Chameleon screening in cosmic voids

Tamosiunas, Andrius; Briddon, Chad; Burrage, Clare; Cutforth, Alan; Moss, Adam; Vincent, Thomas

Abstract

A key goal in cosmology in the upcoming decade will be to form a better understanding of the accelerated expansion of the Universe. Upcoming surveys, such as the Vera C. Rubin Observatory's 10-year Legacy Survey of Space and Time (LSST), Euclid and the Square Killometer Array (SKA) will deliver key datasets required to tackle this and other puzzles in contemporary cosmology. With this data, constraints of unprecedented power will be put on different models of dark energy and modified gravity. In this context it is crucial to understand how screening mechanisms, which hide the deviations of these theories from the predictions of general relativity in local experiments, affect structure formation. In this work we approach this problem by using a combination of analytic and numerical methods to describe chameleon screening in the context of cosmic voids. We apply a finite element method (FEM) code, SELCIE, to solve the chameleon equation of motion for a number of void profiles derived from observational data and simulations. The obtained results indicate a complex relationship between the properties of cosmic voids and the size of the chameleon acceleration of a test particle. We find that the fifth force on a test particle in a void is primarily related to the depth and the inner density gradient of the void. For realistic void profiles, the obtained chameleon-to-Newtonian acceleration ratios range between aϕ /aNewt ≈ 10-6– 10-5. However, it should be noted that in unusually deep voids with large inner density gradients, the acceleration ratios can be significantly higher. Similarly, other chameleon models, such as f(R) Hu-Sawicki theory allow for significantly higher acceleration ratios. Given these results, we also discuss the optimal density profiles for detecting the fifth force in the upcoming observational surveys.

Citation

Tamosiunas, A., Briddon, C., Burrage, C., Cutforth, A., Moss, A., & Vincent, T. (2022). Chameleon screening in cosmic voids. Journal of Cosmology and Astroparticle Physics, 2022(11), Article 056. https://doi.org/10.1088/1475-7516/2022/11/056

• Journal Article Type: Article
• Acceptance Date: Nov 15, 2022
• Online Publication Date: Nov 28, 2022
• Publication Date: Nov 1, 2022
• Deposit Date: Jan 5, 2023
• Publicly Available Date: Jan 5, 2023
• Journal: Journal of Cosmology and Astroparticle Physics
• Electronic ISSN: 1475-7516
• Peer Reviewed: Peer Reviewed
• Volume: 2022
• Issue: 11
• Article Number: 056
• DOI: https://doi.org/10.1088/1475-7516/2022/11/056
• Keywords: paper, gravity, modified gravity, dark energy theory, cosmic web
• Public URL: https://nottingham-repository.worktribe.com/output/14588182
• Publisher URL: https://iopscience.iop.org/article/10.1088/1475-7516/2022/11/056
• Additional Information: Article Title: Chameleon screening in cosmic voids; Journal Title: Journal of Cosmology and Astroparticle Physics; Article Type: paper; Copyright Information: © 2022 The Author(s); Date Received: 2022-07-05; Date Accepted: 2022-11-15; Online publication date: 2022-11-28