Speaker
Description
A cosmic string-wall network is associated with the breaking of a U(1) global symmetry into a discrete Z(N) symmetry with N>1. Its annihilation due to a small bias between the N minima is accompanied by “catastrogenesis” (from the greek for annihilation), the production of pseudo-Goldstone bosons (pGBs) - e.g. axions, ALPs, or majorons - gravitational waves, and primordial black holes (PBH). The pGBs can be stable, and be the dark matter. But they may be unstable and not contribute to the dark matter population, in which case we show that PBHs can instead constitute 100% of the dark matter for pGBs that decay into products that thermalize in the early Universe. We show that the gravitational wave background produced by catastrogenesis could be observable by cosmological probes or future interferometers.
