AI 中文总结
本研究提出将星系数密度图作为ILC通道，结合CMB实验与大尺度结构巡天，可降低CMB地图的残留前景功率与方差，提升ΛCDM等宇宙学参数的约束精度，为相关实验的设计提供了预期增益依据。
AI 中文摘要
河外前景会在小角尺度上污染宇宙微波背景（CMB）温度地图，限制其在精确宇宙学中的应用。内部线性组合（ILC）是一种知名的抑制这些污染物的技术，但残留的前景功率仍是限制因素。Kusiak等人（2023）提出将星系数密度图作为额外的ILC通道，利用它们与产生这些前景的大尺度结构的相关性来抑制污染。本文将该框架应用于预测近未来及下一代实验中基于CMB的宇宙学参数约束的增益，采用晕模型前景管道和联合TT+TE+EE功率谱的费舍尔预测，在三种配置下量化星系示踪剂辅助ILC清理的改进：增强型西蒙斯天文台（SO）搭配unWISE或类Rubin星系目录，以及未来的CMB-HD配置搭配假设的深星系巡天。研究发现，添加星系示踪剂可使清理后温度图在ℓ~10000处的残留前景功率分别降低约4%（unWISE样本）、22%（类Rubin样本）和32%（未来样本）；对于ℓ~10000处清理后地图的总方差，各组合分别提供8%、24%和17%的改进。对于基础六参数ΛCDM模型，边缘化参数误差棒的减少幅度较小：SO+unWISE组合低于1%，SO+类Rubin示踪剂组合升至约2%；包含相对论性物种有效数N_eff时，SO+类Rubin和CMB-HD+未来示踪剂组合的改进最多为2.2%。这些结果确立了近期CMB实验与当前及即将开展的大尺度结构巡天结合的预期增益。
英文摘要
Extragalactic foregrounds contaminate cosmic microwave background (CMB) temperature maps at small angular scales and limit their utility for precision cosmology. The internal linear combination (ILC) is a well-known technique for suppressing these contaminants, but residual foreground power remains a limiting factor. Kusiak et al. (2023) proposed adding galaxy number-density maps as additional ILC channels, exploiting their correlation with the large-scale structure sourcing these foregrounds to suppress contamination. Here we apply this framework to forecast the gains in CMB-based cosmological parameter constraints from near- and next-generation experiments. Using a halo-model foreground pipeline and a Fisher forecast from joint TT+TE+EE power spectra, we quantify the improvement from galaxy-tracer-assisted ILC cleaning across three configurations: enhanced Simons Observatory (SO) with unWISE or Rubin-like galaxy catalogs, and a futuristic CMB-HD configuration with a hypothetical deep galaxy survey. We find that adding galaxy tracers reduces the residual foreground power in the cleaned temperature map by $\sim4\%$, $\sim22\%$, and $\sim32\%$ at $\ell\sim10,000$ for the unWISE, Rubin-like, and futuristic samples, respectively. For the overall variance of the cleaned map at $\ell\sim10,000$, it provides $8\%$, $24\%$, and $17\%$ improvements for each combination. The resulting reduction in marginalized parameter error bars is modest for the base six-parameter $Λ$CDM model: sub-percent for SO+unWISE, rising to $\sim2\%$ for SO+Rubin-like tracer. Including the effective number of relativistic species $N_{\rm eff}$, we find at most $2.2\%$ improvements for both SO+Rubin-like and CMB-HD+Futuristic tracer. These results establish the expected gains from combining near-term CMB experiments with current and forthcoming large-scale-structure surveys.
Comments18 pages, 9 figures, 3 tables
