Solving cosmological questions in strong gravity

我的工作试图回答两个问题，这是宇宙学的核心——理解宇宙是由什么组成的，以及它从何而来。首先，什么是暗物质？暗物质是我们宇宙的主要组成部分之一，但到目前为止，人们只能通过它对恒星和星系的引力作用来探测到它。我将确定构成暗物质的粒子的关键属性，比如质量和自旋，是如何影响暗物质在黑洞周围的聚集的。然后，我将研究这些暗物质环境如何影响引力波和电磁信号，将这些“多信使”观测与粒子物理学联系起来。第二，宇宙是如何开始的？我将探索宇宙在最早期的行为，即使是很小的缺陷也可能以混乱的方式爆炸。目的是了解我们的宇宙是如何从大爆炸变成我们所观察到的均匀膨胀状态的——非均匀区域是同步的吗？新型物质能否充当“宇宙平滑剂”？我们是如何逃脱宇宙收缩的命运的？为了回答这些问题，我使用了“数值相对论”计算技术。这些工具的开发是为了让LIGO/Virgo的引力波探测器网络能够解释它们从黑洞和中子星合并中看到的信号，但现在却吸引了理论物理其他领域的关注。我正在率先将它们应用于宇宙学问题，这是一个新兴领域，利用现代超级计算的力量来回答关于我们宇宙的长期问题。

My work seeks to answer two questions that go to the heart of cosmology - understanding what the Universe is made of, and where it came from.Firstly, what is dark matter? Dark matter is one of the main components of our Universe, but so far it has only been detected via its gravitational effect on stars and galaxies. I will identify how key properties of the particles that make up the dark matter, such as mass and spin, affect its clustering around black holes. I will then investigate how these dark matter environments affect gravitational wave and electromagnetic signals, linking these "multimessenger" observations to particle physics.Secondly, how did the Universe begin? I will explore the behaviour of our universe at the earliest times, when even small imperfections may blow up in a chaotic way. The aim is to understand how our universe emerged from a Big Bang to the state of uniform expansion that we observe - did non-uniform regions become synchronised? Can new types of matter act as a "cosmological smoother"? How did we escape the fate of a contracting universe?To answer these questions, I am using "numerical relativity" computational techniques. These tools were developed to allow the LIGO/Virgo network of gravitational wave detectors to interpret the signals they see from merging black holes and neutron stars, but are now attracting attention in other areas of theoretical physics. I am pioneering their application to cosmological questions, a nascent field which harnesses the power of modern supercomputing to answer long-standing questions about our Universe.