kerr parameter describing black hole spin and the phase transition parameters , latent heat strength and phase transition rate. The study finds that the Kerr parameter increases with latent heat strength and decreases with FOPT rate, at the typical CMB-distortion energy scale, the magnitude of Kerr parameter can reach 10^-3, which is significantly higher than that of PBH formed in radiation-dominated era under peak theory, but still lower than that in a matter-dominated era.
报告人：郝宇诗（清华大学）