Primordial black hole dark matter from catastrogenesis with unstable pseudo-Goldstone bosons

Understand

We propose a new scenario for the formation of asteroid-mass primordial black holes (PBHs).

• Our mechanism is based on the annihilation of the string-wall network associated with the breaking of a $U(1)$ global symmetry into a discrete $Z_N$ symmetry.
• If the potential has multiple local minima ($N>1$) the network is stable, and the annihilation is guaranteed by a bias among the different vacua.
• The collapse of the string-wall network is accompanied by catastrogenesis, a large production of pseudo-Goldstone bosons (pGBs) -- e.g.