Astronomers solve the 60-year mystery of quasars, the most powerful objects in the universe

By learning that galaxies merging is what ignites quasars, the brightest, most potent objects in the universe, scientists have solved one of their greatest riddles.

Quasars, which were first identified 60 years ago, have the brightness of a trillion stars concentrated into an area the size of our solar system. Since they were originally noticed, it has been a mystery as to what may have caused such intense activity. It has just been discovered that it is a result of galaxies colliding together, according to new research undertaken by experts from the Universities of Sheffield and Hertfordshire.

Monthly Notices of the Royal Astronomical Society is where the work is published.

Researchers used deep imaging data from the Isaac Newton Telescope in La Palma to find the collisions after noticing deformed patterns in the quasar-hosting galaxies' outer regions.

Supermassive black holes are found in the cores of most galaxies. They also contain a significant quantity of gas, but for the most part, this gas is circling far from the galaxy centers and is therefore beyond of the black holes' range. The black hole at the heart of the galaxy is drawn into the gas by collisions between galaxies; just before the gas is sucked into the black hole, it releases enormous quantities of energy in the form of radiation, giving the quasar its distinctive brightness.

The emergence of a quasar can have drastic effects on whole galaxies; it can expel the galaxy's remaining gas, preventing it from producing new stars for billions of years.

This is the first time a sample of this size of quasars has been observed at this sensitivity level. Researchers came to the conclusion that galaxies harboring quasars are around three times as likely to be interacting or colliding with other galaxies by comparing views of 48 quasars and their host galaxies with pictures of over 100 non-quasar galaxies.

We now have a much better knowledge of how these strong things are started and fed thanks to the study.

"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 in about five billion years," said Professor Clive Tadhunter from the Department of Physics and Astronomy at the University of Sheffield.

Fortunately, Earth won't be in the path of one of these cataclysmic incidents for quite some time. "It's exciting to observe these events and finally understand why they occur."

Quasars are significant to astronomers because, because of their brilliance, they shine out at great distances and serve as beacons to the universe's early eras.

"It's an area that scientists around the world are keen to learn more about," says Dr. Jonny Pierce, Post-Doctoral Research Fellow at the University of Hertfordshire. "NASA's James Webb Space Telescope was designed with the primary goal of studying the earliest galaxies in the universe, and Webb is capable of detecting light from even the most distant quasars, emitted nearly 13 billion years ago. Our understanding of the universe's past and perhaps even the Milky Way's future depends heavily on quasars.