Experimental radio cosmology at Oxford

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Our understanding of the universe has been transformed over the past 15 years as a result of the detection of the fluctuations in the Cosmic Microwave Background (CMB). These fluctuations result from tiny variations in the density of the primordial cosmic fluid when the universe was a tiny fraction of a second old. These were blown up to astronomical size by an extremely rapid expansion of the universe which lasted a minute fraction of a second; a phenomenon that astronomers call 'inflation'. A large number of instruments have been built to characterize the spatial distribution of these anisotropies by measuring their magnitude as a function of angular scale (their `power spectrum'). These measurements are very important because they tell us a lot about the evolution of the universe and because the anisotropies contain the code the led to the present structure in the universe. Members of the Experimental Cosmology group at Oxford have taken a leading role in cosmology instruments such as CAT, VSA and CBI. These instruments, and others, most notably the NASA space telescope WMAP, have revealed an incredible amount of accurate information, such as that the universe has a flat geometry, its age is 13.7 billion years and that 94% of the substance in the universe is not matter as we know it, but is a combination of a new form of matter called 'dark matter', and an even more mysterious form of dark energy. Is this then the end of the story then? On the contrary, the knowledge we have gained in the last 15 years induces us to seek answers to even more fundamental questions in physics and astronomy. Dark matter is a puzzle since we cannot detect it directly, but we can at least observe its gravitational impact clearly. Dark energy however is a lot more bizarre since it causes the expansion of the universe to accelerate rather than to slow down. Is this really true or is there an alternative explanation that reconciles all our observations? Can we confirm categorically that inflation really occurred and if so at what energy scale? These are the challenges of the next generation of cosmology instruments and this STFC grant will allow Oxford to make major contributions to these exciting developments. Our work will feed into the next cosmology developments in several ways. We take part in new national and international cosmology projects that are aiming to be 10 times more sensitive than any instrument ever built. These instruments will be able to detect extremely weak signals such as the CMB polarization that hold as much information as the CMB anisotropies, thereby allowing us to build a complete picture of the evolution of the universe. Our team includes astronomers who are experts in instrument design and construction and also in observation and data analysis. We also build our own small-scale instrument to investigate specific effects that feed into the general picture, and finally we develop the basic research in technology and astrophysics that supports the above mentioned activities. The support that we have requested in this application falls directly into these categories. We requested support for post-doctoral research scientists to analyse the astronomical data that will stream from instruments that we are working hard to build. We are also asking for effort to help us develop the state of the art technology that is required for building these instruments and finally we are asking for the hardware that will allow us develop and test this technology in our laboratories. It is an exciting programme that links theory, astronomical observation and experimental physics using the tremendous potential of bright young scientist to help us understand the world around us.