A New approach to the evolution of cosmological perturbations on large scales
By D. Wands, Karim A. Malik, D. Lyth, Andrew R. Liddle. 2000
791 citations recorded by the source corpus.
We discuss the evolution of linear perturbations about a Friedmann-Robertson-Walker background metric, using only the local conservation of energy-momentum. We show that on sufficiently large scales the curvature perturbation on spatial hypersurfaces of uniform-density is conserved when the non-adiabatic pressure perturbation is negligible. This is the first time that this result has been demonstrated independently of the gravitational field equations. A physical picture of long-wavelength perturbations as being composed of separate Robertson-Walker universes gives a simple understanding of the possible evolution of the curvature perturbation, in particular clarifying the conditions under which super-horizon curvature perturbations may vary.
Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics
View Paper: https://www.semanticscholar.org/paper/f8d8f232f930c5f7c858fd02125ad3cc4b2647c0
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In Nuclear and High Energy Physics
Citations in the corpus
- Non-linear isocurvature perturbations and non-Gaussianities (2008, positive): “Our results for the primordial curvature perturbation are consistent with the non-linear δN -formalism [4], derived in the large scale limit where the separate universes approach [45] is used to evaluate the perturbed expansion using the homogeneous background solutions.”
- Gravitational waves from a universe filled with primordial black holes (2020, background): “On super-Hubble scales, ζr and ζPBH are separately conserved [44], as is the isocurvature perturbation defined by S = 3 (ζPBH − ζr) .”
- Correlation functions in stochastic inflation (2015, methodology): “Thus we can use the homogeneous FLRW solutions to describe the local evolution, which is known as the “quasiisotropic” [55–58] or “separate universe” approach [51,59, 60].”
- Introduction to Loop Quantum Cosmology (2011, background): “As a side remark, the patches of volume L3 find a most natural classical analogue in inhomogeneous cosmologies, in particular within the separate universe picture [198].”
- Inflation, Cosmic Perturbations and Non-Gaussianities (2013, neutral): “Thus we can define the non-adiabatic part of p(ρ, si) as [167] δpnad ≡ ∂p ∂si ( δsi − ṡi ρ̇ δρ ) + · · · = δp− ṗ0 ρ̇0 δρ .”