arXiv 0811.44952008-11gr-qcastro-ph

平均罗伯逊-沃克宇宙学

Averaging Robertson-Walker Cosmologies

Iain A. Brown, Georg Robbers, Juliane Behrend

备注：: 18 pages, 11 figures, ReVTeX. Updated to version accepted by JCAP
发表信息：: JCAP 0904:016,2009
DOI：: 10.1088/1475-7516/2009/04/016

摘要：

当人们直接对爱因斯坦方程求平均以恢复有效的罗伯逊-沃克宇宙学，而不是假设先验的背景时，宇宙学的逆反应就产生了。虽然通常在暗能量的背景下讨论，但严格地说，任何宇宙学模型都应该从这样的过程中恢复。我们适用于线性罗伯逊-沃克宇宙包含物质，辐射和暗能量的Buchert平均形式主义和数值评估之间的差异的假设和平均行为，发现最大的偏差爱因斯坦-德西特宇宙，迅速增加与哈勃率为0.01%的影响h=0.701。对于LCDM和谐模型，逆反应的量级为Ω_eff~ 4 × 10 ^-6，而对于暗能量模型，逆反应的量级在2倍或3倍之内。复合时的影响约为10^-8，而深辐射占优时的影响则渐近于一个恒定值。在Einstein-de Sitter模型、协调模型和quintessence模型中，反反应的有效状态方程一般都是尘埃状的，而在强幻影模型中，可以发现状态方程w_eff<-1/3的反反应。

英文摘要：

The cosmological backreaction arises when one directly averages the Einstein equations to recover an effective Robertson-Walker cosmology, rather than assuming a background a priori. While usually discussed in the context of dark energy, strictly speaking any cosmological model should be recovered from such a procedure. We apply the Buchert averaging formalism to linear Robertson-Walker universes containing matter, radiation and dark energy and evaluate numerically the discrepancies between the assumed and the averaged behaviour, finding the largest deviations for an Einstein-de Sitter universe, increasing rapidly with Hubble rate to a 0.01% effect for h=0.701. For the LCDM concordance model, the backreaction is of the order of Omega_eff~4x10^-6, with those for dark energy models being within a factor of two or three. The impacts at recombination are of the order of 10^-8 and those in deep radiation domination asymptote to a constant value. While the effective equations of state of the backreactions in Einstein-de Sitter, concordance and quintessence models are generally dust-like, a backreaction with an equation of state w_eff<-1/3 can be found for strongly phantom models.

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