Gravitational wave signals of early universe axion dynamics

by Francesc Ferrer (Washington University)

Monday 9 Dec 2019, 16:00 → 18:00 Europe/Rome

Aula Conversi (Dip. di Fisica - Edificio G. Marconi)

The detection of gravitational waves from the merger of black holes of several tens of solar masses has reignited the interest of primordial black holes (PBHs) as the source of part of the dark matter in the universe. A small relic abundance of heavy PBHs may play an important role in the generation of cosmological structures, and we will discuss how such a PBH population can be generated by the collapse of axionic topological defects created during the QCD phase transition. Furthermore, some axion-like particle (ALP) models feature a strong first order phase transition at a high energy scale, ~f_a. We will show how future gravitational-wave experiments can probe the ALP parameter space in a way that is complementary to current laboratory and astrophysical searches.