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2010 Glitch in Vela Pulsar

2010 Glitch in Vela Pulsar. Sarah Buchner SKA Bursary conference Dec 2010. Neutron Stars and Pulsars. Pulsar Glitches. Very good clock but … Sudden increase in frequency or “spin-up” Frequency increases by few parts per million In energy terms earthquake of 17 on Richter scale

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2010 Glitch in Vela Pulsar

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  1. 2010 Glitch in Vela Pulsar Sarah Buchner SKA Bursary conference Dec 2010

  2. Neutron Stars and Pulsars Observing Vela with XDM

  3. Pulsar Glitches • Very good clock but … • Sudden increase in frequency or “spin-up” • Frequency increases by few parts per million • In energy terms • earthquake of 17 on Richter scale • surface of the earth moves by 15 m. Observing Vela with XDM

  4. Vela Pulsar • PSR 0833-45 • Vela supernova remnant • About 10 000 years old • P = 0.089 s •  = 11.2 Hz Observing Vela with XDM

  5. Vela glitches Change in Recovery contains exponential scales 16 large glitches since 1969 Glitches every 1040 +- 326 days Vela Glitches Observing Vela with XDM

  6. Vela Glitches from HartRAO • The Vela Pulsar is observed three or more times daily on most days from 1985-2008 using the HartRAO 26m antenna. • Observations made at either S or L-band. • Online glitch detection – if a glitch is detected then continuous observing begins to catch exponential recoveries. • 10 large glitches observed Observing Vela with XDM

  7. Vela Glitches From HartRAO Observing Vela with XDM

  8. HartRAO bearing failure • In October 2008 HartRAO 26m south polar bearing failed • Started observing Vela with 15m XDM at HartRAO Observing Vela with XDM

  9. XDM observations • 26m pulsar timer was single channel pulsar timer. Produced a folded profile for each 55s observation • On XDM multi-channel iBob • Can access single pulse data Observing Vela with XDM

  10. Began observing Vela with XDM for 14.7 hours per day • First prize: Catch a glitch “in the act” • Second Prize: Parameterize the recovery • Free gift: • Pulsar timing provides exacting test of polarization and timing of XDM. • Soak test – continuous observing Observing Vela with XDM

  11. XDM and HartRAO • Use XDM to observe continuously (15 hour per day) • Use HartRAO 26m to make transit observations Observing Vela with XDM

  12. Waiting for Glitch Observing Vela with XDM

  13. Observing Vela • 22 July 2010 26m was repaired and begun normal observing once again • Observed Vela approximately once hourly Observing Vela with XDM

  14. 10 days after 26m repaired… Observing Vela with XDM

  15. Glitch Parameters • Glitch epoch • MJD 55408.802 • Vela was below horizon at the time • Last pre-glitch observation • 1.9 hour before glitch • First post-glitch observation • 7.4 hours after glitch • Glitch size Observing Vela with XDM

  16. Issued ATel Observing Vela with XDM

  17. FERMI follow-up • FERMI did not detect any increase of gamma-ray flux associated with the glitch • FERMI timing detected the timing glitch – epoch not well constrained Observing Vela with XDM

  18. Constraining Glitch Epoch • Regular observing allows glitch epoch to be constrained • 2006 Glitch observed with 26m • Glitch occurred during a LIGO science run • First direct search for grav waves assoc with glitch • No grav wave seen Observing Vela with XDM

  19. Post-glitch Observations Observing Vela with XDM

  20. Determine nudot values Observing Vela with XDM

  21. XDM data Observing Vela with XDM

  22. Rotation Frequency Observing Vela with XDM

  23. Nu dot from XDM Observing Vela with XDM

  24. 26 m data Observing Vela with XDM

  25. Spin-down Observing Vela with XDM

  26. The Standard Vela Glitch Observing Vela with XDM

  27. Transients for Glitches 0.5d 5d 50 d 50d 5 d Observing Vela with XDM

  28. Comparison with other Glitches Observing Vela with XDM

  29. Comparison Observing Vela with XDM

  30. Underlying Physics? Observing Vela with XDM

  31. Neutron Star Observing Vela with XDM

  32. Superfluid Rotation • Core of neutron star is superfluid • Rotates by means of array of quantised vortices • For superfluid to slow down vortex lines must move outward Observing Vela with XDM

  33. Vortices in inner crust • In inner crust vortices may pin to nuclei • This region of superfluid is then unable to spin-down at same rate as crust • Differential rotation develops • At glitch vortices unpin and angular momentum is transferred from crustal superfluid to crust causing the spin-up Observing Vela with XDM

  34. Two-component model Observing Vela with XDM

  35. Alpar Vortex Creep Model • Coupling between superfluid and the crust is a function of the lag between the velocities • At the time of the glitch • the crust spins up • The lag decreases • Hence the coupling decreases • Superfluid “decouples” • Torque acting on smaller I so spin-down increases • Recovery as region of superfluid recouples Observing Vela with XDM

  36. Non-linear coupling Observing Vela with XDM

  37. Alpar Vortex Creep Model Observing Vela with XDM

  38. But … • Not all glitches are the same • HartRAO archive data – 1994 double glitch Observing Vela with XDM

  39. Overlaid Glitches with 1994 Observing Vela with XDM

  40. 1994 glitch does not show transients • Regions do not decouple? • Yet lag between superfluid and crust must change • Different mechanism? • Is the model correct? Observing Vela with XDM

  41. Pulse Shape Changes • Recent paper by Weltevrede et al suggests glitch induced magnetospheric changes • Look for pulse shape changes • Look for increase of single pulses Observing Vela with XDM

  42. Conclusion • Observing Vela with XDM • First prize: Catch a glitch “in the act” • Vela was below horizon • Second Prize: Parameterize the recovery • 14.7 hours of observing enabled 0.5d time scale to be observed • Free gift: • Pulsar timing provides exacting test of polarization and timing of XDM. • Soak test – continuous observing Observing Vela with XDM

  43. Conclusion • Work continues on modelling post-glitch recovery • Can recovery be modelled by 3 distinct exponentials? • What is the physical reason for this? Observing Vela with XDM

  44. Thanks KAT team HartRAO staff Observing Vela with XDM

  45. Questions / Thoughts? Observing Vela with XDM

  46. Observing Vela with XDM

  47. Questions • How fast does the crust spin-up? • What is the recovery? • Interior of neutron star Observing Vela with XDM

  48. Dedispersion and folding Std Profile Dedisperse Fold Find TOA DBE DM P clock Timestamp Find residuals Barycentre Obs x,y,z Pls position Observing Vela with XDM

  49. Arrival Times (TOA) • 53075.8716014048 • 53076.6068099029 • 53076.6315093162 • 53076.6352589534 • 53076.6390085897 • 53076.7453055512 • 53076.7728053205 • 53076.8144370828 • 53076.8440091993 Observing Vela with XDM

  50. 1st order - frequency Observed - Predicted ‘early’ ‘late’ Observing Vela with XDM

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