Vorticity generation at second order in cosmological perturbation theory

TL;DR

This paper demonstrates that in cosmological perturbation theory, vorticity can be generated at second order due to entropy gradients, extending Crocco's theorem to the universe's evolution.

Contribution

It introduces the extension of Crocco's theorem to cosmology, showing entropy gradients as a source of vorticity at second order in perturbation theory.

Findings

Vorticity is generated by entropy gradients at second order.

Extension of Crocco's theorem to cosmological context.

Vorticity generation is a second-order effect in perturbation theory.

Abstract

We show that at second order in cosmological perturbation theory vorticity generation is sourced by entropy gradients. This is an extension of Crocco's theorem to a cosmological setting.