Imperial College Astrophysics Consolidated Grant 2016-2019

我们在天体物理学的研究包括宇宙学（宇宙的研究），最遥远的星系，系外行星（其他恒星周围的行星）和引力波（爱因斯坦预测的时空扭曲，但迄今尚未检测到）的领域。这项工作将有助于回答一些可能提出的最大问题，包括：我们能在太阳系外找到生命的迹象吗？宇宙的命运是什么？我们的工作包括理论和观察的结合。我们使用最先进的设备，比如普朗克和赫歇尔卫星，（将于2015年发射），我们还开发了理论和技术，这将导致下一代卫星和实验的发展建议。我们对宇宙性质的理解在过去20年中发生了深刻的变化，因为人们发现宇宙正在加速膨胀，作为实验，主要是那些观测宇宙微波背景的实验，已经允许精确测量描述宇宙的参数--普通物质（原子）、暗物质和暗能量的比例，以及当前的膨胀率。暗物质因引力而聚集，其质量是普通物质的5倍，但它的组成尚不清楚。更大的谜团是暗能量，它导致了宇宙的加速，并主导着质能收支。我们在宇宙学方面的工作采取了不同的方法来回答这些问题。但我们研究的共同主题是理解进步将通过更精确地测量数量（宇宙学距离，膨胀率）的改进实验来实现。这些实验依赖于更好的技术（例如，测量宇宙微波背景的偏振），更好地了解正在研究的物理学（超新星的性质用于测量宇宙学距离），以及更好的数据分析技术，提高结果的精度和准确性（将贝叶斯形式主义严格应用于复杂的大型数据集）。在过去的20年里，我们银河系中许多离我们最近的恒星周围的行星，以及其他恒星系统的第一个特征。如果最终的目标是在其他行星上发现生命，这将通过理解不同类型的行星（岩石/气体，大/小）如何在不同类型的星星（老/年轻，活跃/不活跃，热/冷）周围以不同的径向距离形成，以及星星如何在其生命周期中影响其行星上的条件来实现。我们在这一领域的工作包括理解行星形成机制的理论工作，以及对恒星可变性的更深入理解，以及这如何微妙地影响行星大气层的测量（可能导致错误的结论），以及影响行星的可居住性。爱因斯坦1915年广义相对论的一个结论，该理论描述了由于质量导致的时空弯曲，是那些正在加速的物体以引力波的形式辐射能量，以光速传播曲率变化的信号。引力波还没有被探测到，但它们的探测是物理学的伟大目标之一。这种影响是极其微妙的，因此需要在远离振动源和地球影响的空间进行测量。我们对引力波的研究集中在为计划中的欧洲航天局使命LISA（预计不会在2030年之前发射）的技术开发做出贡献，以及分析将于2015年发射的LISA探路者使命的数据，该任务将测试这些技术的原型。

Our research in Astrophysics includes theareas of cosmology (the study of the Universe), the most distantgalaxies, exoplanets (planets around other stars), and gravitationalwaves (distortion of space-time predicted by Einstein but so far notdetected). This work will make a contribution towards answering someof the greatest questions that can be posed, including: can we findsigns of life outside the solar system? and what is the fate of theUniverse? Our work involves a combination of theory andobservations. We use cutting-edge facilities such as the Planck andHerschel satellites, and LISA Pathfinder (to be launched in 2015), andwe also develop the theory and technology that will lead to proposals for thedevelopment of the next generation of satellites and experiments.Our understanding of the nature of the Universe has changed profoundlyover the past 20 years, since it was discovered that the expansion ofthe Universe is accelerating, and as experiments, primarily thoseobserving the cosmic microwave background, have allowed the accuratemeasurement of the parameters describing the Universe - theproportions of ordinary matter (atoms), dark matter, and dark energy,and the current rate of expansion. Dark matter clumps gravitationallyand outweighs ordinary matter by a factor 5, but what it consists ofis unknown. The even greater mystery is dark energy, which is causingthe acceleration of the Universe, and which dominates the mass-energybudget. Our work in cosmology takes different approaches to answeringthese problems. But the common theme in our research is theunderstanding that advances will come through improved experimentsthat measure quantities (cosmological distances, the rate ofexpansion) more accurately. The experiments rely on better technology(e.g. measurements of polarisation of the cosmic microwavebackground), better understanding of the physics under study (theproperties of supernovae used to measure cosmological distances), andbetter data analysis techniques that improve the precision andaccuracy of the results (applying rigorously the Bayesian formalism tocomplex large datasets).No less profound for humankind has been the discovery, again over thepast 20 years, of planets around many of the nearest stars in ourgalaxy, and the first characterisation of other stellarsystems. If the ultimate goal is to discover life on other planetsthis will be achieved through successive advances in understandinghow different types of planet (rocky/gaseous, large/small) form arounddifferent types of star (old/young, active/inactive, hot/cool) atdifferent radial separations, and of how the star over its lifetimecan affect the conditions on its planets. Our work in this areaincludes theoretical work to understand the mechanisms by whichplanets form, as well as developing a deeper understanding of stellarvariability and how this can subtly bias measurements of theatmospheres of planets (possibly leading to eroneous conclusions), aswell as influence the habitability of planets.A consequence of Einstein's 1915 theory of general relativity, whichdescribes the curvature of space-time due to mass, is that massiveobjects undergoing acceleration radiate energy in the form ofgravitational waves, propagating the signal of the change of curvatureat the speed of light. Gravitational waves have yet to be detected,but their detection is one of the great goals of physics. The effectis extremely subtle, so measurements in space away from sources ofvibration and the influence of the Earth are called for. Our researchon gravitational waves centres on contributing to the development oftechnologies for use in the planned European Space Agency mission LISA(not expected to launch before 2030), and analysis of data from theLISA Pathfinder mission, to be launched in 2015, that will testprototypes of these technologies.