| Abstract |
This proposal is for an interim grant to support research in Theoretical Astrophysics and X-ray Astronomy at the Institute of Astronomy (IoA), as part of a transition to a fully consolidated IoA Astronomy grant proposal in 2012. The Theory theme addresses a wide range of astrophysical phenomena ranging from the origin of the Universe itself to the formation and evolution of galaxies, stars and planets. One of the main areas of investigation is cosmology. Members of the IoA are playing a leading role in the European Space Agency Planck mission, and will lead a definitive determination of the cosmological parameters including the age, size, dark matter, dark energy and baryonic contents of the Universe. Another project will carry out theoretical simulations and analysis of the subsequent evolution of cosmic structure during the epoch of reionisation, when the first stars and galaxies were formed. Star formation is another major focus of the grant, on scales ranging from galaxies, where the molecular clouds giving birth to stars are formed, to the formation of stars and star clusters within these molecular clouds. These investigations will combine state-of-the-art numerical simulations with analytical theory and a rich new set of multi-wavelength observations of nearby galaxies being obtained with the Herschel and Spitzer space observatories under IoA leadership. The understanding of planetary systems around stars and their formation is another goal of the Theory theme. One project will focus on modelling the properties of debris discs, discs of asteroids, cometary objects, and dust surrounding stars, using a complete IoA-led survey of nearby stars with the Herschel observatory (DEBRIS project). Another project is directed at modelling the evolution of the planetary orbits themselves in different stellar environments and stellar evolutionary stages. The final component of the Theoretical Astronomy theme is the modelling of binary star systems, and improving our understanding of how double star systems evolve when the component stars are immersed in a common envelope. This phase of evolution is important for understanding a wide range of observed stellar systems including cataclysmic variables, X-ray binaries, and the progenitors of supernovae, including the Type Ia supernovae which are used as cosmological standard candles. The second theme of the proposal is X-ray Astronomy. The research will exploit a large body of observations of galaxies, galaxy clusters, and Galactic X-ray binary systems being obtained by the X-ray group on the Chandra, XMM-Newton, Suzaku and ASTRO-H X-ray observatories to carry out three projects. One project will carry out measurements of the spin of black holes, both the supermassive black holes which power the enormous energy emissions from quasars and other active galactic nuclei, and the stellar-mass black holes in binary star systems. This work, based on spectroscopy of relativistically-broadened iron lines, will also provide insights into the accretion phenomena that power the systems. Another project will combine deep X-ray imaging and spectroscopy of the cores of galaxy clusters to study the physical conditions, turbulence, and acoustic waves and shocks in the intracluster medium, and constrain the physical nature of the feedback of radiative and mechanical energy from the galaxies in the cores of the cluster and the surrounding intergalactic gas in the clusters. A related project will combine these X-ray data with multi-wavelength measurements of the intergalactic filaments and other gas components in the clusters, to understand the feedback processes linking cooling of intergalactic gas into the central galaxies and the subsequent heating of the surroundings by the central galaxies and their embedded black holes. |
