Nonideal self-gravity and cosmology: the importance of correlations in the dynamics of the large-scale structures of the Universe

TL;DR

This paper explores how correlations in unresolved sub-structures of the Universe's large-scale structures influence cosmic dynamics, potentially explaining accelerated expansion without dark energy.

Contribution

It introduces the importance of correlations in the Virial theorem and extends Friedmann equations to include nonideal effects, offering a new perspective on cosmic acceleration.

Findings

Correlations affect the Virial theorem in self-gravitating systems.

Omission of correlations leads to a missing mass problem.

Correlations may explain the Universe's accelerated expansion.

Abstract

Inspired by the role of correlations in the statistical mechanics of nonideal self-interacting fluids, we suggest that unresolved sub-structures (i.e. correlations) have to be taken into account in the Virial theorem of self-gravitating astrophysical systems. We demonstrate that their omission leads to a missing mass problem by using the semi-analytic polytropic solutions of the Lane-Emden equation. This problem suggests to extend the Friedmann equations to the nonideal regime by taking into account correlations in the dynamics of the expansion. The increase of correlations induced by the formation of the large-scale structures could explain naturally the accelerated expansion of the Universe in such a paradigm.