GR Dynamics of Stochastic Inflation

这个博士项目将通过将随机膨胀方法与完全非线性的广义相对论演化相结合，从膨胀模型中进行定量的统计预测，来推进早期的宇宙膨胀理论，该理论解释了星系的起源和宇宙中的大尺度结构。由于广义相对论产生的非线性，以及驱动通货膨胀的势可能是相互作用的事实，非高斯签名固有地存在于原始涨落中。这个项目的目标是对非线性通货膨胀动力学进行分析和数值模拟，以便做出双谱(三点)和其他高阶相关器预测，涵盖范围更广的通货膨胀情景(包括那些具有多个领域的情景)；这是相互竞争的通货膨胀模型之间的一个重要区别，可以用来从观测上区分它们。这将通过利用新的GRChombo数值相对论管道来使用全3D广义相对论模拟来计算这些非线性效应来实现，并通过包含在膨胀过程中放大的量子涨落来增强它。后者将被实现为随机源项，并被集成到GRChombo演化例程中，而GRChombo演化例程将通过来自有效场论的微扰分析计算来确定。DAMTP宇宙学家，由博士导师Shellard领导，已经能够通过使用创新的可分离技术(模式管道)从宇宙微波背景(CMB)的普朗克卫星地图中提取和重建温度和偏振双谱；这现正被应用于来自CMB实验(西蒙斯天文台)和星系调查(SDSS、DES和其他)的新观测数据集。由该PHD项目产生的随机非线性GR模拟的3D场将直接服从于这些技术的分析，推进了膨胀理论与宇宙学数据的详细对抗

This PhD project will advance the early universe theory of inflation, which explains the origin of galaxies and large-scale structure in the Universe, by merging stochastic inflation methods with fully nonlinear General relativistic evolution to make quantitative statistical predictions from inflationary models. Non-Gaussian signatures are inherently present in primordial fluctuations due to the nonlinearities produced by both general relativity and the fact that the potential responsible for driving inflation may be interacting. The goal of this project is to analytically and numerically model nonlinear inflationary dynamics in order to make bispectrum (three-point) and other higher-order correlator predictions which encompass a much broader range of inflationary scenarios (including those with multiple fields); this is an important discriminant between competing inflation models that can be used to distinguish them observationally. This will be achieved by exploiting the new GRChombo numerical relativity pipeline to compute these nonlinear effects using full 3D general relativistic simulations, augmenting it by the inclusion of quantum fluctuations that get amplified during Inflation. The latter will be implemented as stochastic source terms to be integrated within the GRChombo evolution routines and which, in turn, will be determined via perturbative analytic computations from effective field theory. DAMTP cosmologists, led by the PhD supervisor Shellard, have been able to constrain a wide range of inflationary scenarios by using innovative separable techniques (the MODAL pipeline) to extract and reconstruct the temperature and polarization bispectra from Planck satellite maps of the cosmic microwave background (CMB); this is now being applied to new observational data sets from both CMB experiments (Simons Observatory) and galaxy surveys (SDSS, DES and beyond). The resulting 3D fields of the stochastic nonlinear GR simulations from this PhD project will be directly amenable to analysis by these techniques, advancing the detailed confrontation of inflationary theory with cosmological data