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arXiv 2106.07641astro-ph.CO
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ShapeFit:在BAO和RSD以外的星系巡天中提取功率谱形状信息

ShapeFit: extracting the power spectrum shape information in galaxy surveys beyond BAO and RSD

Samuel Brieden, Héctor Gil-Marín, Licia Verde

摘要:

在标准(经典)的方法中,从光谱调查中得到的星系团测量被压缩成重子声学振荡和红移空间畸变测量,这反过来又可以与宇宙学模型进行比较。最近的工作表明,避免这一中间步骤,直接拟合全功率谱信号(全建模)导致宇宙学参数更严格的约束。在这里,我们展示了这些额外信息的来源,并通过一个额外的有效参数扩展了经典方法,这样它就可以有效地捕获与完整建模方法相同的信息量,但以独立于模型的方式。我们验证这种新方法(ShapeFit)模拟目录,并比较其性能的完整建模方法,找到两者提供等效的结果。经典方法的ShapeFit扩展在信息内容方面促进了完全建模水平的标准分析,其优点是:i)更加独立于模型; ii)提供对额外宇宙学信息起源的理解; iii)允许对观测系统学的影响进行鲁棒控制。

英文摘要:

In the standard (classic) approach, galaxy clustering measurements from spectroscopic surveys are compressed into baryon acoustic oscillations and redshift space distortions measurements, which in turn can be compared to cosmological models. Recent works have shown that avoiding this intermediate step and fitting directly the full power spectrum signal (full modelling) leads to much tighter constraints on cosmological parameters. Here we show where this extra information is coming from and extend the classic approach with one additional effective parameter, such that it captures, effectively, the same amount of information as the full modelling approach, but in a model-independent way. We validate this new method (ShapeFit) on mock catalogs, and compare its performance to the full modelling approach finding both to deliver equivalent results. The ShapeFit extension of the classic approach promotes the standard analyses at the level of full modelling ones in terms of information content, with the advantages of i) being more model independent; ii) offering an understanding of the origin of the extra cosmological information; iii) allowing a robust control on the impact of observational systematics.

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