Acceleration from Modified Gravity: Lessons from Worked Examples

Abstract

I examine how two specific examples of modified gravity explanations of cosmic acceleration help us understand some general problems confronting cosmological tests of gravity: how do we distinguish modified gravity from dark energy if they can be made formally equivalent? how do we parameterize deviations according to physical principles with sufficient generality, yet focus cosmological tests into areas that complement our existing knowledge of gravity? how do we treat the dynamics of modifications which necessarily involve non-linearities that preclude superposition of forces? The modified action f(R) and DGP braneworld models provide insight on these question as fully-worked examples whose expansion history, linear perturbation theory, and most recently, non-linear N-body and force-modification field dynamics of cosmological simulations are available for study.

8 pages, 1 figure, Nuclear Physics B, GGI Proceedings

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Cited by in corpus (14)

• Cosmological Tests of Modified Gravity
• Spherical Collapse and the Halo Model in Braneworld Gravity
• A Unified Approach to Cosmic Acceleration
• Galaxy Infall Kinematics as a Test of Modified Gravity
• The Vainshtein Mechanism in the Cosmic Web
• Equivalence Principle Violation in Vainshtein Screened Two-Body Systems
• Testing Brans-Dicke Gravity with Screening by Scalar Gravitational Wave Memory
• $\text{Hi-COLA}$: Fast, approximate simulations of structure formation in Horndeski gravity
• Consistency check of ΛCDM phenomenology
• Unmodified Gravity
• About matter and dark-energy domination eras in R^n gravity or lack thereof
• Equivalence Principle Violation in Weakly Vainshtein-Screened Systems
• Gravitational couplings in Chameleon models
• The Distinguishability of Interacting Dark Energy from Modified Gravity