Neutrinos linked to an object outside our galaxy for the second time

NASA scientists have made an impressive discovery linking a rare particle called a high-energy neutrino to an object outside of our galaxy for only the second time ever. Scientists use both ground and space-based technologies, including the NASA Neil Gehrels Swift Observatory, to trace the neutrino directly to a black hole in the process of tearing a star apart.

The process of a black hole devouring a star, known as a tidal disruption event, is rare. NASA notes that astrophysicists have theorized that tidal disruptions could produce high-energy neutrinos, but this marks the first time the high-energy particle has been connected with observational evidence. The event in question is called AT2019dsg, and scientists note that the event didn't generate the neutrinos when or how scientists expected.

The unexpected observation helps the team to better understand how the phenomenon works. Neutrinos are called fundamental particles, and they are far more numerous than all the atoms in the universe but rarely interact with other matter. High-energy neutrinos are particularly interesting to astrophysicists because they have energies of up to 1000 times greater than those produced by the most powerful particle colliders on earth.

Scientists believe some of the most extreme events in the universe, such as violent galactic outbursts, can accelerate particles to nearly the speed of light. Those extremely fast particles collide with light or other particles in the universe generating high-energy neutrinos. The first high-energy neutrino source was discovered in 2018 and is a type of active galaxy called a blazar.

In this instance, a tidal disruption event is creating the neutrinos. Tidal disruptions happen when a star gets too close to a black hole, and gravitational forces create intense tides ripping the star apart and creating a stream of gas. The stream's trailing part escapes the system while the leading part swings back around to surround the black hole with a debris disc. In some instances, fast-moving particle jets are launched by the black hole. Researchers have theorized this type of event would create neutrinos early in the evolution during peak brightness.