01/11 2022 Seminar
- Title题目 Gravitational wave from first order phase transition during inflation
- Speaker报告人 Siyi Zhou (Kobe University)
- Date日期 2022年01月11日 14:30
- Venue地点 Join Zoom Meeting https://zoom.us/j/88352719940?pwd=T1JTRGVRYWZ1S1VqMFU3SVVIQk5jdz09 Meeting ID: 883 5271 9940 Passcode: 140261
Large excursion of the inflaton field can trigger interesting dynamics. One important example is a first order phase transition in a spectator sector which couples to the inflaton. Gravitational waves (GWs) from a first order phase transition during inflation, which is an example of an instantaneous source, has an oscillatory feature. This feature is generic for the source to happen in a universe experiencing accelerating expansion. The shape of the GW signal contains information about the evolution of the early universe following the phase transition. In particular, the slope of the infrared part of the GW spectrum is sensitive to the evolution of the Hubble parameter when the GW modes reenter the horizon after inflation, the slope of the profile of the intermediate oscillatory part depends on both the evolutions of the Hubble parameter when the modes reenter the horizon and the Hubble parameter when the modes exit the horizon during inflation, and the slope of the ultraviolet part depends on the evolutions of the Hubble parameter when the modes reenter the horizon and the Hubble parameter when the modes exit the horizon during inflation, and the details of the of the dynamics of the phase transition. We consider several examples of non-minimal models of evolution during and after the inflation, and we demonstrate that shape of the GW can be used to distinguishing them from the minimal scenario of quasi-de Sitter inflation and radiation domination after a fast reheating.