Physics Behind Streaming Jets of High-Speed Matter in Space Explained on Earth
Streaming jets of high-speed matter create some of the most spectacular objects in space. These jets stream from young stars, X-ray binary stars and even from supermassive black holes at the centers of galaxies. Now, scientists may have answered what mechanism creates these jets, revealing a bit more about the physics of our universe.
Theoretical explanations for what causes these jets have been around for years. Yet astronomers have now used high-powered lasers to gain experimental verification of one proposed mechanism.
"This research is an example of how laboratory experiments can be used to test mechanisms that may produce what we observe in space," said Eric Blackman, one of the researchers, in a news release.
In this case, the researchers focused a very energetic laser beam on a tiny iron target. This allowed them to recreate a model of the beams in space and, more specifically, a supersonic plasma flow. With nothing to prevent the resulting iron plasma from spreading out, it flowed quasi-spherically from the target. The researchers then created another light, supersonic plasma from a plastic ring surrounding the central target in order to see the effects of a surrounding wind.
"The novelty of this experiment is in the way we spatially distribute the laser energy, with a central dot generating the iron flow and an outer ring incident on the plastic," said Alessandra Ravasio, one of the researchers, in a news release. "In this way we could create a nested geometry and study the interaction between the two flows."
The findings reveal that the interaction of the two plasmas sharply collimates the iron plasma flow. Instead of spreading out in all directions, the iron flow emanates primarily along a single direction. A shock wave is actually generated in this interaction, which helps the momentum and inertia of the plastic outer wind to collimate the inner iron flow into a jet.
The findings reveal how this particular phenomenon occurs-at least in the lab. It paves the way for future experiments, as well. For the time being, though, it looks as if the researchers have gathered some evidence for a mechanism for creating these space jets.
The findings are published in the journal Physical Review Letters.