A Nonuniform Dark Energy Fluid: Perturbation Equations

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

doi:10.1086/587744

A Nonuniform Dark Energy Fluid: Perturbation Equations

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

Authors

A. Halle

H. Zhao

Professor Baojiu Li baojiu.li@durham.ac.uk
Professor

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.