Large-scale cosmological perturbations on tbe brane

D. Langlois, R. Maartens, M. Sasaki, D. Wands

Research output: Contribution to journalArticlepeer-review


In brane-world cosmologies of Randall-Sundrum type, we show that the evolution of large-scale curvature perturbations may be determined on the brane, without solving the bulk perturbation equations. The influence of the bulk gravitational field on the brane is felt through a projected Weyl tensor which behaves effectively like an imperfect radiation fluid with anisotropic stress. We define curvature perturbations on uniform density surfaces for both the matter and Weyl fluids, and show that their evolution on large scales follows directly from the energy conservation equations for each fluid. The total curvature perturbation is not necessarily constant for adiabatic matter perturbations, but can change due to the Weyl entropy perturbation. To relate this curvature perturbation to the longitudinal gauge metric potentials requires knowledge of the Weyl anisotropic stress which is not determined by the equations on the brane. We discuss the implications for large-angle anisotropies on the cosmic microwave background sky.
Original languageEnglish
Article number084009
Pages (from-to)084009
JournalPhysical Review D
Issue number8
Early online date16 Mar 2001
Publication statusPublished - 15 Apr 2001


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