The Role of Effective Gravitational Interactions for Reheating and Cosmological Relics

Cosmic inflation successfully explains the origin of primordial cosmological perturbations, but requires an efficient reheating mechanism to populate the Universe with radiation and matter. In this seminar, I study reheating driven by perturbative, Planck-suppressed effective gravitational interactions during inflaton oscillations. I first focus on graviton-mediated portals and non-minimal couplings to gravity, and analyze the gravitational production of particles for the generation of heavy dark matter relics, the baryon asymmetry via non-thermal leptogenesis, and potential GW signals. I show that these unavoidable gravitational effects can significantly impact reheating dynamics and yield the observed relic abundances. I conclude by discussing the associated stochastic gravitational wave signals, highlighting their potential as probes of spectator fields and gravitational particle production in the post-inflationary Universe.