Thermal inflation and the gravitational wave background

Abstract

We consider the impact of thermal inflation—a short, secondary period of inflationthat can arise in supersymmetric scenarios—on the stochastic gravitational wavebackground. We show that while the primordial inflationary gravitational wavebackground is essentially unchanged at cosmic microwave background scales, it ismassively diluted at solar system scales and would be unobservable by a Big BangObserver (BBO) style experiment. Conversely, bubble collisions at the end ofthermal inflation can generate a new stochastic background. We calculate the likelyproperties of the bubbles created during this phase transition, and show thatthe expected amplitude and frequency of this signal would fall within the BBOrange.