1. Predicting the BRAING INDEX OF INTERMITTENT AND NULLING PULSARS
Speaker
Abdujappar rusul
From CCNU

2. Content: Introduction to a pulsar and its braking index
Intermittent PSR B
A study of the braking index of intermittent pulsars and nulling pulsar
conclusions

3. Observations revealed that its spin axe and magnetic axe is not aligned in usual。
Observations confirmed that pulsar is a remnant of supernova explosion (Crab pulsar)
Pulsar magnetosphere is believed to be surrounded with charged plasma, which is created by the pair cascade near the star surface
The observed pulsar radio emission features showed that pulsar is broadband coherent radio emitting source

4. Emission prosperities
Vela pulsar
4min J J J
4 minute time series

5. Standard model of pulsar magnetosphere
According to the observed features, researchers proposed that pulsar emission is magnetic dipole radiation to see whether it is truly magnetic dipole radiation field or not, we always measure a parameter know as braking index

6. Measuring the braking index
In observation, the unresolved glitch in the data and unknown timing noise would not allow a precise measurement of spin frequency second derivatives; this results in unreliable braking index (Hobbs 2010)
Because the above reason, observers only measured 7-8 pulsars’ braking index among 2328 (From a talk of Lorimer) pulsars population

7. Measured Braking Indices

8. BRAKING INDEXTELLS………
Observed braking indices are all smaller than３
But the magnetic dipole field expected it as 3
This indicates that, in addition to magnetic dipole radiation, another physical process must contribute to the torque acting on pulsars (Livingstone et al. 2007).
Scientist believe that there must be additional energy loss by the out flowing charged plasma

9. Intermittent pulsar

10. “on”》“off” Intermittent pulsar
the difference between the “on” and “off” state rotational slow-down energy loss
Where T is torque generated by out flowing plasma current and magnetic field

11. Theorists have their luck!

12. The out flowing plasma current – pulsar wind
Intermittent pulsar
The observations of intermittent pulsar B confirmed the existence of out flowing current and provide us the relationship between the pulsar wind torque and magnetic dipole field torque
Later observations of intermittent PSR J , PSR J and nulling PSR B manifest the same feature as PSR B

13. significance because we need to know
We need further study about “on”
and “off” state magnetosphere configuration
Intermittent pulsar
Like many other pulsars, for the intermittent pulsar, the importance of the measurement of braking index has its
significance because we need to know
1. Dose “on” state braking index smaller than 3
2. Dose “off” state braking index equals 3 or not
Yet, observers could not measure the braking index of PSR B even after 13 yr of observation because of the lack of data about its transition into (or out of) a radio-on phase (Young et al. 2013).

14. The braking index of intermittent pulsars
It looks like, at least, we need a model to study about the braking index

15. The braking index of intermittent pulsars
We need to take time derivative to this equation
When we assume and are constant

16. The braking index of intermittent pulsars
We have the variables polar cap radius and charge density
With this 2 variables, we discussed 3 different cases
1. Charged density is constant
2. Polar cap radius is constant
3. both of them are variables

17. The braking index of intermittent pulsars

18. The braking index of intermittent pulsars
For the first case
Here, for simplicity, we only discuss the case 1

19. Observations show different “on”//”off” ratios in different observing epochs

20. The braking index of intermittent pulsars
Observations revealed that the braking index is constant in relatively short observing period, for example 0.5% in 21, ~2% in 40 years for Crab
So, we assume that the braking indices in “on” and “off” of neighboring observations are constant,

21. Results The braking index of intermittent pulsars
The calculated braking indices（ ）are all almost within the observed domain（ ）.

22. Results
Brake index changes with the spin-down ratio

23. conclusions
1. Under our model, we can predict the braking index of intermittent pulsar with their spin-down ratios
2. Results show that pulsar’s magnetosphere, may never become entirely depleted of plasma during the
“off” state and/or we probably missed another energy losing factor in our approach to study the intermittent pulsars.

24. Thanks
谢谢大家