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

2010 Glitch in Vela Pulsar

Sarah BuchnerSKA Bursary conference

Dec 2010

Observing Vela with XDM 2

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

• surface of the earth moves by 15 m.


Vela Pulsar

• PSR 0833-45• Vela supernova remnant• About 10 000 years old• P = 0.089 s = 11.2 Hz


Vela Glitches

• Vela glitches

– Change in– Recovery contains exponential scales– 16 large glitches since 1969– Glitches every 1040 +- 326 days

69 1010

210


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

710


Vela Glitches From HartRAO


HartRAO bearing failure

• In October 2008 HartRAO 26m south polar bearing failed

• Started observing Vela with 15m XDM at HartRAO


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


• 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


XDM and HartRAO

• Use XDM to observe continuously (15 hour per day)

• Use HartRAO 26m to make transit observations


Waiting for Glitch


Observing Vela

• 22 July 2010 26m was repaired and begun normal observing once again

• Observed Vela approximately once hourly

-160.000

-159.500

-159.000

-158.500

-158.000

-157.500

-157.000

-156.500

-156.000

-155.500

-155.000

45000 46000 47000 48000 49000 50000 51000 52000 53000 54000 55000


10 days after 26m repaired…


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

91.1


Issued ATel


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


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


Post-glitch Observations


Determine nudot values


XDM data


Rotation Frequency

2010 Glitch

-5

0

5

10

15

20

25

55380 55400 55420 55440 55460 55480 55500 55520 55540

MJD

nu

* 1

E6 91.1


Nu dot from XDM


26 m data


Spin-down


The Standard Vela Glitch

3

1i

t

idgidet


Transients for Glitches

5 d50 d5d5d

0.5d0.5d

50d50d


Comparison with other Glitches


Comparison


Underlying Physics?


Neutron Star


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


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


Two-component model

intextcc NNI

)(I

N CSCint

)(I

NI CSCCC

)(I

I CSCSS


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

)(I

N CSCint


Non-linear coupling


Alpar Vortex Creep Model


But …

• Not all glitches are the same

• HartRAO archive data – 1994 double glitch


Overlaid Glitches with 1994


• 1994 glitch does not show transients• Regions do not decouple?

– Yet lag between superfluid and crust must change

• Different mechanism?• Is the model correct?


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


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


Conclusion

• Work continues on modelling post-glitch recovery• Can recovery be modelled by 3 distinct

exponentials?• What is the physical reason for this?


Thanks

KAT teamKAT teamHartRAO staffHartRAO staff


Questions / Thoughts?



Questions

• How fast does the crust spin-up?

• What is the recovery?– Interior of neutron star


Dedispersion and folding

DBE Dedisperse Fold Find TOA

BarycentreFind residuals

clock DM P

Std Profile

Pls position

Timestamp

Obs x,y,z


Arrival Times (TOA)

53075.871601404853076.606809902953076.631509316253076.635258953453076.639008589753076.745305551253076.772805320553076.814437082853076.8440091993


1st order - frequency

‘early’

‘late’

Observed - Predicted


2nd order


2nd order


Residuals

32.04 us


12 m @ Parkes

50.66 us

Hobbs et al, 20090907.4847


Residuals

32.04 us


XDM prototype at HartRAO

Kitty


KAT-7


KAT -> meerKAT


meerKAT



Neutron Stars and Pulsars


Observing Vela with XDM


Waiting for Vela to glitch


Storm clouds over HartRAO


XDM Observations

• Observing Vela with XDM• 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 – continous observing


Determine Glitch Epoch

Documents

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