Cosmological anisotropy from non-comoving dark matter and dark energy

Abstract

We consider a cosmological model in which the two major fluid components of the Universe, dark energy and dark matter, flow with distinct four-velocities. This cosmological configuration is equivalent to a single anisotropic fluid, expanding with a four-velocity that is an appropriate combination of the two fluid four-velocities. The energy density of the single cosmological fluid is larger than the sum of the energy densities of the two perfect fluids, i.e., dark energy and dark matter, respectively, and contains a correction term due to the anisotropy generated by the differences in the four-velocities. Furthermore, the gravitational field equations of the two-fluid anisotropic cosmological model are obtained for a Bianchi type I geometry. By assuming that the non-comoving motion of the dark energy and dark matter induces small perturbations in the homogeneous and isotropic Friedmann-Lemaitre-Robertson-Walker type cosmological background, and that the anisotropy parameter is small, the equations of the cosmological perturbations due to the non-comoving nature of the two major components are obtained. The time evolution of the metric perturbations is explicitly obtained for the cases of the exponential and power law background cosmological expansion. Therefore, if there is a slight difference between the four-velocities of the dark energy and dark matter, the Universe would acquire some anisotropic characteristics, and its geometry will deviate from the standard FLRW one. In fact, the recent Planck results show that the presence of an intrinsic large scale anisotropy in the Universe cannot be excluded {\it a priori}, so that the model presented in this work can be considered as a plausible and viable working hypothesis.

16 pages, no figures; minor modifications; accepted for publication in JCAP

References in corpus (17)

• Unified cosmic history in modified gravity: from F(R) theory to Lorentz non-invariant models
• Planck 2013 results. I. Overview of products and scientific results
• Extra force in $f(R)$ modified theories of gravity
• Extended Theories of Gravity and their Cosmological and Astrophysical Applications
• Low surface brightness galaxies rotation curves in the low energy limit of $R^n$ gravity : no need for dark matter?
• Dark energy and dark matter as curvature effects
• Dark matter as a geometric effect in f(R) gravity
• Analysis of Rotation Curves in the framework of R^n gravity
• Generalized virial theorem in f(R) gravity
• Imprints of anisotropic inflation on the cosmic microwave background
• Dark matter and dark energy as a effects of Modified Gravity
• Probing Dark Energy Anisotropy
• Cosmology with moving dark energy and the CMB quadrupole
• On the Possibility of Anisotropic Curvature in Cosmology
• Two-fluid dark matter models
• Inflation and primordial power spectra at anisotropic spacetime inspired by Planck's constraints on isotropy of CMB
• Dark energy in motion

Cited by in corpus (15)

• Arbitrary scalar field and quintessence cosmological models
• On structure formation from a small-scales-interacting dark sector
• Anisotropic expansion and SNIa: an open issue
• The Einstein dark energy model
• Velocity-dependent interacting dark energy and dark matter with a Lagrangian description of perfect fluids
• Non-comoving Cosmology
• Vector dark energy models with quadratic terms in the Maxwell tensor derivatives
• Cosmological implications of the Weyl geometric gravity theory
• Warm inflation with non-comoving scalar field and radiation fluid
• Large-scale structure in superfluid Chaplygin gas cosmology
• Backreaction mechanism in multifluid and extended cosmologies
• Stability analysis of (a class of) anisotropic spacetimes
• Measuring our peculiar velocity from spectroscopic redshift surveys
• Horndeski in motion
• Effective models of non-singular quantum black holes