论文标题
通过$ n $ body模拟探索KSZ速度重建和Halo模型
Exploring KSZ velocity reconstruction with $N$-body simulations and the halo model
论文作者
论文摘要
KSZ速度重建是一种最近提出的方法，用于通过将二次估计器$ \ hat {v} _r $应用于小规模的CMB和Galaxy目录，用于绘制宇宙最大尺度模式。我们在$ n $ body模拟管道中实现KSZ速度重建并探索其属性。我们发现，重建噪声可能大于通常假定的分析预测。我们重新审视分析预测，并找到解释差异的其他噪声术语。新术语是从六点晕模型计算获得的，类似于$ n^{（1）} $和$ n^{（3/2）} $偏见。我们实施了一个MCMC管道，该管道从$ n $ body KSZ模拟中估算$ f_ {nl} $，并表明它恢复了$ f_ {nl} $的无偏估计，统计错误与Fisher Matrix预测一致。总体而言，这些结果证实，KSZ速度重建将在不久的将来是对宇宙学的有力探测，但是噪声功率谱中应包括新的术语。
KSZ velocity reconstruction is a recently proposed method for mapping the largest-scale modes of the universe, by applying a quadratic estimator $\hat{v}_r$ to the small-scale CMB and a galaxy catalog. We implement kSZ velocity reconstruction in an $N$-body simulation pipeline and explore its properties. We find that the reconstruction noise can be larger than the analytic prediction which is usually assumed. We revisit the analytic prediction and find additional noise terms which explain the discrepancy. The new terms are obtained from a six-point halo model calculation, and are analogous to the $N^{(1)}$ and $N^{(3/2)}$ biases in CMB lensing. We implement an MCMC pipeline which estimates $f_{NL}$ from $N$-body kSZ simulations, and show that it recovers unbiased estimates of $f_{NL}$, with statistical errors consistent with a Fisher matrix forecast. Overall, these results confirm that kSZ velocity reconstruction will be a powerful probe of cosmology in the near future, but new terms should be included in the noise power spectrum.
