Speaker
Description
Cosmological first-order phase transitions (FOPT) can occur in a secluded dark sector at relatively late times before recombination. Since bubble nucleation occurs stochastically as the FOPT unfolds, different regions of the universe transition at different times. On large scales, this random fluctuation sources a scalar curvature perturbation with a dimensionless power spectrum that scales independently of the microscopic details of the FOPT. Even though the dark sector interacts with the Standard Model only gravitationally, the generated curvature perturbation can affect various cosmological and astrophysical observables. In this talk, we consider how such an FOPT can be constrained at different scales using CMB and structure formation measurements.