AI 中文总结
研究利用LiteBIRD卫星在角功率谱水平上对弥漫银河系偏振发射进行光谱特征描述，通过模拟数据计算交叉频率角功率谱并拟合相关分布，能测量多种参数、检测偏差，或排除普朗克数据模型，为银河系ISM研究打开新窗口。
AI 中文摘要
探测宇宙微波背景（CMB）中由暴胀期间产生的张量扰动引起的原初B模式偏振是未来CMB任务的主要科学目标。其成功很大程度上取决于对偏振前景的特征描述，LiteBIRD卫星旨在通过其40至402GHz的15个频段应对这一挑战。本文在角功率谱水平上预测了LiteBIRD对弥漫星际介质（ISM）中偏振尘埃和同步辐射发射进行特征描述的能力。从具有不同前景复杂性的模拟LiteBIRD强度和偏振图中，计算交叉频率角功率谱并将其拟合到尘埃和同步辐射光谱能量分布，分别用修正黑体和幂律建模。发现LiteBIRD能够测量尘埃温度、尘埃和同步辐射光谱指数以及空间相关性，其色散低至σ(T_d)~0.2K、σ(β_d)~0.006、σ(β_s)~0.04和σ(ρ)~10^-2，还能检测并量化因银河系三维发射特性变化而与提议参数模型的偏差。此外，LiteBIRD可能排除普朗克数据所暗示的偏振前景角功率谱的幂律模型，首次检测到弥漫ISM中E模式、B模式和强度之间β_d、T_d和β_s值的差异，突出了银河系物理条件和磁场结构的联合变化。我们得出结论，除了对CMB偏振的详细研究外，LiteBIRD将为控制银河系ISM的物理条件打开一扇新窗口。
英文摘要
Detection of primordial $B$-mode polarization in the cosmic microwave background (CMB) from tensor perturbations generated during inflation is a major scientific goal of future CMB missions. Its success will strongly depend on the characterization of polarized foregrounds, a challenge that the LiteBIRD satellite aims to tackle with its 15 frequency bands ranging from 40 to 402 GHz. In this work, we forecast the ability of LiteBIRD to characterize polarized dust and synchrotron emission in the diffuse interstellar medium (ISM), at the angular power spectrum level. From simulated LiteBIRD intensity and polarization maps with different foreground complexities, we compute cross-frequency angular power spectra and fit them to dust and synchrotron spectral energy distributions, which are modeled by a modified black body and a power law, respectively. We find that LiteBIRD will be able to measure the dust temperature, dust and synchrotron spectral indices and spatial correlation with dispersions as low as $σ(T_{\rm d})\sim0.2$ K, $σ(β_{\rm d})\sim0.006$, $σ(β_{\rm s})\sim0.04$ and $σ(ρ)\sim10^{-2}$, as well as to detect and quantify deviations from the proposed parametric model due to variations of the emission properties in the three dimensions of our Galaxy. Additionally, LiteBIRD is likely to rule out the power-law model of polarized foreground angular power spectra suggested by Planck data. It will also be able to detect differences in the values of $β_{\rm d}$, $T_{\rm d}$, and $β_{\rm s}$ between $E$ modes, $B$ modes, and intensity in the diffuse ISM for the first time, highlighting the joint variations of the physical conditions and the magnetic field structure across the Galaxy. We conclude that in addition to detailed studies of CMB polarization, LiteBIRD will open a new window onto the physical conditions governing the ISM of the Milky Way.
Comments38 pages, 19 figures. Prepared for submission to JCAP
