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

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

• Vela glitches

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

69 1010

210

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

710

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

-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

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

91.1

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

2010 Glitch

-5

0

5

10

15

20

25

55380 55400 55420 55440 55460 55480 55500 55520 55540

MJD

nu

* 1

E6 91.1

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

3

1i

t

idgidet

Observing Vela with XDM 27

Transients for Glitches

5 d50 d5d5d

0.5d0.5d

50d50d

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

intextcc NNI

)(I

N CSCint

)(I

NI CSCCC

)(I

I CSCSS

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

)(I

N CSCint

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 teamKAT teamHartRAO staffHartRAO 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

DBE Dedisperse Fold Find TOA

BarycentreFind residuals

clock DM P

Std Profile

Pls position

Timestamp

Obs x,y,z

Observing Vela with XDM 49

Arrival Times (TOA)

53075.871601404853076.606809902953076.631509316253076.635258953453076.639008589753076.745305551253076.772805320553076.814437082853076.8440091993

Observing Vela with XDM 50

1st order - frequency

‘early’

‘late’

Observed - Predicted

Observing Vela with XDM 51

2nd order

Observing Vela with XDM 52

2nd order

Observing Vela with XDM 53

Residuals

32.04 us

Observing Vela with XDM 54

12 m @ Parkes

50.66 us

Hobbs et al, 20090907.4847

Observing Vela with XDM 55

Residuals

32.04 us

Observing Vela with XDM 56

XDM prototype at HartRAO

Kitty

Observing Vela with XDM 57

KAT-7

Observing Vela with XDM 58

KAT -> meerKAT

Observing Vela with XDM 59

meerKAT

Observing Vela with XDM 60

Observing Vela with XDM 61

Neutron Stars and Pulsars

Observing Vela with XDM 62

Observing Vela with XDM

Observing Vela with XDM 63

Waiting for Vela to glitch

Observing Vela with XDM 64

Storm clouds over HartRAO

Observing Vela with XDM 65

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

Observing Vela with XDM 66

Determine Glitch Epoch