2026/06/30 by H. Tong
Physics and Astronomy · #astro-ph.HE
6 pages, accepted in RAA
arxiv created 2026/07/30 · arxiv updated 2026/07/31
The pulsar PSR B0540-69 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 will be smaller in the high spin-down state. 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 density. The braking index evolution of PSR B0540-69 is found to be in an exponential form. Its braking index 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 the particle acceleration mechanism in the pulsar magnetosphere. Finally, a phenomenological treatment of the wind braking model is presented in the appendix. It can simplify the applications of wind braking model to pulsar braking index, intermittent pulsars and PSR B0540-69.