论文标题

潮汐中的宇宙学模拟:功率谱和光环形状响应,形状组装偏差

Cosmological simulation in tides: power spectra and halo shape responses, and shape assembly bias

论文作者

Akitsu, Kazuyuki, Li, Yin, Okumura, Teppei

论文摘要

发达的单独宇宙技术可以准确校准对各向同性长波长密度波动的任何可观察到的响应。大规模环境还设有潮汐模式,这些模式在所有观察到各向异性上都扰乱了所有观察。就像在单独的宇宙中一样,长潮汐和密度模式都可以通过有效的各向异性背景来吸收,在这种背景下,短模式的相互作用和演变会相应地改变。我们进一步开发了潮汐模拟方法,包括对二阶拉格朗日扰动理论(2LPT)的适当校正,以生成模拟的初始条件。我们测量了物质功率谱的线性潮汐响应,从我们的改装2LPT的高红移和潮汐模拟的低红移。我们的结果与以前的作品定性一致,但在两种情况下都表现出定量差异。我们还测量了光环形状或形状偏置的线性潮汐响应,并找到了其与线性光环偏置的通用关系,为此我们提供了拟合公式。此外,类似于组装偏差,我们研究了形状偏差的次要依赖性,并首次发现对光晕浓度和轴比的依赖性。我们的结果为研究内在对齐的研究提供了有用的见解,作为污染或信息的来源。当人们将星系形状的固有比对作为精确的宇宙学工具时,需要正确考虑这些效果。

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 dependence on halo concentration and axis ratio. Our results provide useful insights for studies of the intrinsic alignment as 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.

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