Constraining the physics of the early Universe with CMB polarisation

也许最有用的宇宙学探测器是宇宙微波背景（CMB）。普朗克卫星对温度的各向异性进行了很好的测量，建立了目前的一致宇宙学模型。然而，宇宙微波背景辐射还没有被充分利用：测量宇宙微波背景辐射的偏振提供了一个机会来探测在非常早期的宇宙中发生的物理过程。线性偏振信号被分解为E模式和B模式的贡献，其中在大角度尺度上检测到B模式偏振信号将证明原始引力波的存在。这将是通货膨胀的指示，并提供了一个平台，探索物理学在大统一理论（GUT）的能量尺度。因此，B模式信号的检测是未来CMB观测的主要目标，例如地面Simons阵列和Simons天文台以及LiteBIRD卫星。感兴趣的偏振信号是微弱的，因此需要优化观测策略，仪器设计和数据分析。数据中的伪信号与B模式特征不符，可能是由仪器和天空扫描缺陷产生的，因此必须仔细考虑这些问题。该项目的目的是优化仪器设计，扫描策略，和数据分析技术，为未来的CMB实验使用分析技术和计算机模拟

Perhaps the most useful cosmological probe is the Cosmic Microwave Background (CMB). Thetemperature anisotropies have been measured extremely well by the Planck satellite and thishas established the current concordance cosmological model. However, the CMB has notbeen utilised fully yet: measurements of the CMB polarisation offer an opportunity to probethe physical processes that occurred in the very early Universe. The linear polarisation signalis decomposed into E-mode and B-mode contributions, where the detection of a B-modepolarization signal on large angular scales would demonstrate the existence of primordialgravitational waves. This would be indicative of inflation and provide a platform for exploringphysics at the Grand Unified Theory (GUT) energy scale. The detection of the B-mode signalis thus a major goal of future CMB observations, such as the ground-based Simons array andSimons Observatory, and the satellite LiteBIRD.The polarisation signal of interest is faint and as such optimal observation strategy,instrument design, and data-analysis is necessary. Spurious signals in the data that resemblethe B-mode signature can be generated by instrument and sky scanning imperfections, assuch these must be carefully accounted for. This project's aim is the optimisation of theinstrument design, scan strategy, and data analysis techniques for future CMB experimentsusing analytic techniques and computer simulations