Cosmological Perturbations with Multiple Fluids and Fields
Abstract
We consider the evolution of perturbed cosmological spacetime with multiple fluids and fields in Einstein gravity. Equations are presented in gauge-ready forms, and are presented in various forms using the curvature ( or φ) and isocurvature (S(ij) or δ φ(ij)) perturbation variables in the general background with K and . We clarify the conditions for conserved curvature and isocurvature perturbations in the large-scale limit. Evolutions of curvature perturbations in many different gauge conditions are analysed extensively. In the multi-field system we present a general solution to the linear order in slow-roll parameters.
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