Computing model independent perturbations in dark energy and modified gravity

Abstract

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.

typos corrected; updated to match version in JCAP

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Cited by in corpus (23)

• Beyond the Cosmological Standard Model
• Cosmological Tests of Modified Gravity
• Maximal freedom at minimum cost: linear large-scale structure in general modifications of gravity
• Effective Field Theory of Cosmic Acceleration: an implementation in CAMB
• Effective Field Theory of Cosmic Acceleration: constraining dark energy with CMB data
• Effective Description of Higher-Order Scalar-Tensor Theories
• The Observational Future of Cosmological Scalar-Tensor Theories
• The Novel Probes Project -- Tests of Gravity on Astrophysical Scales
• A comparison of Einstein-Boltzmann solvers for testing General Relativity
• A general theory of linear cosmological perturbations: scalar-tensor and vector-tensor theories
• Gravitational wave constraints on dark sector models
• An extensive investigation of the Generalised Dark Matter model
• Weakening Gravity on Redshift-Survey Scales with Kinetic Matter Mixing
• f(R) as a dark energy fluid
• Cosmological perturbation theory in Generalized Einstein-Aether models
• Comparison of different approaches to the quasi-static approximation in Horndeski models
• Do cosmological data rule out $f(\mathcal{R})$ with $w\ne -1$?
• A general theory of linear cosmological perturbations: bimetric theories
• Constraining dark sector perturbations I: cosmic shear and CMB lensing
• Cosmologically viable generalized Einstein-Aether theories
• Dark sector evolution in Horndeski models
• Constraining dark sector perturbations II: ISW and CMB lensing tomography
• Cosmological perturbations in generalised dark Lagrangians