Perturbation Theory of the Cosmological Log-Density Field

Understand

The matter density field exhibits a nearly lognormal probability density distribution (PDF) after entering into the nonlinear regime.

• Recently, it has been shown that the shape of the power spectrum of a logarithmically transformed density field is very close to the linear density power spectrum, motivating an analytic study of it.
• In this paper, we develop cosmological perturbation theory for the power spectrum of this field.
• Our formalism is developed in the context of renormalized perturbation theory, which helps to regulate the convergence behavior of the perturbation series, and of the Taylor- series expansion we use of the logarithmic mapping.