Improved Methods for Estimating Peculiar Velocity Correlation Functions Using Volume Weighting
Improved Methods for Estimating Peculiar Velocity Correlation Functions Using Volume Weighting
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DOI：
10.3847/1538-4357/ac0e37
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发表时间：
2021-08
期刊：
影响因子：
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通讯作者：
Yuyu Wang;S. Peery;H. Feldman;R. Watkins
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作者：
Yuyu Wang;S. Peery;H. Feldman;R. Watkins
我们提出了一种改进的方法来计算平行和垂直速度相关函数直接从特殊的速度调查使用加权最大似然估计。新方法的一个核心特点是使用了一个位置相关的加权方案，减少了附近星系的影响，在大多数调查中，这些星系相对于更遥远的星系通常被过度代表。我们证明，以这种方式计算的相关函数是不太容易受到偏见，由于我们在宇宙中的特定位置，因此更容易与线性理论和调查之间。我们的研究结果表明，平行速度相关函数是一个很有前途的宇宙学探测，因为它提供了一个更好的近似高斯分布比其他速度相关函数，其偏差更容易通过加权最小化。虽然位置加权的平行速度相关函数增加了统计不确定性，但它降低了宇宙方差，并有望在未来与更精确的速度测量相结合，提供比其他相关方法更稳定和更严格的宇宙学参数约束。
We present an improved method for calculating the parallel and perpendicular velocity correlation functions directly from peculiar velocity surveys using weighted maximum-likelihood estimators. A central feature of the new method is the use of a position-dependent weighting scheme that reduces the influence of nearby galaxies, which are typically overrepresented relative to more distant galaxies in most surveys. We demonstrate that correlation functions calculated in this way are less susceptible to biases due to our particular location in the universe, and thus are more easily comparable to linear theory and between surveys. Our results suggest that the parallel velocity correlation function is a promising cosmological probe, given that it provides a better approximation of a Gaussian distribution than other velocity correlation functions and that its bias is more easily minimized by weighting. Though the position-weighted parallel velocity correlation function increases the statistical uncertainty, it decreases the cosmic variance and is expected to provide more stable and tighter cosmological parameter constraints than other correlation methods in conjunction with more precise velocity surveys in the future.