Title: Turn up the volume: Listening to hot dark sector phase
transitions
The observation of stochastic gravitational wave backgrounds
from first-order phase transitions in the early Universe is promising to
become a feasible test for high energy physics. In this talk, I will
show how observable signals can be obtained from strong first-order
phase transitions in a dark sector. If the dark sector is initially
without thermal contact to the particle species of the Standard Model
(SM), it is reasonable to assume that it has a higher temperature than
the SM bath during the phase transition. This will, in turn, result in
more energy being emitted in the form of gravitational radiation.
However, the resulting signals will be diluted by the entropy injected
into the SM bath when the hot dark sector decays. To illustrate these
competing effects, I will consider a U(1) extension to the SM that
allows for a phase transition testable with LISA and the Einstein
Telescope.