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arXiv 1112.4752astro-ph.CO
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内禀排列模型选择对宇宙剪切的宇宙学影响

The Cosmological Impact of Intrinsic Alignment Model Choice for Cosmic Shear

Donnacha Kirk, Anais Rassat, Ole Host, Sarah Bridle

摘要:

我们考虑星系内禀排列对弱引力透镜暗能量约束的影响。在Hirata & Seljak(2010)的简要说明和Laszlo et al.(2011)的进一步解释之后,我们总结了IA线性排列模型的最新版本。我们显示宇宙学的偏见的暗能量状态方程参数w0和wa,如果IA被忽略会发生。我们发现,w0和wa都是灾难性的偏见,由一个绝对值,刚刚大于统一下的Fisher矩阵近似。这与早期IA实现的偏差大几倍形成对比。因此,毫无疑问,在今后的第三阶段试验和以后的试验中必须考虑到执行协定。我们使用了一个灵活的网格IA和星系偏置参数在以前的工作中使用,并调查会发生什么,如果宇宙使用最新的IA模型,但我们假设早期版本。我们发现,尽管两个IA模型之间的差异很大,网格的灵活性是足够的,以消除宇宙学的偏见,恢复正确的暗能量状态方程。在附录中,我们比较观察到的剪切功率谱,从以前流行的实施和解释的差异。

英文摘要:

We consider the effect of galaxy intrinsic alignments (IAs) on dark energy constraints from weak gravitational lensing. We summarise the latest version of the linear alignment model of IAs, following the brief note of Hirata & Seljak (2010) and further interpretation in Laszlo et al. (2011). We show the cosmological bias on the dark energy equation of state parameters w0 and wa that would occur if IAs were ignored. We find that w0 and wa are both catastrophically biased, by an absolute value of just greater than unity under the Fisher matrix approximation. This contrasts with a bias several times larger for the earlier IA implementation. Therefore there is no doubt that IAs must be taken into account for future Stage III experiments and beyond. We use a flexible grid of IA and galaxy bias parameters as used in previous work, and investigate what would happen if the universe used the latest IA model, but we assumed the earlier version. We find that despite the large difference between the two IA models, the grid flexibility is sufficient to remove cosmological bias and recover the correct dark energy equation of state. In an appendix, we compare observed shear power spectra to those from a popular previous implementation and explain the differences.

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