2023-04-26 23:34:00
(CNN) — Astronomers discovered quasars 60 years ago, considered the brightest and most powerful objects in the universe, but did not know their origin. Now, scientists believe they have unveiled the mystery behind what lights these celestial objects.
Quasars have the same luminosity as a trillion stars contained in a space the size of our solar system, which is home to only one star, while the Milky Way is home to at least 100 billion stars.
The astronomers looked at 48 different galaxies containing quasars and compared them to more than 100 galaxies without them.
The researchers found that colliding galaxies is what likely spawns quasars, estimating that galaxies that host quasars are three times more likely to collide with other galaxies.
When two galaxies merge, huge amounts of gas are pushed into the supermassive black holes at their centers. Just before the gas is engulfed by the black holes, an enormous amount of energy is released in the form of jets of radiation, creating a quasar.
The astronomers used the Isaac Newton telescope, located on La Palma, which is part of the Canary Islands in Spain. Their in-depth observations revealed distorted structures in the outer regions of each galaxy that hosted a quasar.
Many large galaxies harbor supermassive black holes at their centers, as well as vast amounts of gas, but that gas is often out of reach for the hungry black hole at the galactic center. But when galaxies collide, all that gas is herded straight into the black hole, creating enough radiation to power a blindingly bright quasar.
The formation of a quasar can push the remaining gas out of a galaxy, depriving it of a key ingredient needed for star formation, sometimes for billions of years, according to a study published this Tuesday in the academic journal Monthly Notices of the Royal Astronomical Society.
“Quasars are one of the most extreme phenomena in the Universe, and what we see probably represents the future of our own galaxy, the Milky Way, when it collides with the Andromeda galaxy in about 5 billion years,” he says in a statement. Clive Tadhunter, study author and professor in the Department of Physics and Astronomy at the University of Sheffield.
“It’s exciting to watch these events and finally understand why they happen, but hopefully Earth won’t be anywhere near one of these apocalyptic events for quite some time.”
Studying bright quasars scattered across vast distances in the universe essentially allows scientists to look back in time. In 2021, scientists detected the most distant quasar to date, known as P172+18. The light from the quasar jets took 13 billion years to reach us, and the jets eject material at nearly the speed of sound.
“One of the main scientific motivations of NASA’s James Webb Space Telescope was to study the first galaxies in the Universe, and the Webb is capable of detecting light from the most distant quasars, emitted almost 13 billion years ago,” he explains in a Dr. Jonny Pierce, study co-author and postdoctoral researcher at the University of Hertfordshire, said in a statement. “Quasars play a key role in our understanding of the history of the Universe, and possibly the future of the Milky Way as well.”
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