Evidence for nonlinear and chaotic behaviour in pulsar spin-down rates Seminar

Our understanding of neutron star spin evolution took a dramatic twist a few years ago with the discovery of multiple spin-down rates for a sample of pulsars reported by Lyne et al. Following a brief review of these observations, and related results for the so-called intermittent pulsars, I will describe our study which searches for signs of nonlinear behaviour in the data which might indicate that the spin frequencies are governed by a low-dimensional strange attractor. For one pulsar in particular, B1828-11, we find that the spin-down states could be governed by such an attractor. The physical origin of this mechanism is still unclear. Suggestions for future work will also be given.