1. Hunting for Glitches Sarah Buchner

2. …are the leftover cores from supernova explosions. Almost black holes Neutron stars are very dense (10 17 kg/m 3 ) –1.5 M  with a diameter of 10 to 20 km –Mass 10 27 tons They rotate very rapidly: Period = 1.3 ms to 8 sec magnetic fields are 10 13 times stronger than Earth’s. Neutron Stars Chandra X-ray image of the neutron star left behind by a supernova observed in A.D. 386. The remnant is known as G11.2  0.3.

3. Pulsars and Neutron Stars

4. The Pulsar

5. Vela Pulsar PSR 0833-45 Vela supernova remnant About 10 000 years old P = 0.089 s = 11.2 Hz HartRAO observed most days since 1984

6. Pulsars – stable clock Massive stable flywheels  superb cosmic clocks e.g. Vela: Unambiguously number each pulse There were exactly 47 414 570 pulses between 11 Mar 2004 20:55:37 and 29 Apr 2004 21:41:37 OH masers Source below horizon VLBI

7. Phase residuals

9. Glitch Detection When phase offset > limit Continual observing begins Alarm at HartRAO sms observers Astronomical telegram / IAU circular

10. Spin-up

11. Recovery Recovery time scales 0.4 and 4.1 days

12. Cause of glitch - starquake  / =10 –6 = 10 ε = 10 -4  / =10 –6 = 10 ε = 10 -4

14. Vortex pinning and unpinning

15. Vortex pinning Vortex current depends on lag

16. Glitch

17. Spin-up

18. Linear coupling “resistive” Crust Pinned superfluid N ext N int

19. Simple model

20. Spin-down

21. Non-linear coupling “capacitive”

22. Post-glitch recovery

23. Recoveries have same form?

24. Predicting glitches

25. But …..

26. Do glitches occur randomly?

27. Size of angular momentum reservoir Slope sets a lower limit to

28. Crab vs Vela

29. How fast does the crust spin up? Can we catch a glitch in the act?

30. XDM Observations

31. Timing Vela with XDM

34. Thanks HartRAO workshop staff and astronomers Adriaan Hough Richard Lord Simon Ratcliffe