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arXiv 0910.3786astro-ph.CO
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精密宇宙学的弱透镜功率谱:多重偏转、约化剪切和透镜偏置修正

Weak lensing power spectra for precision cosmology: Multiple-deflection, reduced shear and lensing bias corrections

Elisabeth Krause, Christopher M. Hirata

摘要:

通常认为,在弱透镜观测中测得的椭率功率谱可以表示为对下伏物质功率谱的积分。这在二阶引力势中是正确的。我们扩展了标准的计算,构造了引力势的四阶修正。有四种类型的修正:由于多重偏转引起的透镜剪切修正;由于形状畸变探测约化剪切$γ/(1-κ)$而不是剪切本身引起的修正;与约化剪切到平均椭圆率的非线性转换有关的修正;和修正,由于事实上,观测星系的选择和剪切测量是基于星系的亮度和大小,de)通过透镜放大。我们展示了如何先前考虑的剪切功率谱的修正对应于我们的分析中的条款,并突出显示以前没有确定的新条款。所有的校正项明确给出的积分的物质功率谱,双谱,和三谱,并在z=1的源的情况下进行数值计算。我们发现协议与以前的作品的${\mathcal O}(Φ^3)$条款。我们发现,对于雄心勃勃的未来调查,${\mathcal O}(Φ^4)$条款影响功率谱在~ 1-5 $σ$水平,因此,他们将需要考虑,但不太可能代表一个严重的困难,弱透镜作为宇宙学探测。

英文摘要:

It is usually assumed that the ellipticity power spectrum measured in weak lensing observations can be expressed as an integral over the underlying matter power spectrum. This is true at second order in the gravitational potential. We extend the standard calculation, constructing all corrections to fourth order in the gravitational potential. There are four types of corrections: corrections to the lensing shear due to multiple-deflections; corrections due to the fact that shape distortions probe the reduced shear $γ/(1-κ)$ rather than the shear itself; corrections associated with the non-linear conversion of reduced shear to mean ellipticity; and corrections due to the fact that observational galaxy selection and shear measurement is based on galaxy brightnesses and sizes which have been (de)magnified by lensing. We show how the previously considered corrections to the shear power spectrum correspond to terms in our analysis, and highlight new terms that were not previously identified. All correction terms are given explicitly as integrals over the matter power spectrum, bispectrum, and trispectrum, and are numerically evaluated for the case of sources at z=1. We find agreement with previous works for the ${\mathcal O}(Φ^3)$ terms. We find that for ambitious future surveys, the ${\mathcal O}(Φ^4)$ terms affect the power spectrum at the ~ 1-5 $σ$ level; they will thus need to be accounted for, but are unlikely to represent a serious difficulty for weak lensing as a cosmological probe.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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