AI 中文总结
研究利用双谱中的重子声学振荡信号检测和刻画相对速度效应，通过扩展框架、引入新技术提取参数，经模拟验证可提高统计约束能力，量化相对速度分量影响，能打破参数简并，为星系巡天提供有力探测工具。
AI 中文摘要
我们评估双谱中的重子声学振荡（BAO）信号，将其作为检测和刻画相对速度效应的工具。我们扩展了现有框架，提出了红移空间树级双谱的更新模型，全面纳入了所有相对速度项。我们引入一种新颖、无偏的技术，仅从双谱单极子中提取各向同性BAO膨胀参数（$\alpha_{\rm iso}$）。经N体模拟验证，这种基于模板的提取成功恢复了声学尺度，并在与重建前功率谱串联分析时，将统计约束能力提高了约30%，为标准重建后管道提供了有力补充。我们量化了各个相对速度分量如何扭曲两点和三点统计量。我们发现这些效应在两个探测器之间提取的$\alpha_{\rm iso}$中引起明显的系统偏移。对于$b_{v^2}=\pm0.05$，系统差异高达2%；对于$b_{\delta^{bc}}\le-2$，高达20%。这些差异表明，独立功率谱和双谱BAO测量的直接比较可以打破参数简并，并分离这些偏差的幅度。最后，我们提供了一个检测和约束三个相关相对速度偏差参数的具体方法，表明联合分析对$b_{v^2}$和$b_{\delta^{bc}}$幅度高度敏感。这确立了双谱BAO作为当前和下一代星系巡天的强大宇宙学探测器，既是标准分析的交叉检验，也是对抗系统偏差的关键诊断工具。
英文摘要
We evaluate the Baryon Acoustic Oscillation (BAO) signal in the bispectrum as a tool to detect and characterize the relative velocity effect. We extend the existing framework by presenting an updated model for the redshift-space tree-level bispectrum that comprehensively incorporates all relative velocity terms. We introduce a novel, unbiased technique to extract the isotropic BAO dilation parameter ($α_{\rm iso}$) solely from the bispectrum monopole. Validated against N-body simulations, this template-based extraction successfully recovers the acoustic scale and enhances the statistical constraining power by $\sim30\%$, when analyzed in tandem with the pre-reconstruction power spectrum, offering a powerful complement to standard post-reconstruction pipelines. We quantify how individual relative velocity components distort both two- and three-point statistics. We find that these effects induce distinct systematic shifts in the extracted $α_{\rm iso}$ between the two probes. We find systematic discrepancies of up to $2\%$ for $b_{v^2}=\pm0.05$ and up to $20\%$ for $b_{δ^{bc}}\le-2$. This differences demonstrate that a direct comparison of independent power spectrum and bispectrum BAO measurements can break parameter degeneracies and isolate the amplitude of these biases. Finally, we provide a concrete prescription to detect and constrain the three associated relative velocity bias parameters, showing that a joint analysis is highly sensitive to the $b_{v^2}$ and $b_{δ^{bc}}$ amplitudes. This establishes the bispectrum BAO as a robust cosmological probe for current and next-generation galaxy surveys, serving both as a cross-check for standard analyses and a crucial diagnostic tool against systematic biases.
Comments28 pages, 9 figures
