Quasars are the most strongly radiating objects in the universe.
At their extremes, they shine as brightly as a trillion stars packed into the area of our solar system.
The first quasar was discovered more than 60 years ago, but until now their enormous power has remained a mystery.
In Monthly Notices of the Royal Astronomical Society published research reveals that quasars are the result of colliding galaxies.
Already in previous studies, it has been suggested that such a huge cosmic crash would explain the power of quasars, but no evidence was found for the theory.
Fresh in their study, the British researchers looked at the measurement data collected by the Isaac Newton telescope on the home galaxies of quasars and compared it with galaxies where these ultra-bright objects had not been observed.
They found that 65 percent of quasars’ home galaxies had collided with another galaxy. The collision probability was three times as high as in the other galaxies studied.
The researchers identified the collisions from the distorted structures visible at the outer edges of the star systems.
Most of them a supermassive black hole is collapsing at the center of galaxies.
In addition, there is a large amount of gas floating around in them, which usually circulates far from the center, out of reach of the black hole.
If two galaxies collide, however, the gas drifts towards the edge of the supermassive gap.
Before sinking into the black hole’s core, the gas heats up and an immense amount of radiation energy is released from it. It is this eruption that is called a quasar.
An eruption can have devastating effects on its environment. A powerful burst of radiation can push the remaining gas out of the galaxy, so that stars cannot be born there for billions of years.
Quasars are important research objects for astronomers, because due to their brightness it is possible to observe them from very far away.
For example, the James Webb space telescope studying the first moments of the universe has seen the light of quasars almost 13 billion years ago.
In addition to the past, quasars help to see the future, says Professor at the University of Sheffield Clive Tadhunter in the bulletin.
“What we see now may foreshadow the future of our Milky Way when it collides with the Andromeda galaxy in about five billion years.”
Published in Tiede magazine 7/2023
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