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arXiv 1106.0834astro-ph.COgr-qchep-phhep-th
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非线性暗能量聚类

Non-linear dark energy clustering

Stefano Anselmi, Guillermo Ballesteros, Massimo Pietroni

摘要:

考虑具有任意声速和状态方程的暗能量流体,在非线性水平上讨论其成团效应对冷暗物质分布的影响。我们写的连续性,欧拉和泊松方程的系统在牛顿近似。然后,利用时间重整化群方法计算了各阶微扰修正,计算了总的团簇功率谱和物质功率谱。在线性水平上,暗能量的声速不同于光的声速,这会改变观测上感兴趣的尺度上的功率谱,比如那些与重子声波振荡相关的尺度。我们发现,改变暗能量的声速对物质功率谱的非线性修正的影响低于百分之一的水平,因此,这些修正可以很好地模拟他们的对应物在宇宙学的情况下,光滑的暗能量。我们还表明,物质增长指数的非线性效应可以高达10- 15%的小尺度。

英文摘要:

We consider a dark energy fluid with arbitrary sound speed and equation of state and discuss the effect of its clustering on the cold dark matter distribution at the non-linear level. We write the continuity, Euler and Poisson equations for the system in the Newtonian approximation. Then, using the time renormalization group method to resum perturbative corrections at all orders, we compute the total clustering power spectrum and matter power spectrum. At the linear level, a sound speed of dark energy different from that of light modifies the power spectrum on observationally interesting scales, such as those relevant for baryonic acoustic oscillations. We show that the effect of varying the sound speed of dark energy on the non-linear corrections to the matter power spectrum is below the per cent level, and therefore these corrections can be well modelled by their counterpart in cosmological scenarios with smooth dark energy. We also show that the non-linear effects on the matter growth index can be as large as 10-15 per cent for small scales.

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