Imperial College Astrophysics Consolidated Grant 2016-2019

我们在天体物理学方面的研究包括宇宙学(宇宙研究)、最遥远的星系、系外行星(围绕其他恒星的行星)和引力波(爱因斯坦预测的时空扭曲，但到目前为止还没有发现)。这项工作将有助于回答人们可能提出的一些最大的问题，包括：我们能否找到太阳系外的生命迹象？宇宙的命运又是什么呢？我们的工作是理论和观察相结合的。我们使用尖端设备，如普朗克和赫歇尔卫星，以及丽莎探路者(将于2015年发射)，我们还开发了理论和技术，将导致下一代卫星和实验的发展建议。在过去的20年里，我们对宇宙本质的理解已经发生了深刻的变化，因为我们发现宇宙正在加速膨胀，作为实验，主要是观察宇宙微波背景，使得能够准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，以及当前的膨胀速度。暗物质在引力作用下聚集，重量比普通物质大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，并主导着质量能量预算。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认识到，进步将通过更准确地测量数量(宇宙距离、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)，更好地理解正在研究的物理(用于测量宇宙距离的超新星的性质)，以及更好的数据分析技术来提高结果的精确度和准确性(严格地将贝叶斯形式应用于复杂的大型数据集)。对人类来说，同样深刻的是，在过去20年里，围绕我们银河系中许多最近的恒星发现了行星，并首次描述了其他恒星系统的特征。如果最终目标是发现其他行星上的生命，这将通过以下方面的不断进步来实现：了解不同类型的行星(岩石/气体、大/小)是如何在不同的径向分离的不同类型的恒星(老/年轻、活跃/不活跃、热/冷)周围形成的，以及恒星在其整个生命周期中如何影响其行星上的条件。我们在这一领域的工作包括理论工作，以了解行星形成的机制，以及对恒星可变性的深入理解，以及这如何微妙地影响对行星大气层的测量(可能导致错误的结论)，并影响行星的宜居性。爱因斯坦1915年的广义相对论描述了由于质量造成的时空曲率，其结果是，正在加速的大质量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。引力波尚未被探测到，但探测引力波是物理学的伟大目标之一。这种影响是非常微妙的，因此需要在太空中远离振动源和地球的影响进行测量。我们对引力波的研究集中在促进开发用于计划中的欧洲航天局LISA任务(预计2030年前不会发射)的技术，以及对将于2015年发射的LISA探路者任务的数据进行分析，以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.