Warwick Astronomy and Astrophysics Consolidated Grant 2017-2020

宇宙中最猛烈的爆炸的动力是什么？什么样的星系拥有它们？它们与更普通的星系有什么关系？双星系统中的恒星是如何相互作用的？当这些恒星一起旋转时，我们能探测到爱因斯坦预言的时空中的微小涟漪吗？我们能探测到这些事件发出的光吗？其他恒星周围的行星是什么样的？有多少个？它们是用什么做的？这些问题的范围从我们银河系的近邻到可观测宇宙的最远处，都是沃里克天文学和天体物理学小组将要研究的问题。我们将通过地面和空间望远镜的综合观测、理论发展和计算密集型数值模拟来实现这一目标。尽管宇宙的大部分都在我们无法直接触及的地方，但我们对物理学的理解使我们能够推断出难以想象的温度、密度、速度和磁场。然而，就像最强大的计算机只能提前几天预测天气一样，控制天体的方程也可能非常复杂，难以求解，我们需要观察来指导我们。从我们的后院开始，20多年前，我们唯一知道的行星是我们太阳系的行星。今天，我们知道在其他恒星周围有1000多颗行星，其中许多与我们的近邻非常不同。沃里克是一个欧洲合作项目的领导机构，该项目对海王星大小的行星进行了新的调查。这项调查是基于行星阻挡来自恒星的光线时光线的减少。这些是发现的最有趣的行星，因为它们使我们能够测量行星的质量和大小。对于特定的质量，行星的大小取决于它的内部特性，这为探测距离地球数光年的行星内部提供了非凡的可能性。令人难以置信的是，还有一种更直接的方法：我们现在知道了一种被称为白矮星的致密死亡恒星，它们被行星建筑材料的尘埃盘所包围。当这些物质像雨点一样落在白矮星上时，它就会蒸发，这样我们就可以测量它的构成了。白矮星通常是高度稳定的，但很少，如果有足够的物质倾倒在它们身上，就像它们在双星系统中有一个伴星时一样，它们会通过不受控制的核聚变爆炸。这在几秒钟内将整个恒星撕裂，在这个过程中产生了已知的最明亮的爆炸之一，同时也产生了当今宇宙中大部分的铁。我们有兴趣了解这些罕见事件是如何发生的。这样的“超新星”是如此罕见，以至于我们必须在我们自己的星系之外寻找它们，而在那里可以看到更罕见和更奇特的灾难。所有爆炸中最亮的是伽马射线暴（grb），它很罕见，但非常明亮，在遥远的宇宙中可以看到超过100亿光年。值得注意的是，如此戏剧性的事件似乎有多种发生方式。我们的目标是了解其根本原因。令人惊讶的是，最强大的事件对我们的眼睛来说可能是非常模糊的：当一对黑洞相互绕轨道运行时，它们通过“引力波”的能量发射而螺旋进入，引力波是空间结构中的涟漪。物理学家们即将探测到这种现象，他们用奇特的激光和镜子来捕捉长度的微小扰动。我们想要“看到”这样的事件，这是一个艰巨的挑战，因为我们的引力波“眼睛”在确定天空中的位置方面很差，而且事件可能非常暗淡。超新星，grb和合并黑洞来自于星系中的恒星。为了理解它们，我们需要了解星系，它们是如何形成恒星的，以及它们在宇宙130亿年的历史中是如何演变的。

What powers the most violent explosions in the Universe? What kind of galaxies host them? How do they relate to more normal galaxies? How do stars interact with each other in binary systems? When such stars spiral together, can we detect the tiny ripples in space-time that Einstein predicted and can we detect any light from such events? What are planets around other stars like? How many are there? What are they made of? These questions, which range from near neighbours in our Galaxy to the furthest reaches of the observable Universe, are those that the Warwick Astronomy and Astrophysics group will investigate. We will do so with a mixture of observations using ground- and space-based telescopes, theoretical developments and computationally-intensive numerical modelling. Although most of the Universe lies far beyond our direct reach, our understanding of physics allows us to extrapolate into regimes of unimaginable temperatures, densities, velocities and magnetic fields. Nevertheless, just as the most powerful computers can only forecast the weather for a few days in advance, the equations governing celestial objects can be formidably complex to solve, and we need observations to guide us. Starting in our backyard, a little over 20 years ago, the only planets we knew about were the planets of our own Solar System. Today, we know of more than 1000 planets around other stars, many of them extraordinarily different from our near neighbours. Warwick is the lead institute in a European collaboration to implement a new survey for Neptune-sized planets. The survey is based upon the decrease of light as the planets blocks light from the star. These are the most interesting planets to find because they allow us to measure both the mass and size of the planet. For a particular mass, the size of a planet depends upon its interior properties, opening up the remarkable possibility of probing the interiors of planets light-years from Earth. Incredibly, there is a more direct method still: we now know of dense, dead stars called white dwarfs which are surrounded by dusty disks of planetary building materials. As this material rains down onto the white dwarf, it is vaporised, allowing us to measure what it is made of. White dwarfs are usually highly stable, but very rarely, if enough matter is dumped onto them as can occur when they have a nearby companion in a binary system, they explode through uncontrolled nuclear fusion. This tears the entire star apart within a few seconds, in the process producing one of the optically-brightest explosions known along with most of the iron in the present day Universe. We are interested in understanding how these rare events come about. Such "supernovae" are so rare that we have to look beyond our own Galaxy to find them, and that is where even rarer and more exotic cataclysms are seen. The brightest explosions of all are the Gamma Ray Bursts (GRBs), which are rare, but so bright that they can be seen more than 10 billion light-years away in the distant Universe. Remarkably for such dramatic events, there seem to be multiple ways for them to occur. We aim to understand their underlying cause. Surprisingly, the most powerful events of all may be very dim to our eyes: when a pair of black-holes orbits one another, they spiral-in because of the emission of energy through "gravitational waves", ripples in fabric of space. Physicists are on the verge of sensing these with exotic arrangements of lasers and mirrors designed to pick up tiny perturbations of length. We want to *see* such events, a tough challenge because our gravitational wave "eyes" are poor at pinning down locations on the sky and the events may be very dim. Supernovae, GRBs and merging black-holes come from stars residing in galaxies. To understand them, we need to understand galaxies, how they form stars and how they evolve over the 13 billion year history of the Universe.