Limits on statistical anisotropy from BOSS DR12 galaxies using bipolar spherical harmonics
Limits on statistical anisotropy from BOSS DR12 galaxies using bipolar spherical harmonics
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DOI：
10.1093/mnras/stx2333
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发表时间：
2017-04
影响因子：
4.8
通讯作者：
Naonori S. Sugiyama;M. Shiraishi;T. Okumura
中科院分区：
文献类型：
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作者：
Naonori S. Sugiyama;M. Shiraishi;T. Okumura
利用双极球面谐波（BipoSHs）在傅里叶空间和位形空间测量三维星系团中的统计各向异性特征。然后，我们在原始功率谱中约束一个众所周知的四极性各向异性参数$g_{2M}$，参数化为$P(\vec{k}) = \bar{P}(k) [ 1 + \sum_{M} g_{2M} Y_{2M}(\hat{k}) ]$，其中$M$决定各向异性的方向。这种各向异性信号由于测量几何形状的特殊性，容易受到人为不对称性的影响。我们精确地估计污染信号，并最终从数据中减去它。利用重子振荡光谱调查数据第12版获得的星系样本，我们没有发现违反统计各向同性的证据，$g_{2M}$在$2\sigma$水平内所有$M$都为零。$g_{2M}$型各向异性可以源于涉及方向相关调制$g_* (\hat{k} \cdot \hat{p})^2$的原始曲率功率谱。当$\hat{p}$被边缘化时，$g_{2M}$的边界被转换成$g_*$为$-0.09 < g_* < 0.08$，置信水平为$95\%$。
We measure statistically anisotropic signatures imprinted in three-dimensional galaxy clustering using bipolar spherical harmonics (BipoSHs) in both Fourier space and configuration space. We then constrain a well-known quadrupolar anisotropy parameter $g_{2M}$ in the primordial power spectrum, parametrized by $P(\vec{k}) = \bar{P}(k) [ 1 + \sum_{M} g_{2M} Y_{2M}(\hat{k}) ]$, with $M$ determining the direction of the anisotropy. Such an anisotropic signal is easily contaminated by artificial asymmetries due to specific survey geometry. We precisely estimate the contaminated signal and finally subtract it from the data. Using the galaxy samples obtained by the Baryon Oscillation Spectroscopic Survey Data Release 12, we find no evidence for violation of statistical isotropy, $g_{2M}$ for all $M$ to be of zero within the $2\sigma$ level. The $g_{2M}$-type anisotropy can originate from the primordial curvature power spectrum involving a directional-dependent modulation $g_* (\hat{k} \cdot \hat{p})^2$. The bound on $g_{2M}$ is translated into $g_*$ as $-0.09 < g_* < 0.08$ with a $95\%$ confidence level when $\hat{p}$ is marginalized over.