Symmetron scalar fields: modified gravity, dark matter, or both?

Burrage, Clare; Copeland, Edmund J.; K�ding, Christian; Millington, Peter

Abstract

Scalar fields coupled to gravity through the Ricci scalar have been considered both as dark matter candidates and as a possible modified gravity explanation for galactic dynamics. It has recently been demonstrated that the dynamics of baryonic matter in disk galaxies may be explained, in the absence of particle dark matter, by a symmetron scalar field that mediates a fifth force. The symmetron provides a concrete and archetypal field theory within which to explore how large a role modifications of gravity can play on galactic scales. In this article, we extend these previous works by asking whether the same symmetron field can explain the difference between the baryonic and lens masses of galaxies through a modification of gravity. We consider the possibilities for minimal modifications of the model and find that this difference cannot be explained entirely by the symmetron fifth force without extending the field content of the model. Instead, we are pushed toward a regime of parameter space where one scalar field both mediates a fifth force and stores enough energy density that it also contributes to the galaxy’s gravitational potential as a dark matter component, a regime which remains to be fully explored.

Citation

Burrage, C., Copeland, E. J., Käding, C., & Millington, P. (2019). Symmetron scalar fields: modified gravity, dark matter, or both?. Physical Review D, 99(4), Article 043539. https://doi.org/10.1103/physrevd.99.043539

• Journal Article Type: Article
• Acceptance Date: Jan 17, 2019
• Online Publication Date: Feb 25, 2019
• Publication Date: Feb 15, 2019
• Deposit Date: Apr 4, 2019
• Publicly Available Date: Apr 4, 2019
• Journal: Physical Review D
• Print ISSN: 2470-0010
• Electronic ISSN: 2470-0029
• Publisher: American Physical Society
• Peer Reviewed: Peer Reviewed
• Volume: 99
• Issue: 4
• Article Number: 043539
• DOI: https://doi.org/10.1103/physrevd.99.043539
• Keywords: Physics and Astronomy (miscellaneous)
• Public URL: https://nottingham-repository.worktribe.com/output/1584566
• Publisher URL: https://journals.aps.org/prd/abstract/10.1103/PhysRevD.99.043539
• Additional Information: Symmetron scalar fields: modified gravity, dark matter, or both?, Clare Burrage, Edmund J. Copeland, Christian Käding, and Peter Millington. Physical Review D 99, 043539 (2019)