Speaker
Description
Supercooled phase transitions have attracted significant interest as potential sources of strong, low-frequency gravitational wave signals detectable by Pulsar Timing Arrays (PTAs). A nucleation temperature $T_n$ is often used to characterize the onset of the transition, defined by a threshold on the nucleation rate. However, in the regime of ultra-low nucleation rates, $T_n$ may not exist, but this does not necessarily imply that the transition cannot complete. We show that even when nucleation remains suppressed and bubble separations exceed the Hubble scale, early-time bubbles can grow and eventually collide at late times, leading to completion. This presentation focuses on the completion condition and the associated dynamics in the regime of ultra-low nucleation rates.
