Consolidated grant for interim support of astronomy at Oxford

The proposal addresses three major themes in astronomy - to understand the origin of the Universe and the formation of galaxies, and to discover planetary systems similar to our own.

All that we can see is thought to have emerged 14 gigayears ago when gravity was briefly an intensely repulsive force and blasted outwards a small region of space. After this "Big Bang", the Universe was hot, so it was full of thermal radiation. The density of this radiation was almost but not quite uniform, and the galaxies we see now owe their existence to small inhomogeneities in it. However, the clearest tracer of the primordial inhomogeneities is not the distribution of galaxies but the residual radiation field of the Big Bang, which can still be detected at radio frequencies. Consequently, for several decades astronomers have sought to measure this background radiation with ever greater precision from both the ground and space. The work proposed here is directed at improving measurements from the ground at low frequencies, where most of the detected radiation arises in our Galaxy rather than being relic radiation. Correct interpretation of data currently been taken from space by the Planck satellite requires the better knowledge of emission by our Galaxy that these ground-based measurements will provide. New technologies will also be developed to detect the earliest star formation.

Astronomers have a theory of how galaxies formed. Detailed examination of our own Galaxy provides the strictest test of this theory, so major observational resources are being devoted to minutely examine of the Galaxy. Unfortunately, all observations of our Galaxy are strongly biased by our location within the system - what is near us features largely in the data, while distant objects of greater significance are overlooked. Moreover, we use different instruments, from radio telescopes to the largest optical spectrometers and special space-borne telescopes that measure the positions of stars, to measure different aspects of the Galaxy. To bring all these data data together and to understand the impact of biases on the data we need dynamical models of our Galaxy. This proposal is both to continue development of such models and to develop a new approach to fitting models to data. For the moment the models are being fitted to data from several ground-based survey programs, but towards the end of the decade data will become available from the European Space Agency's "Cornerstone Mission" Gaia, and it is vital that powerful modelling machinery is in place and thoroughly tested before then.

In the last fifteen years astronomers have discovered several hundred planetary systems. The first - the easiest to detect - were very unlike the Solar System: they contained a Jupiter-like planet moving on an orbit like that of Mercury, and they revolutionised our theory of how planetary systems form. As the palette of available detection methods expands, so does the diversity of the systems being uncovered. The current consensus is that most of these systems probably formed in much the same way as the Solar System, but evolved differently in their early years. However, the theory is difficult, and its results uncertain. Therefore, the fascinating question of whether the Solar System is common or rare is best addressed by making an inventory of as many planetary systems as we can. This proposal is to fund continued work on this project. The brightnesses of thousands of stars are monitored with exquisite precision by satellites to look for tiny dips, which occur when a planet passes in front of its host star. By paying careful attention to the impact of noise, these `transits' can be used not only to discover new planets - including
ones resembling the Earth - but also to study the structure and composition of their atmospheres.

The general public is very much interested in origins, and the three themes constitute work that probes the origin of the Universe, the origin of the Galaxy, and the origin of the Solar System. All four investigators regularly give talks to lay audiences on their work. These activities stimulate interest in science and technology, particularly amongst young people.

In addition to this cultural impact, Theme 2 (experimental cosmology) will have commercial and technological impact through the development of both more sensitive and cost-effective radio receivers and more energy-efficient cryogenics. The latter aspects have drawn two industrial partners into the project, both of whom expect to make commercial gain from their involvement in this research.