Non-linear curvature inhomogeneities and backreaction for relativistic viscous fluids

Abstract

The non-perturbative curvature inhomogeneities induced by relativistic viscous fluids are not conserved in the large-scale limit. However when the bulk viscosity is a function of the total energy density of the plasma (or of the trace of the extrinsic curvature) the relevant evolution equations develop a further symmetry preventing the non-linear growth of curvature perturbations. In this situation the fully inhomogeneous evolution can be solved to leading order in the gradient expansion. Over large-scales both the acceleration and the curvature inhomogeneities are determined by the bulk viscosity coefficients. Conversely the shear viscosity does not affect the evolution of the curvature and does not produce any acceleration. The curvature modes analyzed here do not depend on the choice of time hypersurfaces and are invariant for infinitesimal coordinate transformations in the perturbative regime.

25 pages, no figures; corrected typos to match the published version

References in corpus (11)

• Wilkinson Microwave Anisotropy Probe (WMAP) Three Year Results: Implications for Cosmology
• Three Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Polarization Analysis
• Multiplicity scaling in ideal and viscous hydrodynamics
• Dissipative relativistic fluid dynamics: a new way to derive the equations of motion from kinetic theory
• Does Bulk Viscosity Create a Viable Unified Dark Matter Model?
• Correlated adiabatic and isocurvature CMB fluctuations in the wake of the WMAP
• Entropy perturbations and large-scale magnetic fields
• Constraints on scalar and tensor perturbations in phenomenological and two-field inflation models: Bayesian evidences for primordial isocurvature and tensor modes
• No-hair conjectures, primordial shear and protoinflationary initial conditions
• Uniform gradient expansions
• Viscous modes, isocurvature perturbations and CMB initial conditions

Cited by in corpus (3)

• Assessing the impact of bulk and shear viscosities on large scale structure formation
• Quasiadiabatic modes from viscous inhomogeneities
• Note on bulk viscosity as an alternative to dark energy