Topical Seminar. The Nano-Hertz Gravitational Wave Background: Connection to sub-GeV dark matter

por Dr. Carlo Tasillo (Uppsala University)

jueves 16 oct. 2025 12:00 → 13:00 Europe/Madrid

1001-Primera-1-1-1 - Paterna. Seminario (Universe)

Pulsar timing arrays (PTAs) have recently uncovered evidence for a nano-Hertz gravitational wave background. While supermassive black hole binaries are the leading astrophysical explanation, they may not tell the full story. A strong first-order phase transition in the early universe could provide the missing piece – if it also passes the stringent tests from cosmology, colliders, and dark matter searches.

In my talk, I will focus on one predictive scenario [arXiv:2502.19478] that links the PTA signal to the freeze-out production of sub-GeV dark matter after the phase transition. As I will show, this scenario offers a unique possibility to be tested with the next generation of beam-dump experiments. I will close with an outlook on PTA science and research directions for my upcoming fellowship at IFIC.