AI 中文总结
本研究模拟类CSST无狭缝光谱红移样本，分析红移不确定性与干扰天体对BAO测量的影响，发现二者会阻尼BAO信号，BAO重建可显著降低α参数的系统偏差和统计误差。
AI 中文摘要
重子声学振荡（BAO）是测量宇宙学距离、约束暗能量的重要探针。正在运行及近未来的空间望远镜，包括中国空间站巡天望远镜（CSST），将采用无狭缝光谱技术开展星系红移巡天。由于光谱分辨率相对较低及观测效应，测得的红移会存在不确定性并受干扰天体污染。本研究采用近似N体代码FastPM模拟类CSST无狭缝光谱红移（spec-z）样本，考虑高斯分布的红移不确定性和[O III]-Hβ型干扰天体，研究spec-z误差在密度场重建前后对BAO的影响。红移不确定性和干扰天体会阻尼BAO信号，后者还会进一步在功率谱的宽带形状中诱导振荡。我们对干扰天体在传播子（即观测密度场与初始密度场的互相关）及BAO功率谱上的效应进行建模，研究spec-z误差对拟合的各向异性BAO参数α⊥和α∥的影响。结果显示，α⊥和α∥的系统偏差较小，分别主要在0.1%和0.2%以内；即便存在spec-z误差，BAO重建仍可显著降低α参数的系统偏差和统计误差。此外，我们还改变红移不确定性，研究了重建性能。
英文摘要
The baryon acoustic oscillations (BAO) is a vital probe to measure cosmological distances and constrain dark energy. The ongoing and near-future space-based telescopes, including the Chinese Space Station Survey Telescope (CSST), will perform galaxy redshift surveys using slitless spectroscopy. Due to the relatively low spectral resolution and observational effects, there will be uncertainties and interloper contamination in measured redshifts. In this study, we consider the Gaussian-distributed redshift uncertainty and [O III]-H$β$ interlopers in the CSST-like slitless spectroscopic redshift (spec-z) samples, which are simulated using the approximate $N$-body code FastPM. We study the effect of spec-z errors on BAO before and after density field reconstruction. Both the redshift uncertainty and interlopers can damp the BAO signal, and the latter can further induce oscillations in the broadband shape of the power spectrum. We model the interloper effect on the propagator, i.e. the cross-correlation between the observed and initial density fields, as well as on the BAO power spectrum. We study the influence of the spec-z errors on the fitted anisotropic BAO parameters $α_{\perp}$ and $α_{\parallel}$. The resulting systematic bias on $α_{\perp}$ and $α_{\parallel}$ is mild, mostly within $0.1$ per cent and $0.2$ per cent, respectively. Even with the spec-z errors, BAO reconstruction can still significantly reduce the systematic bias and statistical errors on the $α$ parameters. Furthermore, we vary the redshift uncertainty and study the reconstruction performance.
Comments14 pages, 6 (and 7 supplementary) figures, accepted by MNRAS
