Evolution and spherical collapse in Einstein-Æther theory and Hořava gravity

Bhattacharyya, Jishnu; Coates, Andrew; Colombo, Mattia; Sotiriou, Thomas P.

Abstract

We compare the initial value formulation of the low-energy limit of (nonprojectable) Hořava gravity to that of Einstein-æther theory when the æther is assumed to be hypersurface orthogonal at the level of the field equations. This comparison clearly highlights a crucial difference in the causal structure of the two theories at the nonperturbative level: in Hořava gravity evolution equations include an elliptic equation that is not a constraint relating initial data but needs to be imposed on each slice of the foliation. This feature is absent in Einstein-æther theory. We discuss its physical significance in Hořava gravity. We also focus on spherical symmetry, and we revisit existing collapse simulations in Einstein-æther theory. We argue that they have likely already uncovered the dynamical formation of a universal horizon and that they can act as evidence that this horizon is indeed a Cauchy horizon in Hořava gravity.

Citation

Bhattacharyya, J., Coates, A., Colombo, M., & Sotiriou, T. P. (2016). Evolution and spherical collapse in Einstein-Æther theory and Hořava gravity. Physical Review D, 93(6), Article 64056. https://doi.org/10.1103/PhysRevD.93.064056

• Journal Article Type: Article
• Acceptance Date: Feb 1, 2016
• Publication Date: Mar 23, 2016
• Deposit Date: Dec 21, 2016
• Publicly Available Date: Dec 21, 2016
• Journal: Physical Review D
• Print ISSN: 2470-0010
• Electronic ISSN: 2470-0029
• Publisher: American Physical Society
• Peer Reviewed: Peer Reviewed
• Volume: 93
• Issue: 6
• Article Number: 64056
• DOI: https://doi.org/10.1103/PhysRevD.93.064056
• Public URL: https://nottingham-repository.worktribe.com/output/779351
• Publisher URL: http://dx.doi.org/10.1103/PhysRevD.93.064056
• Additional Information: © 2016 American Physical Society
• Contract Date: Dec 21, 2016