Περίληψη :
The primordial gravitational-wave background (PGWB), if detected, would provide key information about the inflationary period, complementary to the scalar perturbations already measured in the CMB. Typically, the PGWB is decoupled from scalar perturbations during inflation; however, if the inflaton undergoes a phase of strong non-linear evolution, as can occur in axion-monodromy and ultra-slow-roll models, tensors and scalars can interact strongly, producing a rich observational phenomenology. We use the numerical relativity code GRChombo to predict the shape of the PGWB by evolving a stochastic gravitational-wave background according to the fully relativistic Einstein’s equations during inflation. I will present the methodology and validation of our GRChombo example, which initialises a stochastic background according to the linearised Mukhanov-Sasaki solution for a massless scalar field and extracts the non-Gaussian statistics of this background before, during and after horizon crossing.
