Researchers managed to reveal one of the most intriguing mysteries in the cosmos: the origin of quasars.
Scientists from the Universities of Sheffield and Hertfordshire have unraveled one of the biggest mysteries of quasars by discovering that they are ignited by colliding galaxies.
When two galaxies collide, gravitational forces push huge amounts of gas toward supermassive black holes at the center of the colliding galaxy system.
Just before the gas is consumed by the black hole, it releases extraordinary amounts of energy in the form of radiation, giving rise to a quasar.
The Milky Way is likely to experience its own quasar when it collides with the Andromeda galaxy about 5 billion years from now.
the end of a mystery
First discovered 60 years ago, quasars can be as bright as a trillion stars packed into a volume the size of our Solar System.
Over the decades since they were first observed, what could trigger such powerful activity has remained a mystery.
The new work, done by looking at 48 quasar-hosting galaxies and comparing them to more than 100 galaxies without quasars, has now revealed that it is the result of colliding galaxies.
The collisions were discovered when the researchers, using deep imaging observations from the Isaac Newton telescope on La Palma, observed the presence of distorted structures in the outer regions of galaxies that host quasars.
The study, published in the Monthly Notices of the Royal Astronomical Society, has been a major step forward in our understanding of how these powerful objects are triggered and fueled.
According to Professor Clive Tadhunter, from the University of Sheffield’s Department of Physics and Astronomy, “Quasars are one of the most extreme phenomena in the Universe, and what we see is likely to represent the future of our own Milky Way galaxy, when it collides with the Andromeda galaxy about five billion years from now.”
“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,” he adds.
Quasars are important to astrophysicists because, due to their brightness, they stand out at great distances and thus act as beacons to the earliest epochs in the history of the Universe.