Gravitational wave cosmology for LISA

最近，一种探索早期宇宙的新工具受到了极大的关注，这就是被称为引力波的“时空涟漪”。在过去的几年里，我们第一次用它们来直接观察黑洞的合并。一旦产生，引力波就不会与其他任何东西相互作用，因此它们不仅可以为天体物理过程提供一个窗口，还可以为早期宇宙的物理学提供一个窗口。利用引力波，我们可以看到宇宙还不透明的时候，因此，利用引力波探测器可以看到许多令人兴奋的东西。我的项目特别关注引力波的宇宙源，其波长比我们在地球上探测到的波长要长。欧洲航天局将于2034年发射一个名为丽莎的天基探测器。由于探测器臂在太空中的长度可能是地球上的许多倍，丽莎使命非常适合观察希格斯玻色子本身“开启”前后产生的引力波。在我的研究期间，我将使用计算机模拟来预测丽莎应该看到希格斯玻色子“开启”的证据。我将把这一点与粒子物理学联系起来，粒子物理学也是在像LHC这样的对撞机上进行更传统的研究--通过采用简单的模型，增加一两个额外的粒子，我可以寻找LHC不能排除的情况，但从宇宙学的角度来看，这些情况是有希望的。

Recently, a new tool for exploring the early universe has been receiving a great deal of attention, namely the "ripples in spacetime" termed gravitational waves. In the past couple of years we have used them to directly observe mergers of black holes for the first time. Once produced, gravitational waves do not interact with anything else, so they can provide a window not only into astrophysical processes, but also into the physics of the early universe. With gravitational waves we can see back to a time when the universe was still optically opaque.There are therefore many exciting things that can be seen with gravitational wave detectors. My project in particular concerns cosmological sources of gravitational waves on longer wavelengths than we can detect on Earth. The European Space Agency will launch a space-based detector in 2034, termed LISA. Since the detector arms can be many times longer in space than on Earth, the LISA mission is well placed to see gravitational waves produced around the time the Higgs boson itself 'turned on'.During my Fellowship I will use computer simulations to predict what evidence LISA should see of the Higgs boson 'turning on'. I shall connect this to the particle physics that is more conventionally studied at colliders like the LHC, too - by taking simple models which add one or two extra particles, I can look for cases that the LHC cannot rule out but that are promising from a cosmological point of view.