A Concise Introduction to Perturbation Theory in Cosmology

Understand

We give a concise, self-contained introduction to perturbation theory in cosmology at linear and second order, striking a balance between mathematical rigour and usability.

• In particular we discuss gauge issues and the active and passive approach to calculating gauge transformations.
• We also construct gauge-invariant variables, including the second order tensor perturbation on uniform curvature hypersurfaces.