A Gravitational Wave Background from Reheating after Hybrid Inflation

Understand

The reheating of the universe after hybrid inflation proceeds through the nucleation and subsequent collision of large concentrations of energy density in the form of bubble-like structures moving at relativistic speeds.

• This generates a significant fraction of energy in the form of a stochastic background of gravitational waves, whose time evolution is determined by the successive stages of reheating: First, tachyonic preheating makes the amplitude of gravity waves grow exponentially fast.
• Second, bubble collisions add a new burst of gravitational radiation.
• Third, turbulent motions finally sets the end of gravitational waves production.