The interplay between astrophysics and particle physics is at the heart of research at Oxford; spanning from the very theoretical to the experimental and observational, our work addresses some of the outstanding problems of modern physics.
On the theoretical front, members of the physics department in the Beecroft Institute of Particle Astrophysics and Cosmology and in the Rudolf Peierls Centre for Theoretical Physics subdepartment lead the way in trying to understand the problem of dark matter, what it might be, how it affects the large-scale structure of the Universe. Allied to that is our expertise in constructing some of the most detailed simulations to date of the large-scale structure which can be used to understand galaxies themselves, how they formed and how the evolved over cosmic history.
The problem of dark energy, and how it affects the expansion of the Universe, is a pressing one. Our researchers are actively trying to devise its origin as well as examine how it bears on our understanding of the General Theory of Relativity and there is a particular interest in gravitational waves and numerical relativity. Looking further back in time, researchers at Oxford have been active in proposing models for and exploring the physics of the early universe, from a possible early period of inflation to, more generally, the dynamics of particles and fields during the hot primordial soup.
Cosmic microwave background
One of the goals of modern cosmology is to map the Universe on a range of wavelengths, angular scales and redshifts. Our group is playing a leading role in current and future cosmic microwave background experiments such as the Atacama Cosmology Telescope (ACT), CBASS, the Simons Observatory and its successors. It has also spearheaded the detailed characterisation of the cosmic web through surveys targeting gravitational weak lensing and galaxy clustering with CFHTLenS, KIDS and, looking forward, the Euclid Satellite, the Rubin Observatory and the Square Kilometre Array.
At the highest photon energies, the gamma-ray astronomy group are members of H.E.S.S., the largest of the current generation of experiments in ground-based very-high-energy (VHE) astronomy. We have leading roles in defining the science case and in the design and construction of the next-generation VHE observatory, the Cherenkov Telescope Array. CTA will explore some of the most extreme regimes in the Universe, using high-energy gamma-rays as probes of astrophysical particle acceleration and beyond-standard-model physics.
We are leading the way in constructing instruments and experiments to look for some of the most elusive particles in the cosmos: we have been heavily involved in the SNO experiment, and its successor SNO+ based at Sudbury, Canada, which looks at neutrinos produced by the Sun. SNO won the 2015 Nobel prize for its ability to show how neutrinos are able to change between different families during their lifetime.
Even more elusive is dark matter and we have been working on some of the most powerful experiments to date. Researchers at Oxford are involved in the LUX-ZEPLIN experiment which is searching for particle dark matter using detector with seven tonnes of liquid Xenon housed in a chamber at the Sanford Underground Research Facility in South Dakota, US.