Gravitational waves from primordial fluctuations

Abstract:
The evolution of primordial fluctuations in the early universe is accompanied by a production of gravitational waves. The so-called induced gravitational waves are the cosmic messenger of primordial fluctuations on the smallest scales, which may have been generated during cosmic inflation. In this talk, I will discuss how they may be used to explore the early universe's initial conditions and expansion history. This includes gravitational waves induced by oscillatory features in the primordial spectrum, early isocurvature fluctuations and a primordial black hole dominated universe.