论文标题
用大规模结构的双光谱约束有效的中微子物种
Constraining effective neutrino species with bispectrum of large scale structures
论文作者
论文摘要
相对论和自由流粒子（如中微子）在大规模结构（LSS）中留下烙印，提供了有效中微子物种$ n _ {\ rm eff} $的有效数量的探针。在本文中，我们使用Fisher形式主义来预测$ n _ {\ rm eff} $从LSS的Bispectrum（b）进行当前和未来的Galaxy Redshift Surveys的约束，特别是使用Baryon声学振荡（BAOS）的信息。对树级的星系双光谱进行建模，我们发现将双光谱约束添加到Planck当前的CMB约束中可以改善$ n _ {\ rm eff} $的仅限Planck的约束，这取决于10 \％-40 \％。与先前在文献中探索的Planck+功率谱（P）约束相比，使用Planck+P+B提供了进一步的改善，约为5 \％-30 \％。除了仅使用Bao Wiggles外，我们还使用包括Wiggles和宽带信息（受系统挑战的范围）的总信息进行探索，通常会产生更好的结果。最后，我们利用BISPECTRUM中BAO的干扰功能选择了三角形的子集，其中最多信息在$ n _ {\ rm eff} $上。这允许在保留大多数信息的同时降低计算成本，以及避免直接应用于Bispectrum的某些缺点，当前的Wiggle提取算法对功率谱有效。总而言之，我们的研究验证了当前对$ n _ {\ rm eff} $的普朗克约束可以在下一代CMB实验（如CMB阶段4）之前，可以在Galaxy Surveys的帮助下得到显着改善。
Relativistic and free-streaming particles like neutrinos leave imprints in large scale structures (LSS), providing probes of the effective number of neutrino species $N_{\rm eff}$. In this paper, we use the Fisher formalism to forecast $N_{\rm eff}$ constraints from the bispectrum (B) of LSS for current and future galaxy redshift surveys, specifically using information from the baryon acoustic oscillations (BAOs). Modeling the galaxy bispectrum at the tree-level, we find that adding the bispectrum constraints to current CMB constraints from Planck can improve upon the Planck-only constraints on $N_{\rm eff}$ by about 10\% -- 40\% depending on the survey. Compared to the Planck + power spectrum (P) constraints previously explored in the literature, using Planck+P+B provides a further improvement of about 5\% -- 30\%. Besides using BAO wiggles alone, we also explore using the total information which includes both the wiggles and the broadband information (which is subject to systematics challenges), generally yielding better results. Finally, we exploit the interference feature of the BAOs in the bispectrum to select a subset of triangles with the most information on $N_{\rm eff}$. This allows for the reduction of computational cost while keeping most of the information, as well as for circumventing some of the shortcomings of applying directly to the bispectrum the current wiggle extraction algorithm valid for the power spectrum. In sum, our study validates that the current Planck constraint on $N_{\rm eff}$ can be significantly improved with the aid of galaxy surveys before the next-generation CMB experiments like CMB-Stage 4.
