Sean Febuary completed his PhD in Applied Mathematics at the University of Cape Town.
Brief description of his work: The growth of cosmic structure (e.g. galaxies,
clusters thereof) is poorly understood in inhomogeneous cosmological
models. Such models were originally proposed in the literature as an
attempt to explain observations (e.g. distances to type Ia supernova)
without dark energy. In this work, we solved - for the first time - the
full set of coupled partial differential equations that describe the
evolution of linear perturbations about a large spherically symmetric
underdense region of spacetime (i.e. a void). We showed that the
evolution of the density
contrast is well approximated by the previously studied decoupled
evolution only on very large scales. However, the evolution of the
gravitational potentials within the void is inaccurate at more than the
10% level, and is even worse on small scales.
His paper can be found at http://iopscience.iop.org/0264-9381/31/17/175008/ or Evolution of linear perturbations in spherically symmetric dust spacetime
Computation work was delivered by the University of Cape Town HPC Facilities and the eResearch Center.
