Seminar: Primordial black holes from Q-balls

Speaker: Shunsuke Neda (ICRR, Univ. of Tokyo)

Venue & Time: Red Room / 15:00

Title: Primordial black holes from Q-balls

Abstract: 

We discuss primordial black holes (PBHs) originating from Q-balls, which are non-topological solitons arising in complex scalar field theories with a global U(1) symmetry. Depending on the cosmic expansion history, Q-balls can source PBH formation in both early matter-dominated (eMD) and radiation-dominated (RD) universes, leading to distinct phenomenological consequences.

In the eMD scenario, PBHs produced from Q-balls can account for the observed dark matter abundance, and we summarize the resulting cosmological constraints. In contrast, some scenarios of PBHs formed in a radiation-dominated universe exhibit strong PBH clustering. When motivated as seeds of supermassive black holes, their abundance and spatial distribution are observationally constrained by isocurvature perturbations. For stellar-mass PBHs relevant to LIGO-Virgo-KAGRA, we compute PBH merger rates in the presence of initial PBH clustering using updated methodologies.

This seminar illustrates how PBHs from Q-balls link particle physics models to cosmological, astrophysical, and gravitational-wave observations across multiple mass scales.