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arXiv 0704.2783astro-ph
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重子声学振荡的非线性演化

Nonlinear Evolution of Baryon Acoustic Oscillations

M. Crocce, R. Scoccimarro

摘要:

利用重正化微扰理论研究了暗物质功率谱和关联函数中重子声学振荡(BAO)的非线性演化。在以前的论文中,我们表明,RPT成功地预测声振荡的阻尼,在这里,我们扩展我们的计算,以增强功率由于模式耦合。我们表明,模式耦合产生额外的振荡,是与那些在线性光谱的相位,导致位移的尺度振荡节点定义相对于一个平滑的频谱。当进行傅立叶变换时,这些异相振荡在两点关联函数的声学峰值中引起双能级偏移。我们目前的预测,这些位移作为一个函数的红移,这些应被视为一个强大的下限,更现实的情况下,其中包括另外的红移失真和星系的偏见。我们表明,这些非线性效应发生在非常大的尺度,导致崩溃的线性理论在尺度远大于通常认为的。我们讨论了为什么维里化晕轮廓不负责这些影响,这可以从引力不稳定性的基本物理学理解。我们的研究结果与数值模拟结果非常吻合,可以作为在未来观测中建模BAO的起点。为了达到这个目的,我们提出了一个简单的物理动机模型来纠正模式耦合引起的位移。

英文摘要:

We study the nonlinear evolution of the baryon acoustic oscillations (BAO) in the dark matter power spectrum and correlation function using renormalized perturbation theory (RPT). In a previous paper we showed that RPT successfully predicts the damping of acoustic oscillations; here we extend our calculation to the enhancement of power due to mode-coupling. We show that mode-coupling generates additional oscillations that are out of phase with those in the linear spectrum, leading to shifts in the scales of oscillation nodes defined with respect to a smooth spectrum. When Fourier transformed, these out of phase oscillations induce percent-level shifts in the acoustic peak of the two-point correlation function. We present predictions for these shifts as a function of redshift; these should be considered as a robust lower limit to the more realistic case that includes in addition redshift distortions and galaxy bias. We show that these nonlinear effects occur at very large scales, leading to a breakdown of linear theory at scales much larger than commonly thought. We discuss why virialized halo profiles are not responsible for these effects, which can be understood from basic physics of gravitational instability. Our results are in excellent agreement with numerical simulations, and can be used as a starting point for modeling BAO in future observations. To meet this end, we suggest a simple physically motivated model to correct for the shifts caused by mode-coupling.

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