Generalised perturbation equations in bouncing cosmologies

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dc.creatorCardoso, Antonio
dc.creatorWands, David
dc.date2008-01-10
dc.date2008-07-14
dc.date.accessioned2026-07-07T11:55:09Z
dc.date.available2026-07-07T11:55:09Z
dc.descriptionWe consider linear perturbation equations for long-wavelength scalar metric perturbations in generalised gravity, applicable to non-singular cosmological models including a bounce from collapse to expansion in the very early universe. We present the general form for the perturbation equations which follows from requiring that the inhomogeneous universe on large scales obeys the same local equations as the homogeneous Friedmann-Robertson-Walker background cosmology (the separate universes approach). In a pseudo-longitudinal gauge this becomes a homogeneous second-order differential equation for adiabatic perturbations, which reduces to the usual equation for the longitudinal gauge metric perturbation in general relativity with vanishing anisotropic stress. As an application we show that the scale-invariant spectrum of perturbations in the longitudinal gauge generated during an ekpyrotic collapse are not transferred to the growing mode of adiabatic density perturbations in the expanding phase in a simple bounce model.
dc.description8 pages, no figures. Version to appear in PRD
dc.identifierhttps://arxiv.org/abs/0801.1667
dc.identifierhttp://arxiv.org/abs/0801.1667
dc.identifierPhys.Rev.D77:123538,2008
dc.identifierdoi:10.1103/PhysRevD.77.123538
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/205151
dc.subjectHigh Energy Physics - Theory
dc.subjectAstrophysics
dc.subjectGeneral Relativity and Quantum Cosmology
dc.titleGeneralised perturbation equations in bouncing cosmologies
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