PORTSMOUTH

• Research Training and Collaboration
• References

The Portsmouth team and organizational developments

The numerical relativity group at Portsmouth has been in operation for two years and the EU network activities are playing a central role in its research effort. Members of the Portsmouth Relativity and Cosmology group actively participating in the Network are: Marco Bruni (lecturer), Andrea Nerozzi (Ph.D. student), Philippos Papadopoulos (lecturer), Carlos Sopuerta (TMR Fellow). In addition, Virginia Re, Uli Sperhake and Florian Siebel (students from the Salerno, Southampton and Garching groups respectively), are working on joint projects with members of the group.

Andrea Nerozzi has joined the group as of September 1, 2001, using the EU network founding. A second student (Virginia Re) has joined the group through a Ph.D. program funded by the Italian government. Computer resources are available through the Relativity and Cosmology group in the form of a workstation and network facilities. A Nuffield grant has been used to purchase an entry level parallel processing facility dedicated to network science. A SRIF award to the Relativity and Cosmology group will provide both local and remote computing facilities which may be used, in part, for network science purposes.

Scientific highlights

The Portsmouth group is pursuing research in topics in numerical relativity, relativistic hydrodynamics and theoretical aspects of perturbation theory.

A powerful approach to numerical relativity is based on the use of light-like spacetime foliations. The successful, long term stable, evolution of vacuum dynamical spacetimes, using this approach, has focused current attention on astrophysical applications. In the first instance this required the development of appropriate hydrodynamical formulations and codes, which are now being applied in spherical and axisymmetric configurations. The approach is ideally adapted to systems of quasi-spherical topology and is characterised by simplicity and economy. Physical systems that have been explored so far include: dynamically accreting (growing) black holes [1], spherically symmetric neutron star spacetimes [2, 3, 6], axisymmetric neutron star spacetimes [7], and axisymmetric (vacuum) black hole spacetimes [5]. There is significant further scope for development and this direction will be pursued systematically in the future.

A new line of research is focusing on systems which are initially close to quasi-equilibrium. A judicious manipulation of the evolution equations permits the effective subtraction of balanced background terms, with significant increase in accuracy and stability. The concept has been illustrated in spherically symmetric neutron star configurations  [8], and a framework for more general spacetimes has been worked out [5].