The Hubble Space Telescope has witnessed a collision between two jets of matter racing outward from a black hole at 98 percent of the speed of light. This is the first time ever that astronomers have witnessed such an event.
The black hole in the radio galaxy NGC 3862 is located roughly 260 million light years away from our own Milky Way.
Light saber-like jets emanating from galaxies can appear to be racing toward Earth significantly faster than the speed of light, a condition that is forbidden by the Special Theory of Relativity. This apparent violation of the laws of physics is due to an optical illusion, and astronomers hope this new finding helps them learn more about this strange effect.
Extra-galactic jets, which shoot material from the active nucleus of a galaxy in a thin beam, are not well understood. Analysis of the new data suggests that collisions within the beams accelerate material within their structure and increase the brightness of the gas.
Galaxy NGC 3862 was observed by Hubble several times over the course of 20 years. Astronomers used these images to create a video showing movement of the material away from the elliptical galaxy.
The jets emanating from NGC 3862 were first spotted in the constellation of Leo by astronomers using the Hubble telescope in 1992. They have a bumpy structure, much like a pearl necklace. The assembled video showed one of the knots, appearing to move at the superluminal speed of seven times the speed of light, catching up and colliding with a slower-moving clump of material. As the two collided, the event resulted in increased brightness from the scene of the accident. This behavior is expected to continue for several decades.
"Something like this has never been seen before in an extragalactic jet. This will allow us a very rare opportunity to see how the energy of the collision is dissipated into radiation," Eileen Meyer of the Space Telescope Science Institute (STScI) said.
Newly formed stars, as well as black holes, emit jets of gas in a fine beam, similar to a laser. Astronomers believe that the gas that comprises these features originally falls onto the star or near the black hole, where the material is super-heated. It is then ejected away from the body through acceleration delivered by the rotation of the central object. This stream of material is then focused into a beam by the force of magnetic fields around the star or black hole. At the beginning of this process, if the gas falling onto the star arrives in clumps, it can result in pulses of material at the end, producing the pearl necklace-like structure seen in NGC 3862.
A second video of a similar structure in a different galaxy is currently under development to determine if the same processes are occurring there as well.
Video of the jet and collision is available on Hank Campbell's YouTube channel.
Analysis of the gas jets produced by NGC 3862 was detailed in the journal Nature.