An international team of researchers used a powerful laser to reproduce the extreme conditions and energies that can be found during a gamma-ray burst. For the first time, they were able to confirm certain theoretical predictions scientists have made about these phenomena.
Gamma-ray bursts are very powerful and very brief emissions of high-energy light in the distant universe. Some of these events could be produced by neutron star collisions, but astronomers are still lacking a complete understanding of these phenomena. The answer, it seems, may come from the lab rather than the sky.
As reported in Physical Review Letters, the researchers employed the Gemini laser from the Rutherford Appleton Laboratory in the UK. The instrument is capable of delivering the power the Earth gets from the Sun in a region as thin as a hair.
To recreate (in scale) the extraordinary circumstances of a gamma-ray burst, the team used the laser to create a matter-antimatter beam, which was composed of electrons and their antimatter equivalent positrons. The team measured the intense magnetic field as the beam moved through a plasma and found that their observations were in line with general expectations from scientists.
“In our experiment, we were able to observe, for the first time, some of the key phenomena that play a major role in the generation of gamma-ray bursts, such as the self-generation of magnetic fields that lasted for a long time,” co-author Dr Gianluca Sarri, from Queen’s University Belfast, said in a piece published in The Conversation. “These were able to confirm some major theoretical predictions of the strength and distribution of these fields. In short, our experiment independently confirms that the models currently used to understand gamma-ray bursts are on the right track.”
The experiment is not just about astrophysics. A positron-electron beam is a weird state of matter and physicists are keen on getting a clearer picture of how different physical effects would be within such a state. Sarri notes that in a world made only of positrons and electrons, sound would not travel.
This research strengthens the current picture we have of gamma-ray bursts, but it also reminds us that to fully understand them we need to look at the universe. However, with gamma-ray bursts being such quick random events, their detection is laborious. If the neutron star collision hypothesis is confirmed in every or most cases, astronomers might be able to count on gravitational waves to spot more of these objects.