Unveiling the primordial universe

尽管我们对星系形成和演化的理解在理论和观测方面取得了很大进展，但许多基本问题仍然只有部分答案，特别是那些与宇宙再电离细节有关的问题。由于它对星系的形成和演化有着强烈的影响，因此阐明这一过程至关重要。虽然已经进行了几项再电离研究，但没有一项研究包括正确建模所需的所有物理条件。这是因为这个问题在计算上非常具有挑战性，因为到目前为止，在该领域工作的研究小组都没有所有的专业知识和技术手段来附加它。目前，我们是唯一一个拥有用于宇宙学应用的3D辐射传输代码的团队，该代码能够跟踪Ly、UV和x射线光子的传播，并允许计算H、H+、He、He+、He+、He+、自由电子和IGM温度的演化。我们计划研究由恒星（主要发射紫外线）和qso（具有较硬光谱）引起的再电离，同时跟踪Ly光子的传播，这对于从中性氢的21厘米线的可观测性很重要。利用这些改进的模型，我们将对21厘米信号的观测结果进行可靠的预测，这被认为是对再电离历史进行严格约束的最终观测工具。

Despite much recent theoretical and observational progress in our understanding of the formation and evolution of galaxies, many fundamental questions remain only partially answered, in particular, those related to the details of cosmic reionization. As it has a strong impact on the formation and evolution of galaxies, it is crucial to shed light on this process. Although several reionization studies have been done, none includes all the physics required for its proper modeling. This is because the problem is computationally very challenging and because to this date no research group working in the field has all the expertise and the technical means to attach it. Right now we are the only group with a 3D radiative transfer code for cosmological application that is able to follow the propagation of Ly, UV and x-ray photons and allows to calculate the evolution of H, H+, He, He+, He++, free electrons and IGM temperature. We plan to study the reionization due to both stars (which emit mainly in the UV) and QSOs (with a harder spectrum) and, at the same time, to follow the propagation of the Ly photons which are important for the observability of the 21 cm line from neutral hydrogen. With these improved models we will produce reliable predictions for observations of 21 cm signal, which is believed to be the ultimate observational tool to put stringent constraints on the reionization history.