Unveiling the primordial universe

尽管我们对星系的形成和演化的理解在理论和观测上取得了很大进展，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很大的影响，因此揭示这一过程至关重要。虽然已经进行了几项再电离研究，但没有一项包括正确建模所需的所有物理学。这是因为这个问题在计算上非常具有挑战性，而且到目前为止，还没有一个研究小组拥有所有的专业知识和技术手段来解决这个问题。目前，我们是唯一一个拥有宇宙学应用的3D辐射传输代码的小组，该代码能够跟踪Ly射线，UV和X射线光子的传播，并允许计算H，H+，He，He+，He++，He+，He自由电子和IGM温度。我们计划研究由于两个恒星（主要在紫外线发射）和类星体（具有较硬的光谱）的再电离，并在同一时间，遵循的传播的Ly光子是重要的21厘米线从中性氢的可观测性。有了这些改进的模型，我们将产生可靠的预测观测21厘米的信号，这被认为是最终的观测工具，把严格的约束再电离的历史。

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.