Primordial Sources of Gravitational Waves in Early Universe

Topic I (1 week): Preliminaries of Gravitational Waves (GW) in general relativity

GWs in linearized gravity, propagation of GWs in the expanding Universe, stochastic GW backgrounds in cosmology, Preliminaries of GW experiments primer: GW interferometers and pulsar timing arrays

Topic II (3 weeks): GW & Primordial Black Holes from inflationary cosmology

Cosmic microwave background (CMB), tensor perturbations and BB-modes and tensor-to-scalar ratio, Integrated GW energy density, amplification of primordial tensor perturbations during inflation, transfer function, second-order GW and Primordial Black Holes.

Topic III (1 week): GW from strong first-order phase transitions in the early Universe and particle physics models

Topic IV (1 week): GWs from cosmic topological defects in the early Universe

Introduction to topological defects, GW signal from a network of defects: cosmic strings, domain walls, texture and monopoles

Topic V (1 week): Pulsar TIming Array signal, possible new physics interpretations

Introduction and overview of PTA measurement, possible astrophysical and cosmological new physics interpretations, upcoming data and future

Examination: Presentation of topics assigned to student at the end of the course

(20 min presentation + question/answer)