Shear-kSZ：利用kSZ层析和弱引力透镜的物质-电子功率谱新估计量
Shear-kSZ: A New Estimator for the Matter-Electron Power Spectrum from kSZ Tomography and Weak Lensing
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中文总结 AI 辅助
该研究提出 Shear-kSZ 新估计量，结合 kSZ 层析与弱引力透镜测量物质-电子功率谱，可确定重子抑制因子，预测当前及未来巡天能实现高精度测量。
中文摘要 AI 辅助
我们提出了一种用于电离气体-物质功率谱的新估计量，该估计量将运动学 Sunyaev-Zel'dovich（kSZ）场与视线速度场及弱引力透镜收敛图相关联。与标准堆叠 kSZ 估计量类似，该估计量可分解为可校准的速度核乘以物质-电子交叉功率谱 $P_{me}(k)$。由于该估计量可获取全物质分布的 $P_{me}(k)$，而非标准堆叠 kSZ 估计量中特定偏置示踪剂周围的 $P_{me}(k)$，因此它能确定物质功率谱的重子抑制因子 $S(k)$，这是第四阶段宇宙剪切的主要天体物理系统误差之一。我们推导了该估计量的解析表达式并通过模拟验证，发现其符合度达到百分级。由于其宇称结构，宇宙微波背景（CMB）前景的贡献会相互抵消。采用类西蒙斯天文台（Simons Observatory）噪声和波束的真实 CMB 温度图、通过对类 DESI 发光红星系（LRG）应用线性速度重建得到的平滑速度场，以及类 LSST 高红移源（可抑制内禀 alignment 和增强因子的影响），我们预测在 $f_{\rm sky}=0.2$ 时可实现 $16\boldsymbol{\times}\boldsymbol{\times}$ 测量（对应 $S(k)$ 的 1% 测量精度），表明该估计量是当前巡天（如 LSST 和 \textit{Euclid}）可直接测量的目标。由于信噪比由 CMB 噪声而非透镜深度主导，我们预计利用早期 LSST 数据发布即可达到约 $10\boldsymbol{\times}\boldsymbol{\times}$ 的探测水平，而高级西蒙斯天文台（Advanced Simons Observatory）预计可使信噪比大幅提升 2 倍。本文中我们以类 DESI LRG 作为前景样本，低红移样本则能提供更广泛的背景源样本。
英文摘要
We propose a new estimator for the ionized gas--matter power spectrum, which correlates the kinematic Sunyaev--Zel'dovich (kSZ) field with the line-of-sight velocity field and the weak-lensing convergence map. Analogously to the standard stacked kSZ estimator, this estimator factorizes into a calibratable velocity kernel multiplying the matter--electron cross-power spectrum, $P_{me}(k)$. Because the estimator accesses $P_{me}(k)$ for the full matter distribution rather than around a specific biased tracer as is the case with the standard stacked kSZ estimator, it allows us to determine the baryonic suppression of the matter power spectrum, $S(k)$, one of the dominant astrophysical systematics for Stage-IV cosmic shear. We derive and validate an analytical expression for the estimator against simulations, finding percent-level agreement. Due to its parity structure, contributions from cosmic microwave background (CMB) foregrounds cancel. Using a realistic CMB temperature map with Simons Observatory-like noise and beam, a smoothed velocity field as obtained via linear velocity reconstruction applied to DESI-like luminous red galaxies (LRGs), and LSST-like sources at high redshifts, which suppresses the effect of intrinsic alignments and boost factors, we forecast a $16σ$ measurement over $f_{\rm sky}=0.2$ (corresponding to 1\% measurement of $S(k)$), establishing our estimator as a readily measurable target for current surveys, e.g., LSST and \textit{Euclid}. Because the signal-to-noise is dominated by CMB noise rather than lensing depth, we expect a detection already at $\sim10σ$ with early LSST data releases. Substantial (factor of 2) gains in signal-to-noise are expected with Advanced Simons Observatory. While here we focus on DESI-like LRGs as the foreground sample, lower-redshift samples provide an even wider array of source samples in the background.
