Hunting for Glitches Sarah Buchner

…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 tons They rotate very rapidly: Period = 1.3 ms to 8 sec magnetic fields are times stronger than Earth’s. Neutron Stars Chandra X-ray image of the neutron star left behind by a supernova observed in A.D The remnant is known as G11.2  0.3.

Pulsars and Neutron Stars

The Pulsar

Vela Pulsar PSR Vela supernova remnant About years old P = s = 11.2 Hz HartRAO observed most days since 1984

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

Phase residuals

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

Spin-up

Recovery Recovery time scales 0.4 and 4.1 days

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

Vortex pinning and unpinning

Vortex pinning Vortex current depends on lag

Glitch

Spin-up

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

Simple model

Spin-down

Non-linear coupling “capacitive”

Post-glitch recovery

Recoveries have same form?

Predicting glitches

But …..

Do glitches occur randomly?

Size of angular momentum reservoir Slope sets a lower limit to

Crab vs Vela

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

XDM Observations

Timing Vela with XDM

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