First discovered 60 years ago, quasars can shine as brightly as a trillion stars compressed into a volume the size of our solar system. Ever since they were first observed, what could have caused such vigorous activity has remained a mystery. A new study by scientists from the Universities of Sheffield and Hertfordshire showed that it was the result of the disintegration of galaxies.

The collision was discovered when researchers, using deep observations of images from the Isaac Newton Telescope in La Palma, noticed the presence of distorted structures in the outer regions of galaxies that host quasars.

Most galaxies have supermassive black holes at their centers. They also contain significant amounts of gas, but often this gas circulates far from the centers of galaxies, out of reach of black holes. Collisions between galaxies send gas towards the black hole at the center of the galaxy; Just before the gas is consumed by the black hole, it releases an extraordinary amount of energy in the form of radiation, which causes the characteristic glow of a quasar.

A quasar ignition could have dramatic consequences for entire galaxies, removing residual gas from the galaxy and preventing new star formation for billions of years in the future.

This is the first time a quasar sample of this size has been imaged at this sensitivity level. By comparing observations of 48 quasars and their host galaxies with images of more than 100 non-quasars, the researchers concluded that galaxies hosting quasars are about three times more likely to interact or collide with other galaxies.

The research provided an important step forward in our understanding of how these powerful objects are initialized and operated.

Professor Clive Tadhunter, from the Department of Physics and Astronomy at the University of Sheffield, said: “Quasars are one of the most extreme phenomena in the universe, and what we are seeing probably represents the future of our Milky Way galaxy. The Andromeda galaxy is in about n billion years.

“It’s exciting to watch these events and finally understand why they happened, but thankfully Earth won’t be near one of these apocalyptic episodes for a while.”

Quasars are important to astrophysicists because they stand out from great distances thanks to their luminosity, and therefore serve as beacons for the earliest ages in the history of the universe. Dr Jonny Pearce, Research Fellow at the University of Hertfordshire explains:

“This is an area that scientists around the world are dying to learn more about – one of the main scientific motivations of NASA’s James Webb Space Telescope was to study the oldest galaxies in the universe, and Webb can detect light from even the oldest galaxies. “Distant quasars oscillated about 13 billion years ago. Quasars play a key role in our understanding of the history of the universe and perhaps the future of the Milky Way.”