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Title: Computing model independent perturbations in dark energy and modified gravity

We present a methodology for computing model independent perturbations in dark energy and modified gravity. This is done from the Lagrangian for perturbations, by showing how field content, symmetries, and physical principles are often sufficient ingredients for closing the set of perturbed fluid equations. The fluid equations close once ''equations of state for perturbations'' are identified: these are linear combinations of fluid and metric perturbations which construct gauge invariant entropy and anisotropic stress perturbations for broad classes of theories. Our main results are the proof of the equation of state for perturbations presented in a previous paper, and the development of the required calculational tools.
Authors:
 [1] ;  [2]
  1. Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, The University of Manchester, Manchester M13 9PL (United Kingdom)
  2. Department of Mathematical Sciences, Durham University, South Road, Durham, DH1 3LE (United Kingdom)
Publication Date:
OSTI Identifier:
22370603
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2014; Journal Issue: 03; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ANISOTROPY; DISTURBANCES; ENTROPY; EQUATIONS OF STATE; GAUGE INVARIANCE; GRAVITATION; LAGRANGIAN FUNCTION; METRICS; NONLUMINOUS MATTER; PERTURBATION THEORY; SYMMETRY