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.

Astronomy inspires and fascinates the specialist and non-specialist alike. Many Department members, representing a wide variety of interests, give public talks at all levels, including primary schools, high schools, policy makers, and industry. These activities are not merely confined to the UK, they extend into continental Europe and developing countries. We also hold hugely popular Stargazing Events for the public throughout the year, and engage the public more deeply in our activities with programmes like the Citizen Science Projects Zooniverse, MoonZoo and Planet Hunters. Enabling schools in developing countries to carry out astronomy research via the global Jet Watch Project is a particularly far-reaching activity.
In addition to our educational efforts, our research findings make significant contributions in areas such as turbulence, weak signal detection, and heating and energy transfer in plasmas. These contributions are all important in making progress towards the solutions of societal problems. The challenge for us as astrophysicists is to understand the physical phenomena that are present under the extreme conditions found throughout the Universe, conditions that cannot be replicated in the laboratory. In meeting this challenge, we are able to understand and explore the laws of physics in environments that would not be remotely plausible or affordable here on Earth.
A case in point is that of plasma physics, in which progress in fusion is so crucial to the enduring supply of safe energy for the inhabitants of this planet. The sorts of problems frequently encountered in the development of fusion devices (e.g. anomalous energy transport and instabilities) have precise analogues in the study of astrophysical plasmas. We have close intellectual ties and many exchange visits with UKAEA Culham in order to expedite this knowledge exchange.
Climate change too, is of profound importance for the future yet it can be difficult for the non-specialist to understand the important influences and consequences and is hindered by confused representations in the popular press. Astronomy however is neutral and non-partisan and so understanding gained from outer space makes it easier to comprehend and bring perspective to the problems we have to grapple with on Earth. Case studies of exo-planets can make the crucial findings more accessible than only studies of our own planet can.
The state-of-the-art instrumentation with which we detect the most sensitive primordial signals from the early Universe drives significant advancements in industrial development. The research and development in, for example, our C-BASS project is feeding back into next-generation instrumentation such as the SKA radio telescope and industry itself. With further enhancements to our instrumentation programmes will come stimulation to industry in areas such as communications, microwave receivers, optics, interferometry, digital signal processing and remote sensing.
Our computational work has many positive consequences in Big Data, software development as well as complex computation on GPUs (the graphics cards within even modest desktop computers that have been developed by the games industry) that we are exploiting for big data handling and computation.