Abstract: The acceleration of the expansion of the Universe may be due to either a new matter component, dark energy, or a modification of gravity on large scales. In fact, modifying gravity always involves a scalar degree of freedom which can lead to dark energy. Locally, in the solar system, gravity is extremely well described by General Relativity. Hence any modification of gravity must have screened effects in our local environment. We review the known screening mechanisms: chameleon, K-mouflage and Vainshtein. For the chameleon mechanism as exemplified by f (R) models, the local tests imply that the effective equation of state of dark energy is very close to -1 in the late time Universe. For Galileons with the Vainshtein mechanism, self-acceleration is possible with a varying equation of state. In both cases, modifications of gravity are accompanied by a change in the growth of structure.
Publication Year: 2011
Publication Date: 2011-01-01
Language: en
Type: article
Access and Citation
AI Researcher Chatbot
Get quick answers to your questions about the article from our AI researcher chatbot