The First Billion Years

第一个十亿年

• 批准号: 2277533
• 金额: --
• 依托单位: University of Cambridge
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2019
• 资助国家: 英国
• 起止时间: 2019 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2277533
• 关键词: First; Billion; Years

In the course of my PhD I want to advance the field of what we call "21cm cosmology". Cosmology is the study of the universe on the largest scales and how it evolved over time. 21cm refers to the very weak signal emitted by neutral Hydrogen - this atom can emit or absorb radiation of that wavelength as long as it is not ionized. This happens everywhere in the universe, however the effect is rare and therefore can only be seen when observing large amounts of gas.The early universe (between one million and one billion years of age) is essentially filled with this neutral Hydrogen and we can use the cosmic microwave background, radiation emitted a few hundred thousand years after the big bang, as a flashlight shining through the gas and observe it's absorption or emission behaviour over time.I think much progress can be made by combining methods and information from classical cosmology with the novel observations of the neutral Hydrogen signal. We know very little about the first stars in the universe and a wealth of models has been developed. But using information from the polarization of the cosmic microwave background allows us to limit these possibilities and get a better idea of that time.On the other hand those novel observations can be used to improve our current measurements of the distribution of matter in the universe and the growth of structures with time. We often use galaxies as tracers of the overall distribution of matter in the universe. However they do not paint a complete picture since galaxies only form under certain conditions and we cannot observe the faintest galaxies. Measuring neutral Hydrogen via the 21cm signal gives us a different view and allows us to estimate and correct problems with other methods.Finally this can give us hints or constraints on the nature of Dark Matter as we can probe previously unexplored areas of cosmologies.

在我的博士学位课程中，我想推进我们所说的“21厘米宇宙学”领域的发展。宇宙学是对宇宙最大尺度及其随时间演化的研究。 21cm是指中性氢发出的非常微弱的信号——这种原子只要不被电离就可以发射或吸收该波长的辐射。这种现象在宇宙中随处可见，但是这种效应很少见，因此只能在观察大量气体时才能看到。早期宇宙（年龄在100万到10亿年之间）本质上充满了这种中性氢，我们可以使用宇宙微波背景，即大爆炸后数十万年发出的辐射，作为穿过气体的手电筒，观察它随着时间的推移的吸收或发射行为。我认为通过组合方法可以取得很多进展 以及来自经典宇宙学的信息以及对中性氢信号的新颖观察。我们对宇宙中第一批恒星知之甚少，但已经开发出了丰富的模型。但是，使用来自宇宙微波背景偏振的信息可以让我们限制这些可能性，并更好地了解那个时间。另一方面，这些新颖的观测结果可以用来改进我们目前对宇宙中物质分布和结构随时间增长的测量。我们经常使用星系作为宇宙中物质总体分布的示踪剂。然而，它们并没有描绘出完整的图景，因为星系仅在某些条件下形成，而我们无法观察到最微弱的星系。通过 21 厘米信号测量中性氢给我们带来了不同的视角，使我们能够用其他方法估计和纠正问题。最后，这可以给我们关于暗物质性质的提示或限制，因为我们可以探测以前未探索的宇宙学领域。