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

66
2010 Glitch in Vela Pulsar Sarah Buchner SKA Bursary conference Dec 2010

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

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

2010 Glitch in Vela Pulsar

Sarah BuchnerSKA Bursary conference

Dec 2010

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Observing Vela with XDM 2

Neutron Stars and Pulsars

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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.

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Vela Pulsar

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

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Vela Glitches

• Vela glitches

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

69 1010

210

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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

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Vela Glitches From HartRAO

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HartRAO bearing failure

• In October 2008 HartRAO 26m south polar bearing failed

• Started observing Vela with 15m XDM at HartRAO

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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

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• 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

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XDM and HartRAO

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

• Use HartRAO 26m to make transit observations

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Waiting for Glitch

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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

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10 days after 26m repaired…

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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

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Issued ATel

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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

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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

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Post-glitch Observations

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Determine nudot values

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XDM data

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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

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Nu dot from XDM

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26 m data

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Spin-down

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The Standard Vela Glitch

3

1i

t

idgidet

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Transients for Glitches

5 d50 d5d5d

0.5d0.5d

50d50d

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Comparison with other Glitches

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Comparison

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Underlying Physics?

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Neutron Star

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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

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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

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Two-component model

intextcc NNI

)(I

N CSCint

)(I

NI CSCCC

)(I

I CSCSS

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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

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Non-linear coupling

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Alpar Vortex Creep Model

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But …

• Not all glitches are the same

• HartRAO archive data – 1994 double glitch

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Overlaid Glitches with 1994

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

– Yet lag between superfluid and crust must change

• Different mechanism?• Is the model correct?

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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

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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

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Conclusion

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

exponentials?• What is the physical reason for this?

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Thanks

KAT teamKAT teamHartRAO staffHartRAO staff

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Questions / Thoughts?

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Questions

• How fast does the crust spin-up?

• What is the recovery?– Interior of neutron star

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Dedispersion and folding

DBE Dedisperse Fold Find TOA

BarycentreFind residuals

clock DM P

Std Profile

Pls position

Timestamp

Obs x,y,z

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Arrival Times (TOA)

53075.871601404853076.606809902953076.631509316253076.635258953453076.639008589753076.745305551253076.772805320553076.814437082853076.8440091993

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1st order - frequency

‘early’

‘late’

Observed - Predicted

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2nd order

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2nd order

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Residuals

32.04 us

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12 m @ Parkes

50.66 us

Hobbs et al, 20090907.4847

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Residuals

32.04 us

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XDM prototype at HartRAO

Kitty

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KAT-7

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KAT -> meerKAT

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meerKAT

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Neutron Stars and Pulsars

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Observing Vela with XDM

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Waiting for Vela to glitch

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Storm clouds over HartRAO

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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

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Determine Glitch Epoch