Construction of cosmologically viable f(G) dark energy models
Construction of cosmologically viable f(G) dark energy models
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DOI：
10.1016/j.physletb.2009.03.060
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发表时间：
2008-10
影响因子：
4.4
通讯作者：
A. D. Felice;S. Tsujikawa
中科院分区：
文献类型：
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作者：
A. D. Felice;S. Tsujikawa
我们推导出的条件下，f（G）的引力模型，其拉格朗日密度f的书面条款的高斯-邦纳项G，是宇宙学上可行的。最关键的条件是d2 f/dG 2>0，这是确保后期de Sitter解的稳定性以及标准辐射/物质主导时期的存在所必需的。我们提出了一些明确的f（G）模型，其中宇宙加速是由物质时代。我们发现，暗能量的状态方程可以在到达现在的宇宙之前穿过幻影鸿沟。可行模型具有渐近行为d2 f/dG 2 →+0，|G| →∞，在这种情况下，发生扰动的快速振荡，除非这种振荡自由度相对于早期宇宙中的均匀模式被抑制。我们还介绍了一种迭代方法，以避免与大质量的振荡模式的数值不稳定性。
We derive conditions under which f(G) gravity models, whose Lagrangian densities f are written in terms of a Gauss–Bonnet term G, are cosmologically viable. The most crucial condition to be satisfied is d2f/dG2>0, which is required to ensure the stability of a late-time de Sitter solution as well as the existence of standard radiation/matter dominated epochs. We present a number of explicit f(G) models in which a cosmic acceleration is followed by the matter era. We find that the equation of state of dark energy can cross the phantom divide before reaching the present Universe. The viable models have asymptotic behavior d2f/dG2→+0 for |G|→∞, in which case a rapid oscillation of perturbations occurs unless such an oscillating degree of freedom is suppressed relative to a homogeneous mode in the early universe. We also introduce an iterative method to avoid numerical instabilities associated with a large mass of the oscillating mode.