Research in Theoretical Astronomy 2009-2014

The Institute of Astronomy, Cambridge, is one of the worlds leading research Institutes in Astronomy. It comprises 19 academic staff, 51 postdoctoral research assistants and 52 PhD students, about half of whom work on theoretical astronomy. This grant application is asking for a renewal of the main theoretical rolling grant at the IoA. Over the next five years we will pursue a broad range of theoretical research on the following problems: (i) The Planck satellite is a third generation space satellite dedicated to measuring the temperature and polarization anisotropies in the cosmic microwave background. Planck is scheduled for launch at the end of 2008, some 15 years after it was first proposed to ESA. The years covered by the grant coincide with the peak period for the scientific exploitation of this satellite. PDRA support is requested to work with the Co-Investigators on core science projects. In particular, we are responsible for leading the key analysis of cosmological parameters from Planck and wish to investigate constraints on models of cosmic inflation. Cambridge has a leading role in the Clover polarization experiment and we wish to involve PDRAs in the scientific interpretation of that experiment. (ii) The cosmic microwave background radiation provides us with a picture of the Universe when it was 400,000 years old. At that time, the Universe was filled with a near uniform mixture of hydrogen , helium, dark matter and radiation. We will investigate how the first non-linear structures emerged from this stochastic background. Over the grant period the main emphasis of the research will be to perform hydrodynamic simulations including radiative transfer to model the thermal state of the intergalactic medium and spatially extended Lyalpha emission. We will also extend previous work on the matter power spectrum from the Ly alpha forest to constrain neutrino masses, in combination with data from Planck. (iii) The discovery of large numbers of extrasolar planets has led to enormous interest in theoretical work on the formation of planets. Over the grant period we will pursue a research programme building on expertise in protoplanetary and debris disk evolution. The work will be centred on linking the protoplanetary phase, when discs were gas rich and possible sites of ongoing gaseous planet formation, through to the debris disc phase, when discs were gas poor, dusty structures, with planetesimal bels as possible sites for terrestrial planet formation. (iv) Accretion discs are present in a wide variety of astronomical systems . In particular, accretion onto compact objects such as black holes, neutron stars and white dwarfs produce observational signatures that provide the main scientific justification for X-ray satellites and gravitational wave detectors. Magnetic fields are central to understanding the evolution of accretion discs. We will perform state-of-the-art numerical simulations of magnetised accretion discs to understand their role in accretion disc dynamics and to compute observational signatures. (v) Understanding stellar evolution is essential for the interpretation of all astrophysical systems, from stars in our own Galaxy to the formation of the first non-linear structures in the Universe. Over the next five years we will develop improved models of massive stars as the progenitors of supernovae and gamma-ray bursts. We will also develop fully three-dimensional numerical models of stellar evolution in binary systems, in collaboration with colleagues at Livermore. (vi) Finally, we will pursue two research themes to understand feedback processes in the cores of clusters of galaxies. We will investigate the physics of `emission line filaments', which are still not understood and we will use large numerical simulations to assess the impact of baryonic physics on the use of clusters as cosmological probes (e.g. testing the nature of dark energy.