Towards a more perfect wind braking model F. F. Kou (寇菲菲) Supervisor: H. Tong (仝号) Cooperator：Z. W. Ou (区子维) Xinjiang Astronomical observatory, CAS 2015.07.05

Outline Outline Introduction The pulsar wind model Developments and applications Particle density Braking index evolution Long-term evolution of the pulsar when considering pulsar death Variable timing behavior in the pulsar wind model Discussions and conclusions References

Introduction

Traditional magneto-dipole radiation (magnetic dipole rotating in vacuum): (Shapiro & Teukolsky 1983) Braking index expected in this model is 3.

Pulsar wind model (Xu & Qiao 2001)  

Braking index in the wind braking model: Xu & Qiao 2001 Potential drop of the acceleration gap The maximum potential drop for a rotating dipole.

The wind braking magnetar (Tong et al. 2013).   The wind braking magnetar (Tong et al. 2013). Wind braking intermittent pulsar (Li et al. 2014). ……………

Development and application The accelerated primary particle density should be larger than the Goldreich-Julian particle density. Braking index evolution in the pulsar wind model Long-term evolution of pulsars when considering pulsar death. Variable particle density result in the variable timing behavior

1.Particle density   For the Crab pulsar, particle density should be 100~10^4 times Goldreich-Julian charge density

2.Braking index evolution in the wind braking model Braking index evolves from 3 to 1 (6/7) magneto-dipole radiation to particle wind

3.Long-term evolution of pulsars (pulsar death) why is the pulsar death essential ? A pulsar death when (Ruderman & Sutherland 1975)

The effect of pulsar death Contopoulos & Spitkovsky 2006

Crab evolution in the VGCR model

4.Variable timing behaviors in the pulsar wind model 36% increase in the spin-down rate

Braking index of the Crab pulsar

a. Different particle density result in variable spin down rate  

b. A changing particle density will result in variable timing behavior For the Crab pulsar: n=2.3< 2.51   For PSR J1846-0258: n=2.19< 2.65  

Discussions  

Conclusions In the pulsar wind model, the pulsar is braked to spin down by the combined effect of magnetic field and particle density. Braking index expected is between 1 (model dependent) and 3. Considering pulsar death, pulsars will not evolve towards the cluster of magnetars but downwards the death valley. Different particle density result in variable spin down rate. An increasing particle density results in a lower braking index. The pulsar wind model can be applied to other pulsars or magnetars. ……

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