Astrophysics at Oxford 2019-2022

牛津大学的天体物理学研究是由具有普遍兴趣的研究人员进行的，涵盖了从行星到宇宙的尺度。我们积极参与现代物理学中许多最令人兴奋的问题。在行星现象的尺度上，我们寻求找到新的世界，并了解它们的大气在极端条件下的行为。有了行星大气层的知识，我们也许能够了解它的成分，以及它是如何进化的。行星研究人员对其他太阳系如何形成和随时间变化以及为什么它们与我们的太阳系如此不同感兴趣。黑洞研究是天体物理学最令人兴奋的领域之一。我们研究了黑洞在吸积周围物质时成长的湍流气体过程，并计算了当星系中心的大质量黑洞通过潮汐力撕裂恒星并吞噬碎片时可能观察到的情况。气体吸积可以在类星体或活动星系中产生壮观的烟花，或者在我们银河系的情况下几乎没有一个光点。牛津大学的研究人员测量了遥远星系中分子的辐射，以揭示中心黑洞及其周围环境的性质。我们致力于黑洞形成的前沿研究，跟踪中子星碎片碰撞并合并成黑洞的无线电波，并以此来了解这场非凡的宇宙灾难的物理学。在与我们自己的银河系相关的尺度上，我们非常详细地研究单个恒星的运动，利用这些结果来了解我们的银河系是如何形成和维持其结构的，以及一个巨大的看不见的暗物质光环是如何通过恒星的运动来揭示它的存在的。我们利用星系团环境的观测，大量的稀薄磁化气体加热到X射线温度，约束弦理论所提出的物质的基本性质。整个宇宙中星系的演化受到其环境的影响，而环境又受到星系反馈的影响。通过宇宙时间来解开这种星系耦合的细节是一项艰巨的任务。它需要分析大量的观测数据。我们保持着一个庞大的、活跃的研究小组，从星系形成的最高红移到现在的宇宙时间，在其所有范围内追求这个重大问题。有关宇宙时间内星星形成速率的问题，星系形态本身如何演变，邻居的存在是否会导致星系的自旋旋转对齐，中央黑洞如何发展，都在牛津大学进行调查。这涉及利用现有设施以及规划设计和执行与重大国际合作有关的关键文书。最大的尺度与CMB（宇宙微波背景辐射）有关。切除由我们自己的银河系造成的前景污染的过程非常困难，但却是必不可少的，这是由设计和建造C-BASS仪器的牛津团队领导的。这是我们的研究人员如何开发技术的一个例子，从非常敏感的数据中哄骗宇宙的深刻秘密。最初是什么微小的波动产生了星系和它们的大规模集群？对基本粒子的质量和对经典广义相对论的偏离可以施加什么限制？通过将来自普朗克等CMB仪器的信息与其他与星系团有关的数据集相结合，正在开发强大的新工具。

Astrophysical research at Oxford University is carried out by investigators with universal interests, spanning scales from planetary to cosmic. We are actively engaged with many of the most exciting questions of modern physics.On the scale of planetary phenomena, we seek to find new worlds and to understand how their atmospheres behave under extreme conditions. With knowledge of a planet's atmosphere, we may be able to learn something of its composition, and how it has evolved. Planetary researchers are interested in how other solar systems form and change with time, and why they seem to be so different from our own.The study of black holes is one of the most exciting areas of astrophysics. We investigate the turbulent gas processes by which black holes grow as they accrete surrounding material, and calculate what one might observe when massive black holes in the centres of galaxies rip apart stars by tidal forces and devour the debris. Gas accretion can produce spectacular fireworks in a quasar or active galaxy, or barely a blip in the case of our own Milky Way Galaxy. Oxford researchers measure the radiation from molecules in distant galaxies to reveal the properties of the central black holes and their surroundings. We pursue studies at the cutting edge of black hole formation, tracking the radio waves emerging from the debris of neutron stars that have collided and coalesced into a black hole, and using this to understand the physics of this remarkable cosmic catastrophe.On scales associated with our own Milky Way Galaxy, we study the motion of individual stars in great detail, using the results to understand how our Galaxy formed and maintains its structure, and how a great halo of invisible dark matter, which keeps the Galaxy bound, betrays its presence through the motions of the stars. We exploit observations of the galactic cluster environment, vast volumes filled with rarified magnetised gas heated to X-ray temperatures, to constrain the fundamental properties of matter suggested by string theory. The evolution of galaxies throughout the Universe is influenced by their environment, which is in turn impacted by galactic feedback. To unravel the details of this galactic coupling through cosmic time is an enormous task. It requires the analysis of vast amounts of observational data. We maintain a large, active group of researchers pursuing this grand problem in all of its scope, from the highest redshifts at which galaxies form up to present cosmic times. Questions pertaining to the rate of star formation throughout cosmic time, to how galactic morphology may itself evolve, to whether the presence of neighbours causes galaxies' spin rotations to align, to how central black holes develop, are all being investigated at Oxford. This involves the use of current facilities as well as planning the design and implementation of key instruments to be associated with major international collaborations. The largest scales of all are associated with the CMB, the cosmic microwave background. The exquisitely difficult but essential process of excising the foreground contamination caused by our own Galaxy is led by the Oxford team designing and building the C-BASS instrument. This is an example of how our researchers are developing techniques to coax profound secrets of the Universe from very sensitive data. What were the initial tiny fluctuations that gave rise to galaxies and their larger scale clusters? What constraints can be placed on the masses of elementary particles and deviations from classical general relativity? By combining information from CMB instruments like Planck with other data sets related to galaxy clustering, powerful new tools are being developed.