Research in planetary formation, astrophysics, and cosmology at Bristol

这项提议是为了资助布里斯托尔大学地球科学和物理学院对行星形成、天体物理学、宇宙学和数据处理的尖端研究。这项工作的第一个要素涉及了解行星形成的早期阶段。有关这些过程的信息既可以从我们太阳系的陨石化学中收集，也可以从天文学上从所谓的过渡盘的观察中收集到。过渡盘是指具有红外光谱的恒星，其红外光谱表明在一定温度范围内有许多尘埃在轨道上运行，但在恒星附近有一个无尘埃区域。理论表明，被这种过渡盘包围的恒星目前正在形成行星，但由于缺乏对存在的尘埃类型的了解，缺乏关于尘埃如何转化为行星的准确计算，以及缺乏能够检验这些模型的详细成像，我们对行星系统形成的这一重要阶段的理解受到阻碍。我们将通过观察不同种类的尘埃颗粒(由不同的早期恒星爆炸形成)是如何在我们太阳系历史的早期，超过40亿年前被分类，然后聚集成不同类型的陨石落到地球上，来开始解决这些问题。然后，我们可以利用这些信息来改进尘埃如何转化为行星的计算机模型，并更好地预测当我们使用新一代望远镜(阿塔卡马大毫米阵列)时我们应该看到什么，该望远镜具有观察这些圆盘的特殊能力。当我们观察时，如果我们发现模型和数据之间有很好的一致性，这将给我们对我们的理论的信心，否则将刺激新的行星形成理论的工作。工作的第二部分同样是关于物体的形成，但在整个星系、星系团和整个宇宙的更大范围内。我们是英国一个大型项目的带头人，该项目旨在通过位于星系周围的气体的X射线发射来寻找遥远的年轻星系(星系团)。在接下来的四年里，这颗绕轨道运行的XMM卫星将发现数百个这样的高红移星系团，通过研究它们的X射线发射和它们对微波背景辐射的阴影，我们将能够测量它们的质量，从而更多地了解引力是如何将宇宙中的结构从原始的扩散气体中拉出来的。除了X射线之外，星系团的主要指标是它们的星系数量，星系团中星系的类型和质量范围随着时间的推移而变化，可能是由于一些不同的物理原因。我们将改进我们对接近我们的人口(以及在当代宇宙中的人口)的知识，作为与新集群中的人口进行比较的参考。理论告诉我们，如果没有某种方法来减缓重力的影响，那么我们所看到的星系就不可能存在，这种方法是通过某种反馈过程来阻止气体塌缩成一个超大质量的物体。据推测，大部分反馈是由于星系中心超大质量黑洞中发生的现象，我们将通过观察这些超大质量黑洞的强引力X射线信号(将它们与我们银河系中已知的较小黑洞进行比较)以及通过喷流和其他外流将能量从黑洞附近涌入更广泛的环境的过程来研究这一过程。我们还将回顾我们可以详细研究的最遥远的星系和星系团，看看我们是否能够理解形成过程的开始。这项工作的最后一个要素涉及开发一套关键的计算机代码，我们和许多其他研究人员使用它来检查天文数据。这些代码以TOPCAT为核心，向公众开放并广受欢迎，但必须加以改进，以跟上不断变化的数据和计算需求。

This proposal is for a grant to cover cutting-edge research into planetary formation, astrophysics, cosmology, and data-handling at the University of Bristol in the schools of Earth Sciences and Physics.The first element of the work involves understanding the early phases of planet formation. Information on these processes can be gleaned from both the chemistry of meteorites in our own solar system and astronomically from observations of so-called transitional disks - stars with infra-red spectra that indicate much orbiting dust at a range of temperatures, but with a dust-free region close to the star. Theories suggest that stars surrounded by such transitional disks are currently forming planets, but our understanding of this important phase in the formation of planetary systems is hampered by lack of knowledge of the types of dust that are present, lack of accurate calculations on how dust is converted into planets, and lack of detailed imaging that can test those models. We will start to solve these problems by seeing how different sorts of dust grains (formed from the explosions of diverse earlier stars) were sorted early in our solar system's history, over four thousand million years ago, and subsequently aggregated into the different types of meteorites that fall to Earth. We can then use this information to improve our computer models of how the dust converts into planets, and to make better predictions of what we should see when we use a new generation telescope (the Atacama Large Millimeter Array) which has special capabilities for observing these disks. If, when we do look, we see good agreement between the models and the data, this will give us confidence in our theories or otherwise will spur work into new theories of planet formation.The second part of the work is again about the formation of objects, but on the much larger scale of whole galaxies, clumps of galaxies, and the Universe as a whole. We are UK leads for a large project to find distant and young clumps of galaxies (clusters) through the X-ray emission of the gas that lies around those galaxies. Over the next four years this survey with the orbiting XMM satellite will dicover hundreds of these high-redshift clusters, and by studing their X-ray emission and the shadows that they cast on the microwave background radiation we will be able to measure their masses and so to find out more about how gravity pulls structures in the Universe out of the original diffuse gas. The major indicator of clusters besides X-rays is their galaxy populations, and the range of types and masses of galaxies in clusters changes with time, possibly for a number of different physics reasons. We will improve our knowledge of the populations close to us (and so in the contemporary Universe) as a reference for comparisons with the populations in the new clusters. Theories tell us that the galaxies that we see cannot exist without some means of slowing the effects of gravity through some feedback process that stops gas collapsing into an over-massive object. It is conjectured that much of the feedback is due to phenomena occurring in a central supermassive black hole in galaxies, and we will study this process by looking at the X-ray signatures of strong gravity from these supermassive black holes (comparing them with the smaller holes known in our galaxy) and by looking at the processes by which energy emerges from the neighbourhoods of the black holes into their wider environments through jets and other outflows. We will also look back at the very most distant galaxies and clusters that we can study in detail, to see if we can understand the beginnings of the formation process.The final element of the work involves developing a crucial set of computer codes that we, and many other researchers, use to examine astronomical data. Centred on TOPCAT, these codes are publically-available and popular, but must be improved to keep pace with changing data and computing needs.