When stars explode into supernovas, they produce shockwaves in the plasma surrounding them. Scientists say that the shockwaves are so powerful they can act as particle accelerators that blast streams of particles, called cosmic rays, into the universe at nearly the speed of light. One of the mysteries of science is how exactly the supernovas do that. Researchers have devised a new way to study the workings of this sort of astrophysical shockwave by creating a scaled-down version of the shock in the lab.
The scientists found that the astrophysical shocks develop turbulence at small scales that can’t be seen by observations. That turbulence helps kick electrons toward the shockwave before they are boosted to their final and extremely high speed. Researchers say that while the mechanics at play are fascinating, they’re so far away that it’s hard to study them.
They can learn more about the physics of astrophysical shocks in the lab and validate models. Researchers say that the astrophysical shockwaves around supernovas are not unlike the shockwaves and sonic booms that form in front of supersonic jets. One key difference is when a star explodes, it creates something physicists call a collisionless shock in the surrounding gas of ions and free electrons, or plasma. The individual electrons and ions are forced to move around by the intense electromagnetic fields within the plasma.
Researchers believe that supernova remnant shocks produce strong electromagnetic fields that bounce charged particles across the shock multiple times and accelerate them to extreme speeds. One key Mistry is that while scientists know the particles have to be moving very fast to be able to cross the shock in the first place, no one’s sure what gets the particles up to speed. To achieve their shockwaves in the lab, the team went to the National Ignition Facility, where they can use some of the most powerful lasers in the world and point them at a pair of carbon sheets to create a pair of plasma flows headed straight into each other.
When those flows met, optical and x-ray observations revealed all the features, the teams are looking for, meaning they had produced a shockwave in the lab in conditions similar to a supernova remnant shock. They found when the shock was formed, it was capable of accelerating electrons to nearly the speed of light. While the models could help reveal some fine points of the phenomena, the microscopic details of how the electrons reach the high-speed’s remains unclear.