Cosmological Perturbations: Vorticity, Isocurvature and Magnetic Fields

Understand

In this paper I review some recent, interlinked, work undertaken using cosmological perturbation theory -- a powerful technique for modelling inhomogeneities in the Universe.

• The common theme which underpins these pieces of work is the presence of non-adiabatic pressure, or entropy, perturbations.
• After a brief introduction covering the standard techniques of describing inhomogeneities in both Newtonian and relativistic cosmology, I discuss the generation of vorticity.
• As in classical fluid mechanics, vorticity is not present in linearized perturbation theory (unless included as an initial condition).