Cosmological Magnetogenesis : A gauge-invariant approach

Astrophysical observations indicate that almost all environments in the Universe are magnetized, and the more we search for extragalactic fields, the more pervading they are revealed to be. The next logical step is to ask why these large-scale magnetic fields are ubiquitous in a Universe as diverse as ours and how did these fields originate? This thesis attempts to answer this question, using second-order gauge-invariant perturbation theory to develop a self-consistent framework in which the non-linear coupling between inflationary gravitational waves and primordial large-scale magnetic fields can be studied. The magnetic-gravito interaction is shown to produce a sufficient amplification of both a homogeneous and inhomogeneous magnetic field to within the strength limits required to support the galactic dynamo.