It's not just during your morning commute that you're at risk of being rear-ended. It turns out that cosmic balls of gas and dust also suffer from impatient, galactic tailgaters.
Eileen Meyer of the Space Telescope Science Institute (STScI) discovered the cosmic collision while compiling a video of a galaxy, named NGC 3862, that's part of the constellation Leo. The footage shows a "light saber-like" jet being spewed out of a black hole. But the jet isn't streamlined and smooth; instead it's clumpy and there are distinct, bright globs of matter. Since the researchers followed the jet for more than a decade, they were able to yield some interesting results about its evolution over time.
Breakdown of the movement of globules in NGC 3862 jet and when they merge via NASA
In 1994, there were three distinct pearls of bright material trundling out of the central galaxy. By 2002, the central bead of matter was catching up with the bead furthest from the galaxy, and in 2014, the two spheres of matter merged and became suddenly brighter. It seems that the front ball wasn't going fast enough for the impatient central ball, resulting in a cosmic collision.
The collision might not seem strange until you learn that these balls of matter blast through space at 98% the speed of light. It appears that the central puff of matter had to break the speed of light to catch up with the final one.
This data gives scientists a valuable opportunity to try and delve into the mystery of astrophysical jets. They are still not well understood, and scientists can only speculate how they form and what powers them.
Current theories say that a central black hole drags matter towards itself using its powerful gravitational attraction. The matter is heated up as it gets closer to and starts spinning around the central black hole. The powerful magnetic field around the black hole concentrates some of the matter at opposite ends of the black hole, and they occasionally get shot out into space. If the infalling matter is not continuous then the outgoing jets will be clumped together and thus not ejected continuously, just like the jet in the video shown below.
Compilation of four photos of the NGC 3862 jet showing two of the jet's globules merging into one bright globule via NASA
One proposed explanation for the collision is that the second knot of matter had less drag than the first in order to catch up. “Something like this has never been seen before in an extragalactic jet,” said Meyer. As the knots continue merging they will brighten further in the coming decades. “This will allow us a very rare opportunity to see how the energy of the collision is dissipated into radiation.”
Meyer's exploration of galactic jets won't stop here; she is already busy making more videos of jets in the nearby universe.
1