Cosmological simulation in tides: power spectra, halo shape responses, and shape assembly bias
Cosmological simulation in tides: power spectra, halo shape responses, and shape assembly bias
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DOI：
10.1088/1475-7516/2021/04/041
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发表时间：
2020-11
影响因子：
6.4
通讯作者：
Kazuyuki Akitsu;Yin Li;T. Okumura
中科院分区：
文献类型：
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作者：
Kazuyuki Akitsu;Yin Li;T. Okumura
发展良好的分离宇宙技术使得能够精确校准任何可观测到的各向同性长波长密度波动的响应。大尺度环境也拥有潮汐模式，各向异性地扰动所有可观测量。在分离的宇宙中，无论是长潮汐和密度模式可以被一个有效的各向异性背景吸收，短模式的相互作用和演化相应地改变。我们进一步发展了潮汐模拟方法，包括适当的修正二阶拉格朗日摄动理论（2LPT），以产生模拟的初始条件。我们测量的线性潮汐响应的物质功率谱，在高红移从我们修改后的2LPT，并在低红移的潮汐模拟。我们的结果同意定性与以前的作品，但在这两种情况下表现出定量的差异。我们还测量了晕形状的线性潮汐响应，即形状偏差，并找到了它与线性晕偏差的普遍关系，给出了一个拟合公式。此外，类似于组装偏置，我们研究了形状偏置的二次依赖性，并首次发现了形状偏置对晕圈浓度和轴比的依赖性。我们的研究结果提供了有用的见解，研究的内在对齐作为污染或信息的来源。当我们使用星系形状的内在排列作为精确的宇宙学工具时，需要正确地考虑这些影响。
The well-developed separate universe technique enables accurate calibration of the response of any observable to an isotropic long-wavelength density fluctuation. The large-scale environment also hosts tidal modes that perturb all observables anisotropically. As in the separate universe, both the long tidal and density modes can be absorbed by an effective anisotropic background, on which the interaction and evolution of the short modes change accordingly. We further develop the tidal simulation method, including proper corrections to the second order Lagrangian perturbation theory (2LPT) to generate initial conditions of the simulations. We measure the linear tidal responses of the matter power spectrum, at high redshift from our modified 2LPT, and at low redshift from the tidal simulations. Our results agree qualitatively with previous works, but exhibit quantitative differences in both cases. We also measure the linear tidal response of the halo shapes, or the shape bias, and find its universal relation with the linear halo bias, for which we provide a fitting formula. Furthermore, analogous to the assembly bias, we study the secondary dependence of the shape bias, and discover for the first time the dependence on the halo concentration and axis ratio. Our results provide useful insights for studies of the intrinsic alignment as a source of either contamination or information. These effects need to be correctly taken into account when one uses intrinsic alignments of galaxy shapes as a precision cosmological tool.