Imperial College Astrophysics Consolidated Grant 2019 - 2022

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，最近首次观察到）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、观察和实验室工作的结合。我们使用最先进的设备，如普朗克和赫歇尔卫星，以及未来的欧几里得卫星、平方公里阵列和大型综合巡天望远镜。我们还开发理论，这将导致下一代卫星和实验的发展建议。此外，我们还在实验室中测量不同原子的基本性质，以便与恒星中不同元素的观测结果进行比较。在过去的20年里，我们对宇宙性质的理解发生了深刻的变化，因为我们发现宇宙的膨胀正在加速，作为实验，主要是那些观察宇宙微波背景辐射的实验，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（用于测量宇宙学距离的超新星的性质），以及更好的数据分析技术，提高了结果的精度和准确性。对人类来说，同样意义深远的是，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）周围以不同的传统距离形成，以及星星在其一生中如何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论工作，以了解行星形成的机制，以及对恒星变化的更深入理解，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）。爱因斯坦1915年广义相对论的一个结论，它描述了由于质量导致的时空弯曲，是所有加速的物体都以引力波的形式辐射能量，以光速传播。经过数十年的开发工作，为了提高仪器的灵敏度，Advanced LIGO联盟终于在2015年9月探测到了引力波。这一发现开辟了探索宇宙的全新途径，提供了丰富的新可能性。我们在这一领域的兴趣是超前思考，通过发展什么可能是可检测的理论，预测如何解释新的测量，并指导下一代仪器的发展。

Our research in Astrophysics includes the areas of cosmology (thestudy of the Universe), the most distant galaxies, exoplanets (planetsaround other stars), and gravitational waves (distortion of space-timepredicted by Einstein, and recently observed for the first time). Thiswork will make a contribution towards answering some of the greatestquestions that can be posed, including: can we find signs of lifeoutside the solar system? and what is the fate of the Universe? Ourwork involves a combination of theory, observations, and laboratory work. We usecutting-edge facilities such as the Planck and Herschel satellites,and in the future the Euclid satellite, the Square Kilometre Array,and the Large Synoptic Survey Telescope. We also develop thetheory that will lead to proposals for the development of the nextgeneration of satellites and experiments. In addition we measure inthe laboratory fundamental properties of different atoms, forcomparison against observations of the different elements in stars.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.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 stellar systems. Ifthe ultimate goal is to discover life on other planets this will beachieved through successive advances in understanding how differenttypes of planet (rocky/gaseous, large/small) form around differenttypes of star (old/young, active/inactive, hot/cool) at differentradial separations, and of how the star over its lifetime can affectthe conditions on its planets. Our work in this area includestheoretical work to understand the mechanisms by which planets form,as well as developing a deeper understanding of stellar variabilityand how this can subtly bias measurements of the atmospheres ofplanets (possibly leading to erroneous conclusions).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, propagatingat the speed of light. After decades of development work, toimprove the sensitivity of the instruments, gravitational waves werefinally detected in September 2015 by the Advanced LIGO consortium.This discovery opens up an entirely new way of exploring the universe,offering rich new possibilities. Our interest in this field is inthinking ahead, by developing the theory of what might be detectable,to anticipate how to interpret new measurements, and to guide thedevelopment of the next generation of instruments.