SELCIE: a tool for investigating the chameleon field of arbitrary sources

Briddon, Chad; Burrage, Clare; Moss, Adam; Tamosiunas, Andrius

Abstract

The chameleon model is a modified gravity theory that introduces an additional scalar field that couples to matter through a conformal coupling. This `chameleon field' possesses a screening mechanism through a nonlinear self-interaction term which allows the field to affect cosmological observables in diffuse environments whilst still being consistent with current local experimental constraints. Due to the self-interaction term the equations of motion of the field are nonlinear and therefore difficult to solve analytically. The analytic solutions that do exist in the literature are either approximate solutions and or only apply to highly symmetric systems. In this work we introduce the software package SELCIE (https://github.com/C-Briddon/SELCIE.git). This package equips the user with tools to construct an arbitrary system of mass distributions and then to calculate the corresponding solution to the chameleon field equation. It accomplishes this by using the finite element method and either the Picard or Newton nonlinear solving methods. We compared the results produced by SELCIE with analytic results from the literature including discrete and continuous density distributions. We found strong (sub-percentage) agreement between the solutions calculated by SELCIE and the analytic solutions.

Citation

Briddon, C., Burrage, C., Moss, A., & Tamosiunas, A. (2021). SELCIE: a tool for investigating the chameleon field of arbitrary sources. Journal of Cosmology and Astroparticle Physics, 2021(12), 1-24. https://doi.org/10.1088/1475-7516/2021/12/043

• Journal Article Type: Article
• Acceptance Date: Nov 26, 2021
• Online Publication Date: Dec 21, 2021
• Publication Date: 2021-12
• Deposit Date: Jan 4, 2022
• Publicly Available Date: Jan 4, 2022
• Journal: Journal of Cosmology and Astroparticle Physics
• Electronic ISSN: 1475-7516
• Publisher: IOP Publishing
• Peer Reviewed: Peer Reviewed
• Volume: 2021
• Issue: 12
• Article Number: 043
• Pages: 1-24
• DOI: https://doi.org/10.1088/1475-7516/2021/12/043
• Keywords: modified gravity, dark energy theory, dark energy experiments
• Public URL: https://nottingham-repository.worktribe.com/output/7162828
• Publisher URL: https://iopscience.iop.org/article/10.1088/1475-7516/2021/12/043
• Additional Information: Article Title: SELCIE: a tool for investigating the chameleon field of arbitrary sources; Journal Title: Journal of Cosmology and Astroparticle Physics; Article Type: paper; Copyright Information: © 2021 The Author(s); Date Received: 2021-11-11; Date Accepted: 2021-11-26; Online publication date: 2021-12-21