Large scale curvature and entropy perturbations for multiple interacting fluids
Large scale curvature and entropy perturbations for multiple interacting fluids
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DOI：
10.1103/physrevd.67.063516
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发表时间：
2002-11
影响因子：
5
通讯作者：
Karim A. Malik;D. Wands;Carlo Ungarelli Institut d'Astrophysique de Paris;Portsmouth;Birmingham
中科院分区：
文献类型：
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作者：
Karim A. Malik;D. Wands;Carlo Ungarelli Institut d'Astrophysique de Paris;Portsmouth;Birmingham
We present a gauge-invariant formalism to study the evolution of curvature perturbations in a Friedmann-Robertson-Walker universe filled by multiple interacting fluids. We resolve arbitrary perturbations into adiabatic and entropy components and derive their coupled evolution equations. We demonstrate that perturbations obeying a generalized adiabatic condition remain adiabatic in the large-scale limit, even when one includes energy transfer between fluids. As a specific application we study the recently proposed curvaton model, in which the curvaton decays into radiation. We use the coupled evolution equations to show how an initial isocurvature perturbation in the curvaton gives rise to an adiabatic curvature perturbation after the curvaton decays
