A Nonuniform Dark Energy Fluid: Perturbation Equations

Halle, A.; Zhao, H.; Li, B.

Abstract

We propose that galactic dark matter can be described by a nonuniform dark energy fluid. The underlying field is a decaying vector field, which might corresponds to a photon-like but massive particle of 4 degrees of dynamical freedom. We propose a very general Lagrangian for this vector field. The model includes a continuous spectrum of plausible gravity theories, for example, quintessence, f(R), Einstein-Aether, MOND, TeVeS, BSTV, V-Λ theories, and the inflaton scalar field as special cases. We study in detail a special class of models with a fixed norm of the timelike vector field in the physical metric, which includes a nonlinear K4 term and a Ricci scalar term. We derive the Einstein equations in the perturbed form, which are needed for simulating structure growth in an FRW universe to test such theories. A special case of the model V-Λ shows promise of resembling the ΛCDM cosmology. We show that the vector field has the effect of a nonuniform dark fluid, which resembles dark matter in galaxies and dark energy in the late universe.

Citation

Halle, A., Zhao, H., & Li, B. (2008). A Nonuniform Dark Energy Fluid: Perturbation Equations. Astrophysical Journal Supplement, 177(1), 1-13. https://doi.org/10.1086/587744

• Journal Article Type: Article
• Publication Date: Jul 1, 2008
• Deposit Date: Jan 20, 2012
• Publicly Available Date: May 1, 2014
• Journal: Astrophysical Journal Supplement
• Print ISSN: 0067-0049
• Electronic ISSN: 1538-4365
• Publisher: American Astronomical Society
• Peer Reviewed: Peer Reviewed
• Volume: 177
• Issue: 1
• Pages: 1-13
• DOI: https://doi.org/10.1086/587744
• Keywords: Cosmology: theory, Dark matter, Gravitation.
• Public URL: https://durham-repository.worktribe.com/output/1499545