Phase-transition sound of inflation at gravitational waves detectors

Understand

It is well-known that the first-order phase transition (PT) will yield a stochastic gravitational waves (GWs) background with a logo-like spectrum.

• However, we show that when such a PT happened during the primordial inflation, the GWs spectrum brought by the PT will be reddened, which thus records the unique voiceprint of inflation.
• We assess the abilities of the GW detectors to detect the corresponding signal.