Testing the impact of satellite anisotropy on large- and small-scale intrinsic alignments using hydrodynamical simulations
Testing the impact of satellite anisotropy on large- and small-scale intrinsic alignments using hydrodynamical simulations
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DOI：
10.1093/mnras/stz3114
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发表时间：
2019-01
影响因子：
4.8
通讯作者：
S. Samuroff;R. Mandelbaum;T. Di Matteo-T.-Di Matteo-1392893525
中科院分区：
文献类型：
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作者：
S. Samuroff;R. Mandelbaum;T. Di Matteo-T.-Di Matteo-1392893525
星系内禀排列（IA）长期以来一直被认为是一个重要的污染物，弱透镜为基础的宇宙学推断。在本文中，我们试图量化的影响，一个共同的建模假设在分析描述的IA：球对称的暗物质晕。了解这种影响是很重要的，因为目前这一代的IA模型是有限的，特别是在小尺度上，建立一个准确的理论描述将是必不可少的充分利用未来的透镜数据的信息。我们的分析是基于113560星系目录之间的z = 0.06和1.00从Bullveblack-ii，一个流体动力学模拟的盒长度为100\，h^{-1}$ Mpc。我们发现卫星各向异性的贡献水平为$30！40{\rm %}}$的小规模对齐相关函数。在分离大于$1 \，h^{-1}$ Mpc的影响是大致规模独立的，诱导的IA功率谱的振幅的移位$\sim 20{{\rm %}}$。这些结论在整个红移范围内，以及在illustris模拟和tubeblack-ii模拟之间是一致的。宇宙学的影响，这些结果进行了测试，使用模拟的似然分析。合成宇宙剪切数据与未来LSST调查的预期特征（深度，面积和数量密度）一起构建。我们的研究结果表明，使用基于球对称的晕模型来模拟对准可能会导致S8和w的宇宙学参数偏差达到1.5σ水平。
Galaxy intrinsic alignments (IAs) have long been recognized as a significant contaminant to weak lensing-based cosmological inference. In this paper we seek to quantify the impact of a common modelling assumption in analytic descriptions of IAs: that of spherically symmetric dark matter haloes. Understanding such effects is important as the current generation of IA models are known to be limited, particularly on small scales, and building an accurate theoretical description will be essential for fully exploiting the information in future lensing data. Our analysis is based on a catalogue of 113 560 galaxies between z = 0.06 and 1.00 from massiveblack-ii, a hydrodynamical simulation of box length $100 \, h^{-1}$ Mpc. We find satellite anisotropy contributes at the level of $\ge 30\!-\!40{{\ \rm per\ cent}}$ to the small-scale alignment correlation functions. At separations larger than $1 \, h^{-1}$ Mpc the impact is roughly scale independent, inducing a shift in the amplitude of the IA power spectra of $\sim 20{{\ \rm per\ cent}}$. These conclusions are consistent across the redshift range and between the massiveblack-ii and the illustris simulations. The cosmological implications of these results are tested using a simulated likelihood analysis. Synthetic cosmic shear data are constructed with the expected characteristics (depth, area, and number density) of a future LSST-like survey. Our results suggest that modelling alignments using a halo model based upon spherical symmetry could potentially induce cosmological parameter biases at the ∼1.5σ level for S8 and w.