arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2108.01670astro-ph.COastro-ph.GAgr-qchep-exhep-ph
收藏

用BOSS CMASS样本首次检测Galerkin的连通四点关联函数

A First Detection of the Connected 4-Point Correlation Function of Galaxies Using the BOSS CMASS Sample

Oliver H. E. Philcox, Jiamin Hou, Zachary Slepian

摘要:

我们提出了一个$8.1σ$检测的非高斯四点关联函数(4PCF)使用的样本$N_{\rm g} \approx 8\times 10^5$星系从BOSS CMASS数据集。我们的测量使用Philcox等人(2021)的$\mathcal{O}(N_{\rm g}^2)$ NPCF估计器,包括在估计器水平减去断开的4PCF贡献(由两个2 PCF的乘积产生)的新修改。这种方法与以前的工作不同,并确保我们的信号是对引力引起的非高斯性的鲁棒检测。通过一组对数正态模拟验证了估计量的有效性,并讨论了不连通贡献的解析形式。由于4PCF的高维性,需要数据压缩;我们使用从理论协方差矩阵校准的基于信噪比的方案来限制$\sim$ $100$基向量。压缩对检测意义的影响最小,并且使用一套模拟目录促进传统的$χ^2$样分析。的显着性是稳定的,相对于不同的处理噪声的样本协方差(所产生的有限数量的模拟),但降低到$4.7σ$时,最小的星系分离$14 h^{-1}\mathrm{Mpc}$是强制执行的4PCF四面体(这样的统计可以更容易地建模)。在准线性制度的4PCF的可探测性意味着它将成为一个有用的工具,在约束宇宙学和星系的形成参数从即将到来的光谱调查。

英文摘要:

We present an $8.1σ$ detection of the non-Gaussian 4-Point Correlation Function (4PCF) using a sample of $N_{\rm g} \approx 8\times 10^5$ galaxies from the BOSS CMASS dataset. Our measurement uses the $\mathcal{O}(N_{\rm g}^2)$ NPCF estimator of Philcox et al. (2021), including a new modification to subtract the disconnected 4PCF contribution (arising from the product of two 2PCFs) at the estimator level. This approach is unlike previous work and ensures that our signal is a robust detection of gravitationally-induced non-Gaussianity. The estimator is validated with a suite of lognormal simulations, and the analytic form of the disconnected contribution is discussed. Due to the high dimensionality of the 4PCF, data compression is required; we use a signal-to-noise-based scheme calibrated from theoretical covariance matrices to restrict to $\sim$ $100$ basis vectors. The compression has minimal impact on the detection significance and facilitates traditional $χ^2$-like analyses using a suite of mock catalogs. The significance is stable with respect to different treatments of noise in the sample covariance (arising from the limited number of mocks), but decreases to $4.7σ$ when a minimum galaxy separation of $14 h^{-1}\mathrm{Mpc}$ is enforced on the 4PCF tetrahedra (such that the statistic can be modelled more easily). The detectability of the 4PCF in the quasi-linear regime implies that it will become a useful tool in constraining cosmological and galaxy formation parameters from upcoming spectroscopic surveys.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑