1. 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

2. 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

3. Introduction

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

7. Pulsar wind model (Xu & Qiao 2001)

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

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

10. 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

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

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

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

14. The effect of pulsar death
Contopoulos & Spitkovsky 2006

15. Crab evolution in the VGCR model

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

17. Braking index of the Crab pulsar

18. a. Different particle density result in variable spin down rate

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

20. Discussions

21. 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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Li, L., Tong, H., Yan, W. M., Yuan, J. P., Xu, R. X. & Wang, N. 2014, ApJ, 788, L16.
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23. Marshall F. E. , Guillemot L. , Harding A. K. , Martin P. , Smith D. A
Marshall F. E., Guillemot L., Harding A. K., Martin P., Smith D. A., 2015, arXiv:
Ruderman M. A., Sutherland P. G., 1975, ApJ, 196, 51
Shapiro S. L., Teukolsky S. A., 1983, Black holes, white dwarfs, and neutron stars, John Wiley & Sons, New York
Tong H., Xu R. X., Song L. M., et al., 2013, ApJ, 768, 144
Tong, H., Wang, W., 2014, arXiv:
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24. Thanks!!!