- Largest ‘glitch’ ever measured in a gamma ray pulsar
- Mysterious burnt out stars usually emit regular pulses
- Find could help astronomers understand these mysterious objects
By Rob Waugh
PUBLISHED: 03:32 EST, 27 July 2012 | UPDATED: 03:32 EST, 27 July 2012
The pulsar J1838-0537 suddenly speeded up the rays it was blasting into space – and ‘glitched’, in a cosmic hiccup that scientists still don’t understand.
Even finding pulsars is extremely difficult – and the new discovery could throw light on these mysterious cosmic objects.
WHAT ARE PULSARS? THE MYSTERIOUS ‘BEACONS’ OF SPACE
Pulsars form when a star becomes unstable and goes supernova – first of all compressing into a tiny space before exploding. The explosion sheds almost all the material of the star off into the vacuum of space at almost ten per cent the speed of light.
All that is left is a tiny, spinning core – the pulsar – which rotates at astonishing speed, perhaps just seconds.
As it spins, it sends off highly concentrated beams of radio-waves, which to a distant stationary observer (for instance on Earth) appear to flash on and off in a regular pattern – the pulse of the pulsar star.
The odd new star was found as astronomers sifted astronomical data with supercomputers.
‘By employing new optimal algorithms on our ATLAS computer cluster, we were able to identify many previously-missed signals,’ says Bruce Allen, Director of the AEI.
Back in November 2011, Allen’s team announced the discovery of nine new Fermi gamma-ray pulsars, which had escaped all previous searches. Now the scientists have made a new extraordinary find with the same methods.
The name of the newly discovered pulsar – J1838-0537 – comes from its celestial coordinates.
‘The pulsar is, at 5,000 years of age, very young. It rotates about its own axis roughly seven times per second and its position in the sky is towards the Scutum constellation,’ says Holger Pletsch, a scientist in Allen’s group and lead author of the study which has now been published.
‘After the discovery we were very surprised that the pulsar was initially only visible until September 2009. Then it seemed to suddenly disappear.’
Only a complex follow-up analysis enabled an international team led by Pletsch to solve the mystery of pulsar J1838-0537: it did not disappear, but experienced a sudden glitch after which it rotated 38 millionths of a Hertz faster than before.
‘This difference may appear negligibly small, but it’s the largest glitch ever measured for a pure gamma-ray pulsar.’
The precise cause of the glitches observed in many young pulsars is unknown.
Astronomers consider “star quakes” of the neutron star crust or interactions between the superfluid stellar interior and the crust to be possible explanations.
‘Detecting a large number of strong pulsar glitches makes it possible to learn more about the inner structure of these compact celestial bodies,’ says Lucas Guillemot from the Max Planck Institute for Radio Astronomy in Bonn, the second author of the study.’