Research 2010

November 2010

Kostas Glampedakis, Nils Andersson, Ian Jones, Lars Samuelsson

A key issue in the physics of neutron stars is understanding the structure and evolution of their magnetic field. There is ample astrophysical motivation for carrying out research on this subject. For instance, the high-energy burst activity observed in the most strongly magnetized neutron stars, the systems known as magnetars, is believed to be powered by the magnetic field itself. It is also suspected that the slowly evolving magnetic field in the interior of neutron stars provides the poorly understood evolutionary link between different subgroups of the known neutron star population.

Our recent work has been focussed on the effect of superfluidity and superconductivity (properties acquired by the bulk of neutron star matter soon after the star's birth) on the magneto-hydrodynamics of neutron stars.

April 2010

Christian Krüger, Erich Gaertig, Kostas Kokkotas

During the past few years, oscillations and instabilities of rapidly rotating stars have been studied both in a perturbative way by additionally fixing the spacetime and by solving the full set of the Einstein equations. A primary reason for these studies is the fact, that rapidly rotating stars can be destabilized due to the so-called CFS-instability; a secular instability that operates via a dissipative effect, the emission of gravitational waves. Most of these studies have been performed with configurations of rigidly rotating neutron stars. However, in order for the CFS-instability to be effective one typically needs very high rotation rates which are most likely to be found in young, newly born neutron stars. In this phase, they not only rotate fast but also differentially, i.e. the angular velocity is not constant throughout the star. In this study, we investigate the effect of various degrees of differential rotation on the frequencies of non-axisymmetric perturbations and its influence on the onset of the CFS-instability.

April 2010

Burkhard Zink, Oleg Korobkin, Erik Schnetter, Nikolaos Stergioulas

The Chandrasekhar-Friedman-Schutz instability in rapidly rotating, young neutron stars promises to be a substantial source of gravitational radiation, which may be observable from Earth in the near future. In this study, a fully general relativistic simulation code, THOR, is employed to determine the frequency spectrum of unstable modes of oscillation.