Scientists have used laser beams 60,000 billion times more powerful than a laser pointer to recreate scaled supernova explosions in the laboratory to investigate one of the most energetic events in the universe.
Supernova explosions, triggered when the fuel within a star reignites or its core collapses, launch shock waves that sweep through a few light years of space.
“It may sound surprising that a table-top laboratory experiment that fits inside an average room can be used to study astrophysical objects that are light years across,” said Professor Gianluca Gregori of Oxford’s Department of Physics.
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“In reality, the laws of physics are the same everywhere, and physical processes can be scaled from one to the other in the same way that waves in a bucket are comparable to waves in the ocean. So our experiments can complement observations of events such as the Cassiopeia A supernova explosion,” said Gregori, who led the study.
The Cassiopeia A supernova explosion was first spotted about 300 years ago in the Cassiopeia constellation 11,000 light years away, its light having taken that long to reach us.
The optical images of the explosion show irregular ‘knotty’ features and associated with these are intense radio and X-ray emissions.
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Whilst no one is sure what creates these phenomena one possibility is that the blast passes through a region of space that is filled with dense clumps or clouds of gas.
“Our team began by focusing three laser beams onto a carbon rod target, not much thicker than a strand of hair, in a low density gas-filled chamber,” said Jena Meinecke, an Oxford graduate student who headed the experiment.
The heat generated was more than a few million degrees Celsius and caused the rod to explode. The dense gas clumps that surround an exploding star were simulated by introducing a plastic grid to disturb the shock front.
“The experiment demonstrated that as the blast of the explosion passes through the grid it becomes irregular and turbulent just like the images from Cassiopeia,” said Gregori.
The research was published in the journal Nature Physics .