Ultra-Light Scalar Fields and the Growth of Structure in the Universe

TL;DR

This paper investigates how ultra-light scalar fields influence the universe's expansion and structure formation, identifying different evolutionary regimes and potential observational signatures.

Contribution

It characterizes the regimes of ultra-light scalar field evolution and their impact on cosmic expansion and structure growth, providing insights into their observational consequences.

Findings

Different regimes of scalar field evolution identified

Effects on expansion rate and perturbation growth analyzed

Potential observational signatures discussed

Abstract

Ultra-light scalar fields, with masses of between m=10^{-33} eV and m=10^{-22} eV, can affect the growth of structure in the Universe. We identify the different regimes in the evolution of ultra-light scalar fields, how they affect the expansion rate of the universe and how they affect the growth rate of cosmological perturbations. We find a number of interesting effects, discuss how they might arise in realistic scenarios of the early universe and comment on how they might be observed.