Prof. Dr. Pedro Schwaller

In this presentation, we explore the potential of gravitational waves as powerful instruments for investigating new physics in the early Universe. Beginning with a comprehensive overview of the topic's significance, we delve into several noteworthy scenarios that give rise to primordial gravitational waves, specifically highlighting the impact of first-order phase transitions and axion dynamics. Furthermore we report on progress in computing the GW signal from phase transitions in strongly coupled theories using holographic methods. Finally we examine the intriguing observation of a tentative stochastic gravitational wave background at low frequencies using pulsar timing arrays, shedding light on its implications for novel models in the realm of new physics.