First Test of High Frequency Gravity Waves from Inflation using ADVANCED LIGO

TL;DR

This paper explores the potential for Advanced LIGO to detect high-frequency gravitational waves generated by bubble collisions during a first order phase transition at the end of inflation, providing a new observational window into early universe physics.

Contribution

It demonstrates that Advanced LIGO can test specific inflationary models involving first order phase transitions through gravitational wave signatures.

Findings

Advanced LIGO can probe inflationary energy scales between 10^7 and 10^{10} GeV.

Detectable GW signals depend on parameters ε and χ related to the phase transition.

Potential first detection of inflationary gravitational waves at high frequencies.

Abstract

Inflation models ending in a first order phase transition produce gravitational waves (GW) via bubble collisions of the true vacuum phase. We demonstrate that these bubble collisions can leave an observable signature in Advanced LIGO, an upcoming ground-based GW experiment. These GW are dependent on two parameters of the inflationary model: $\varepsilon$ represents the energy difference between the false vacuum and the true vacuum of the inflaton potential, and $\chi$ measures how fast the phase transition ends ($\chi \sim$ the number of e-folds during the actual phase transition). Advanced LIGO will be able to test the validity of single-phase transition models within the parameter space $10^7 \rm{GeV}\lesssim \varepsilon^{1/4} \lesssim 10^{10} \rm{GeV}$ and $0.19 \lesssim \chi \lesssim 1$. If inflation occurred through a first order phase transition, then Advanced LIGO could be the first to discover high frequency GW from inflation.