Phase-transition sound of inflation at gravitational waves detectors

TL;DR

This paper explores how a first-order phase transition during primordial inflation produces a distinctive, reddened gravitational wave spectrum, offering a new observational signature for inflation in gravitational wave data.

Contribution

It demonstrates that phase transitions during inflation leave a unique reddened GW spectrum, providing a novel way to probe inflationary physics through gravitational wave detection.

Findings

The GW spectrum from inflationary phase transitions is reddened.

GW detectors can potentially identify this unique spectrum.

The spectrum serves as a voiceprint of inflation.

Abstract

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.