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arXiv 1306.1533astro-ph.CO
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LyMAS:从暗物质密度场预测大尺度莱曼α森林统计

LyMAS: Predicting Large-Scale Lyman-alpha Forest Statistics from the Dark Matter Density Field

Sébastien Peirani, David H. Weinberg, Stéphane Colombi, Jérémy Blaizot, Yohan Dubois, Christophe Pichon

摘要:

我们描述了LyMAS(Ly-alpha质量关联方案),这是一种从暗物质分布的中等分辨率模拟中预测大尺度Ly-alpha森林中聚类统计的方法,并从较小体积的高分辨率流体动力学模拟中进行校准。我们使用自适应网格流体动力学程序RAMSES生成的50 Mpc/h的同动体积“Horizon MareNostrum”模拟来计算条件概率分布P(Fs| δ_s)的透射通量F_s,在光谱分辨率尺度上平滑(1维),在暗物质密度对比度δ_s上,在类似的尺度上平滑(3维)。在这项研究中,我们采用的光谱分辨率的SDSS-III BOSS在z=2.5,我们发现最佳的结果为暗物质平滑长度σ =0.3兆秒差距/小时(共动)。在扩展的形式,LyMAS准确地再现了一维功率谱和1点流量分布的水力模拟谱。应用于MareNostrum暗物质领域,LyMAS准确地预测了2点条件通量分布和通量关联函数的全水力模拟的横向视线分离小至1兆秒差距/小时,包括红移空间失真的影响。它比确定性密度通量映射(“波动冈恩-彼得森近似”)更准确,通常用于森林的大体积模拟。通过MareNostrum校准,我们将LyMAS应用于300 Mpc/h和1.0 Gpc/h立方体的1024^3 N体模拟,以产生大型的公开可用的模拟BOSS光谱目录,这些光谱探测了大的共动体积。LyMAS将成为解释3-D Ly-alpha森林数据的强大工具,从而将BOSS和其他大规模类星体吸收调查的测量转化为对暗能量,暗物质,空间几何和IGM物理的约束。

英文摘要:

[abridged] We describe LyMAS (Ly-alpha Mass Association Scheme), a method of predicting clustering statistics in the Ly-alpha forest on large scales from moderate resolution simulations of the dark matter distribution, with calibration from high-resolution hydrodynamic simulations of smaller volumes. We use the "Horizon MareNostrum" simulation, a 50 Mpc/h comoving volume evolved with the adaptive mesh hydrodynamic code RAMSES, to compute the conditional probability distribution P(F_s|delta_s) of the transmitted flux F_s, smoothed (1-dimensionally) over the spectral resolution scale, on the dark matter density contrast delta_s, smoothed (3-dimensionally) over a similar scale. In this study we adopt the spectral resolution of the SDSS-III BOSS at z=2.5, and we find optimal results for a dark matter smoothing length sigma=0.3 Mpc/h (comoving). In extended form, LyMAS exactly reproduces both the 1-dimensional power spectrum and 1-point flux distribution of the hydro simulation spectra. Applied to the MareNostrum dark matter field, LyMAS accurately predicts the 2-point conditional flux distribution and flux correlation function of the full hydro simulation for transverse sightline separations as small as 1 Mpc/h, including redshift-space distortion effects. It is substantially more accurate than a deterministic density-flux mapping ("Fluctuating Gunn-Peterson Approximation"), often used for large volume simulations of the forest. With the MareNostrum calibration, we apply LyMAS to 1024^3 N-body simulations of a 300 Mpc/h and 1.0 Gpc/h cube to produce large, publicly available catalogs of mock BOSS spectra that probe a large comoving volume. LyMAS will be a powerful tool for interpreting 3-d Ly-alpha forest data, thereby transforming measurements from BOSS and other massive quasar absorption surveys into constraints on dark energy, dark matter, space geometry, and IGM physics.

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