van de Bruck, C. and Sculthorpe, G. (2013) Modified Gravity and the Radiation Dominated Epoch. Physical Review D , 87 (4). 044004. ISSN 1550-7998
Abstract
In this paper we consider scalar-tensor theories, allowing for both conformal and disformal couplings to a fluid with a general equation of state. We derive the effective coupling for both background cosmology and for perturbations in that fluid. As an application we consider the scalar degree of freedom to be coupled to baryons and study the dynamics of the tightly coupled photon-baryon fluid in the early Universe. We derive an expression for the effective speed of sound, which differs from its value in General Relativity. We apply our findings to the μ-distortion of the cosmic microwave background radiation, which depends on the effective sound-speed of the photon-baryon fluid, and show that the predictions differ from General Relativity. Thus, the μ-distortion provides further information about gravity in the very early Universe well before decoupling.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2013 American Physical Society. This is an author produced version of a paper subsequently published in Physical Review D. Uploaded in accordance with the publisher's self-archiving policy. |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Science (Sheffield) > School of Mathematics and Statistics (Sheffield) |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 19 Sep 2016 15:15 |
Last Modified: | 28 Mar 2018 18:05 |
Published Version: | http://dx.doi.org/10.1103/PhysRevD.87.044004 |
Status: | Published |
Publisher: | American Physical Society |
Refereed: | Yes |
Identification Number: | 10.1103/PhysRevD.87.044004 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:99113 |