H. Tong

The pulsar PSR B0450-69 has both a braking index measurement and spin-down state change. After its spin-down state change, it shows an increasing braking index with time. Previously, it is pointed out that the spin-down state change may be caused by an enhanced particle wind. The prediction is that its braking index in the high spin-down state will be smaller. The current measured braking index is approaching the previous prediction. The transient variation of braking index may be due to a small varying part of the particle number density. The final braking index evolution is found to be in an exponential form. The braking index of PSR B0540-69 is expected to approach some steady value. Future braking index measurement may make clear the physics for the braking index evolution. It may also help to make test different particle acceleration potential in the pulsar magnetosphere. Finally, a phenomenological treatment of wind braking model of pulsars is presented. It can simplify the applications to pulsar braking index, intermittent pulsars and PSR B0540-69.