Self-gravitating $\Lambda$-media

TL;DR

This paper investigates whether a medium with pressure equal to negative density must be a cosmological constant, showing through effective field theory that various media can exhibit such properties with distinguishable observational signatures.

Contribution

It demonstrates that $ ext{p} + ho = 0$ media are not necessarily cosmological constants, providing explicit models and identifying observational differences.

Findings

$ ext{p} + ho = 0$ media are not always cosmological constants

Explicit constructions for perfect fluids, solids, and super solids

Lensing and structure growth can distinguish these media from true cosmological constants

Abstract

We address the question whether a medium featuring $p + \rho = 0$, dubbed $\Lambda$- medium, has to be necessarily a cosmological constant. By using effective field theory, we show that this is not the case for a class of media comprising perfect fluids, solids and special super solids, providing an explicit construction. The low energy excitations are non trivial and lensing, the growth of large scale structures can be used to clearly distinguish $\Lambda$-media from a cosmological constant.