Astrophysics at Oxford 2016-2019

牛津大学的天体物理学研究是由具有广泛兴趣的研究人员进行的，涵盖从行星到宇宙的尺度。我们的活动是普遍的，在这个词的每一个意义上。我们积极参与现代物理学中许多最令人兴奋的问题。在熟悉的行星现象的尺度上，我们试图了解遥远世界的海洋，大气和气候模式的行为。我们正在研究其他太阳系是如何形成和演化的，以及为什么它们看起来与我们的太阳系如此不同。恒星是我们学科的历史主食。我们正在研究双星合并的过程，以及当其中一颗恒星是黑洞时，圆盘和巨大的喷流是如何从吸积、X射线发射气体中形成的。在与银河系相关的更大尺度上，我们非常详细地研究了单个恒星的组合运动，利用结果来了解银河系如何保持其结构，以及巨大的不可见暗物质晕如何通过可见发光物质的运动间接揭示其存在。星系中的气体会吸积到中心黑洞上，其后果从类星体和活动星系核的壮观到我们银河系的轻微波动。牛津大学的研究人员研究银河系中心，以了解其详细的物理学，并探测遥远星系中的气体分子，以揭示黑洞在其中心区域的性质。虽然形成恒星的气体最初非常冷，但星系中的大部分气体非常热且稀释。这些完全电离的空间等离子体与磁场强烈耦合，表现出非常不寻常和复杂的行为，其中许多方面根本不了解。牛津大学的研究人员试图了解粒子如何在等离子体冲击波中加速到巨大的能量，并计算质子和电子是否相互作用并相互加热，当它们是吸积流的一部分时。这些问题对于我们理解动力论的基本过程至关重要，其意义远远超出了天体物理学的范围。星系的形成和演化受到其环境的影响，而环境又受到星系本身存在的极大影响。要解开整个宇宙时间的细节是一项艰巨的任务，需要获取和分析大量的观测数据。牛津天体物理学保持着一个庞大而活跃的研究小组，他们在所有的范围内追求这个宏大的问题，从星系形成时的最高红移，一直到现在的宇宙时代。有关星星形成的速度，星系形态本身如何随时间变化，邻居的存在是否会导致自旋对齐，中央黑洞如何发展的问题，都在牛津大学进行研究。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。从我们自己的银河系（包括极化和非极化）中切除前景污染的过程非常困难但必不可少，由开发C-BASS仪器的牛津团队领导。牛津大学的研究人员正在开发一种技术，可以从非常敏感的数据中骗取宇宙的深刻秘密。最初是什么微小的波动产生了星系和它们的大规模集群？对基本粒子的质量或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 widespread interests, spanning scales from planetary to cosmic. Our activities are universal, in every sense of this word. We are actively engaged with many of the most exciting questions of modern physics. On the familiar scale of planetary phenomena, we seek to understand how the oceans, atmospheres and climate patterns of distant worlds behave. We are investigating how other solar systems form and evolve, and why they seem to be so different from our own.Stars are the historical staple of our discipline. We are investigating the processes by which binary stars merge, and how discs and great jets form from accreting, X-ray emitting gas when one of the stars is a black hole. On larger scales associated with the Milky Way Galaxy, we study the combined motions of individual stars in great detail, using the results to understand how the Galaxy maintains its structure, and how a great halo of invisible dark matter reveals its presence indirectly through the motions of visible luminous matter. Gas in galaxies accretes onto central black holes, with consequences that range from spectacular in the case of quasars and active galactic nuclei, to barely a blip in the case of our own Galaxy. Oxford researchers study the Galactic Centre to understand its detailed physics, and probe gas molecules in distant galaxies to reveal the properties of the black holes harboured in their own central regions. While the gas that forms stars is initially very cool, much of the gas in galaxies is very hot and dilute. These completely ionised space plasmas, which couple strongly to magnetic fields, exhibit very unusual and complex behaviour, many aspects of which are not at all understood. Oxford researchers seek to understand how particles are accelerated to enormous energies in plasma shock waves, and in calculating whether protons and electrons interact and mutually heat one another when they are part of an accretion flow. These are problems that are critical to our understanding of fundamental processes of kinetic theory, whose significance extends well beyond the boundary of astrophysics. The formation and evolution of galaxies is influenced by their environment, which is in turn greatly impacted by the presence of the galaxies themselves. To unravel the details of this throughout cosmic time is an enormous task, requiring the acquisition and analysis of vast amounts of observational data. Oxford Astrophysics maintains a large, active group of researchers pursuing this grand problem in all of its scope, from the highest redshifts at which galaxies form, down through present cosmic times. Questions pertaining to the rate of star formation, to how galaxy morphology itself may change with time, to whether the presence of neighbours causes spin alignment, to how the central black hole develops, 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 from our own Galaxy (both polarised and unpolarised) is led by the Oxford team developing the C-BASS instrument. Oxford 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 or on 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.