标题： 基于物理激励误差建模的色散波束实验中全局21厘米谱的鲁棒提取 显示英文标题

标题： Robust Extraction of Global 21 cm Spectrum from Experiments with a Chromatic Beam Based on Physics-Motivated Error Modeling

摘要： 从宇宙黎明和再电离时代中提取天空平均的21厘米信号面临重大挑战。明亮且各向异性的银河系前景，其亮度比21厘米信号高4-5个数量级，当与不可避免的色散天线波束卷积时，会引入额外的光谱结构，这些结构很容易模仿真实的21厘米信号。在本文中，我们研究了月球轨道实验中的信号提取，其中天线在轨道上快速移动，必须使用多个轨道的数据。我们提出了一种基于物理原理且相关的前景和测量误差建模方法。通过根据光谱指数分布将天空划分为多个区域，并考虑建模误差的完整协方差，我们使用Discovering the Sky at the Longest wavelength lunar orbit experiment的模拟数据同时拟合前景和21厘米信号。即使对于一个色散性相对较高的测试天线，该方法也能成功地从模拟数据中提取出各种幅度的21厘米信号。这种方法对中等程度的天线色散具有鲁棒性，显著放松了对天线设计和制造的严格要求，为未来的21厘米全球信号实验提供了实用的解决方案，无论是在地面还是在空间。 显示英文摘要

摘要： The extraction of the sky-averaged 21 cm signal from Cosmic Dawn and the Epoch of Reionization faces significant challenges. The bright and anisotropic Galactic foreground, which is 4 - 5 orders of magnitude brighter than the 21 cm signal, when convolved with the inevitably chromatic beam, introduces additional spectral structures that can easily mimic the real 21 cm signal. In this paper, we investigate the signal extraction for a lunar-orbit experiment, where the antenna moves fast in orbit and data from multiple orbits have to be used. We propose a physics-motivated and correlated modeling of both the foreground and the measurement errors. By dividing the sky into multiple regions according to the spectral index distribution and accounting for the full covariance of modeling errors, we jointly fit both the foreground and the 21 cm signal using simulated data for the Discovering the Sky at the Longest wavelength lunar orbit experiment. This method successfully extracts the 21 cm signals of various amplitudes from the simulated data even for a testing antenna with a relatively high level of chromaticity. This approach, which is robust against moderate beam chromaticity, significantly relaxes the stringent design and manufacturing requirements for the antenna, offering a practical solution for future 21 cm global signal experiments either on the ground or in space.