We don’t know what the galaxy called RAD12-B is doing, but it must be something terrible. This is because the satellite galaxy is launching a jet of hot plasma directly at it, which (if we’re going to be anthropomorphic about it) looks like a targeted attack. Discovered in observations by a team led by astronomer Ananda Hota of the University of Mumbai in India, this is the sixth galaxy pair to have such explosive plasma activity. But the RAD12 system is unique for several reasons, and astronomers aren’t sure why.

First, it’s the first time we see a galaxy blasting a jet of plasma into a galaxy larger than itself. On the other hand, there is only one jet. We have seen many galaxies launching jets of plasma into space, and these jets often come in pairs. It’s a mystery why there is only one RAD12.

High-speed plasma jets emitting radio waves are quite common in the universe. These are known as radio galaxies and the jets are emitted by the galactic core. Scientists believe that the supermassive black hole at the center of the galaxy is responsible for this. Galactic supermassive black holes are often surrounded by an enormous amount of material swirling around the disk and falling onto the black hole from the inner edge of the disk. But this accumulation process is complex; all material on the inner edge of the disc does not go beyond the event horizon.

Some of it is deflected and accelerated along magnetic field lines outside the black hole. It is transported to the poles of a black hole, where it is launched into space at near the speed of light in vacuum, blasting long distances in the intergalactic medium, acting as a synchrotron to accelerate electrons, and then emitting radio waves. .

There’s still a lot we don’t understand about this process, but it often occurs in elliptical galaxies—the kind that are fuzzy, amorphous droplets, as opposed to the highly structured forms of spiral galaxies. Elliptical galaxies do not typically produce many stars; Most of their stars are old and don’t contain much star-forming material. Jets are thought to play a role in this by providing “feedback” that inhibits star formation.

The RAD12 system can help astronomers understand these processes because emissions place constraints on what certain classes of objects can and cannot do. Additionally, rare galaxy systems where the jet of one hits the other may exhibit positive feedback where the bomber galaxy shows signs of positive feedback or increased star formation activity.

Scientists have known since the 1990s that there is something unusual about RAD12, which is about a billion light-years away, but only because of a public science project to analyze data called RAD@home collected by the Giant Meter-Wave Radio Telescope (GMRT) in India. then they knew. All the weirdness was revealed.

The two galaxies in the system are in the process of merging, with their two cores located 414,000 light-years apart. Together, the entire structure is 440,000 light-years long and much longer than the jet’s parent galaxy (although it’s not uncommon for radio jets to exceed the diameter of the host galaxy). This means that the jet hit RAD12-B, but unlike five other galaxy systems of this type, RAD12-B shows no signs of positive feedback, that is, increased star formation activity.

And the host galaxy’s single jet stream is a real mystery. It is likely that something like “shells” of stars around the galaxy formed by a past merger that trapped the interstellar medium and gave rise to regions of higher density prevented it from escaping. We’ve also seen cases where radio jets are bent and deflected by strong magnetic fields in space. Understanding exactly what’s going on at RAD12 will require more work, including observations with multiple telescopes, but it promises to be truly fascinating.