Star formation in galaxies from the Epoch of Reionisation to the present day with JWST

第一个星系看起来与今天宇宙中令人敬畏的螺旋和椭圆星系非常不同。光速是有限的，这意味着一个物体离我们越远，我们看到它的时间就越早。这让我们得以瞥见宇宙蹒跚学步阶段的混乱、动荡和不稳定的星系，这要归功于哈勃太空望远镜凝视遥远的太空。与此同时，地面和太空观测站已经建立了一个更完整的，细致入微的青少年时期的图片，通过它的当前，相对有序，成人状态。但是这张照片的大部分仍然缺失，需要下一个伟大的太空天文台，詹姆斯韦伯太空望远镜（JWST），开始填补它们。我将填补的照片的一部分是调查星系如何形成它们的恒星，从早期的宇宙到今天。从构成恒星孕育所的气体的性质，我将研究在特定的恒星生成过程中存在哪些元素，以及从恒星如何使气体发光来了解恒星本身。我将探测光谱，寻找平稳演化或突然变化的星星形成的示踪物，以表明星星形成在不同时期的不稳定性。我将寻找吸积超大质量黑洞的特征，这些系统非常强大，我们认为它们能够加热气体并阻止整个星系形成更多的恒星。这是我们第一次能够用同样的观测示踪剂来做这些研究，这些示踪剂曾用于解开影响局部星星形成的因素。这项研究的一个重要目的是用一种一致的方法来描绘这些因素从宇宙的婴儿期到现在的演变。在天文学中，我们总是面临这样的问题：我们的观测只是过去的快照，我们没有办法追踪单个星系随时间的演变。因此，我将使用星系演化的各种流体动力学模拟来解释这个程序提供的人口统计数据。最重要的是，定制的COCKATOO模拟跟踪不同恒星类型中形成的金属，以及它们喷射到空间之间，准备混合，冷却并形成随后的恒星世代。

The first galaxies looked very different to the awe-inspiring spirals and ellipticals that populate the Universe today. The finite speed of light means that the further away an object is to us, the further back in time we are seeing it. This has permitted us to glimpse the messy, turbulent and erratic galaxies populating the toddler stage of the Universe, thanks to the Hubble space telescope peering into distant space. Meanwhile, ground and space based observatories have been building a more complete, nuanced picture of the teenage years through to it's current, relatively ordered, adult state. But huge chunks of the picture are still missing and it will take the next great space-based observatory, the James Webb space telescope (JWST), to start filling them in.The part of the picture I will be filling in is investigating how galaxies form their stars, from the early Universe to the present day. From the properties of the gas making up the stellar nurseries I will investigate what elements are present for that particular stellar generation, as well as learning about the stars themselves from how they make that gas shine. I will probe spectra for tracers of smoothly evolving or abruptly changing star formation, to indicate how erratic the star formation is at different epochs. I will search for signatures of accreting supermassive black holes, systems that are so powerful we think they are able to heat gas and prevent further stars from forming throughout a whole galaxy. For the first time we will be able to do these studies with the same observational tracers used to disentangle factors affecting star formation locally. A significant aim for this research is to plot the evolution of these factors from the Universe's infancy to the present day using a consistent approach.In astronomy we are always faced with the problem that our observations are but snapshots of the past, and we have no way to trace an individual galaxy's evolution with time. I will therefore be using various hydrodynamic simulations of galaxy evolution to interpret the population statistics provided by this program. Not least, the bespoke COCKATOO simulation traces metals formed within different stellar types, as well as their ejection into the space between, ready to mix, cool and form subsequent stellar generations.