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)。普朗克卫星已经很好地测量了温度各向异性，这建立了目前的协调宇宙模型。然而，CMB还没有被充分利用：对CMB偏振的测量提供了一个探索宇宙早期发生的物理过程的机会。线偏振信号分解为E-模和B-模贡献，在大角度尺度上探测到B-模偏振信号将证明原始引力波的存在。这将预示着膨胀，并为在大统一理论(GUT)能量尺度上探索物理学提供了一个平台。因此，探测B模式信号是未来CMB观测的主要目标，例如地面西蒙斯阵列和西蒙斯天文台，以及卫星LiteBIRD。感兴趣的偏振信号很微弱，因此有必要进行最佳观测策略、仪器设计和数据分析。数据中类似B模式签名的虚假信号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缺陷。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