Radio Experimental Cosmology at Oxford

Just after the Big Bang, astronomers believe the Universe expanded rapidly during a period known as `cosmic inflation'. After a longer, gentler period, during which the gravitational pull of matter began gradually to slow down the expansion, the Universe now appears to have begun a second period of accelerated expansion. This recent expansion is driven by what astronomers call `dark energy'. Although astronomers believe all these things, no person on Earth understands either `cosmic inflation' or `dark energy'. This is a bit embarassing. Some reputable scientists believe that these mysterious concepts are signatures of totally new physics, or even of the presence of extra dimensions! Our research is aimed at designing, building and using telescopes to make observations of the Universe which will tell us more about both cosmic inflation and dark energy. Most explanations of cosmic inflation predict that whatever caused it should have left `fingerprints' of its activity in the form of ripples in space-time called gravitational waves. The effects of these ripples can be seen by looking at the polarization of the relic radiation from the Big Bang, the Cosmic Microwave Background. A major goal of our research is to build telescopes in Chile and Antartica which will be the first to find these fingerprints. These telescopes will be called QUIET and CLOVER. Unfortunately, these fingerprints must be found in a very messy Universe. Polarized radio emission from our own galaxy has to be understood incredibly well before we can `see through it', and find the fingerprints. We will be building a new instrument which we will take to radio telescopes in both the southern and northern hemispheres to help us find the cleanest bit of the galaxy to peer through with QUIET and CLOVER. This instrument will be called C-BASS. We will also keep working on the technologies that make our telescopes and instruments as sensitive as possible. We will be testing out new devices that use all sorts of clever quantum physics and digital processing techniques to measure signals from the Universe as cleanly and efficiently as possible. We hope one day to use these technologies to devise experiments that will tell us what dark energy is.