For the first time an international team of astronomers has measured circular polarisation in the bright flash of light from a dying star collapsing to a black hole, giving insight into an event that happened almost 11 billion years ago.<\/p>\n
Dr Peter Curran from the Curtin University node of the International Centre for Radio Astronomy Research (ICRAR) was part of the team that observed Gamma-ray Burst 121024A \u2013 a bright flash of light emitted by a dying star collapsing to a black hole \u2013 and found a surprising detail in the light they collected.<\/p>\n
The research was published today in the prestigious journal Nature<\/i>.<\/p>\n
\u201cGamma-ray Bursts are so powerful that we can see them clearly at extraordinary distances,\u201d Dr Curran said.<\/p>\n
\u201cBut this one was an unusual case, its light had a strange feature \u2013 it was circularly polarised.\u201d<\/p>\n
If light is polarised it means the waves are moving in a uniform way as they travel \u2013 either bouncing up and down or left and right for linear polarisation, or in the case of circular polarisation, corkscrewing around in a spiral motion.<\/p>\n
Dr Curran said 3D movies made use of circular polarisation by feeding a different image to each eye through special glasses, giving the illusion of depth while watching a film.<\/p>\n
\u201cMost light in the natural world is unpolarised, the waves are bouncing around at random,\u201d he said.<\/p>\n
\u201cBut the light from this Gamma-ray Burst looked like it was part of a 3D movie \u2013 it was about 1000 times more polarised than we expected.<\/p>\n
\u201cThis means that the assumptions we\u2019ve been making about Gamma-ray Bursts need to be completely reconsidered \u2013 assumptions of how electrons are accelerated to the incredible speeds we observe.<\/p>\n
\u201cOur results show that Gamma-ray Bursts are far more complex than we thought.\u201d<\/p>\n
Gamma-ray Bursts are the brightest objects in the entire Universe, only lasting a fraction of a second, but sending out as much energy in that time as the Sun will in its entire life.<\/p>\n
These bursts are emitted by dying stars collapsing to black holes that form jets of material travelling at over 99.995 per cent of the speed of light.<\/p>\n
\u201cThese extreme objects are like super-powered versions of the world\u2019s largest and most powerful particle accelerator, the Large Hadron Collider, except very far away in space,\u201d Dr Curran said.<\/p>\n
\u201cWe can use them to study microscopic electrons and how they behave in extreme environments, at a great distance \u2013 in this case, 18,500 million light years away, at a time when the Universe was just a fraction of its current age.<\/p>\n
\u201cThis is the first time we\u2019ve found circular polarisation in the light from a Gamma-ray Burst, but we think we\u2019ll find it in more bursts in the future, so we can start to pin down what\u2019s actually happening when these bright flashes of energy are released.\u201d<\/p>\n
ICRAR is a joint venture between Curtin University and The University of Western Australia that receives funding from the State Government of Western Australia.<\/p>\n","protected":false},"excerpt":{"rendered":"
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