Emergent cosmological expansion in scalar–tensor theories of gravity

We consider the emergence of large-scale cosmological expansion in scalar–tensor theories of gravity. This is achieved by modelling sub-horizon regions of space-time as weak-field expansions around Minkowski space, and then subsequently joining many such regions together to create a statistically ho...

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Bibliographic Details
Published inClassical and quantum gravity Vol. 42; no. 1; pp. 15013 - 15029
Main Authors Briddon, Chad, Clifton, Timothy, Fleury, Pierre
Format Journal Article
LanguageEnglish
Published IOP Publishing 03.01.2025
Subjects
chameleon screening
cosmological expansion
relativity
scalar–tensor gravity
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Summary:We consider the emergence of large-scale cosmological expansion in scalar–tensor theories of gravity. This is achieved by modelling sub-horizon regions of space-time as weak-field expansions around Minkowski space, and then subsequently joining many such regions together to create a statistically homogeneous and isotropic cosmology. We find that when the scalar field can be treated perturbatively, the cosmological behaviour that emerges is well modelled by the Friedmann solutions of the theory. When non-perturbative screening mechanisms occur this result no longer holds, and in the case of scalar fields subject to the chameleon mechanism we find significant deviations from the expected Friedmann behaviour. In particular, the screened mass no longer contributes to the Klein–Gordon equation, suppressing deviations from general relativistic behaviour.
Bibliography:CQG-111779.R1
ISSN:0264-9381
1361-6382
DOI:10.1088/1361-6382/ad9880