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f（R）宇宙学II的非线性演化：功率谱

Non-linear evolution of f(R) cosmologies II: power spectrum

Hiroaki Oyaizu, Marcos Lima, Wayne Hu

备注：
9 pages, 6 figures
发表信息：
Phys.Rev.D78:123524,2008
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摘要：

我们进行了一套宇宙学模拟的修改后的作用量f（R）模型，宇宙加速产生的重力，而不是暗能量的变化。这些模型引入了额外的标量自由度，其增强了标量的倒数质量或康普顿标度以下的重力。模拟显示了所谓的变色龙机制，这是满足引力局部约束所必需的，这种尺度取决于环境，特别是局部引力势的深度。我们发现，变色龙机制可以实质上抑制功率谱的增强在非线性制度，如果背景场值是相当或小于典型结构的引力势的深度。尽管如此，在中等尺度的功率谱增强仍然在一个可测量的水平模型，即使膨胀的历史是无法区分的宇宙学常数，冷暗物质模型。简单的标度关系，把线性功率谱到一个非线性谱不能捕捉到的修改f（R）由于在塌陷结构的变化，变色龙机制，和时间演变的修改。

英文摘要：

We carry out a suite of cosmological simulations of modified action f(R) models where cosmic acceleration arises from an alteration of gravity instead of dark energy. These models introduce an extra scalar degree of freedom which enhances the force of gravity below the inverse mass or Compton scale of the scalar. The simulations exhibit the so-called chameleon mechanism, necessary for satisfying local constraints on gravity, where this scale depends on environment, in particular the depth of the local gravitational potential. We find that the chameleon mechanism can substantially suppress the enhancement of power spectrum in the non-linear regime if the background field value is comparable to or smaller than the depth of the gravitational potentials of typical structures. Nonetheless power spectrum enhancements at intermediate scales remain at a measurable level for models even when the expansion history is indistinguishable from a cosmological constant, cold dark matter model. Simple scaling relations that take the linear power spectrum into a non-linear spectrum fail to capture the modifications of f(R) due to the change in collapsed structures, the chameleon mechanism, and the time evolution of the modifications.

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