Powerful lasers that mimic the effects of supernovas are now helping reveal how the magnetic fields of galaxies may have formed in the early universe, scientists reveal.
Nearly all galaxies, including our own Milky Way, have magnetic fields, ones that might affect how fast stars are born. However, where these fields come from has been a mystery.
The standard model for how these fields form is that tiny magnetic fields, which existed before galaxies evolved, served as cosmic "seeds" that were amplified over time by turbulence in the intergalactic medium. Still, it remains uncertain how these seed magnetic fields arose.
One notion is that they were generated by the so-called "Biermann battery effect," which is based on how the hydrogen making up most of the gas in the universe is made of negatively charged electrons and positively charged protons. Since electrons are much less massive than protons, they are much easier to push around, and outside pressures acting on both can drive electrons away from protons, creating an electric field. Eddies within the hydrogen can then set these electric charges spinning, generating magnetic fields. [The Strangest Things in Space]
"This mimics an explosion or a blast — say, like a supernova," said study lead author Gianluca Gregori, a physicist at the University of Oxford in England.
"We were able to reproduce, albeit in a scaled manner, plasma conditions found in the early universe directly in a laboratory setting," Gregori said.
In the future, the researchers would like to replicate their work with the largest laser available on Earth, the National Ignition Facility at Lawrence Livermore National Laboratory in California. "Ideally even more extreme conditions could be recreated," Gregori said.
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