Astrophysics at Oxford 2016-2019

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.