New Study Reveals Colliding Galaxies Trigger Quasar Activity

For 60 years, quasars have been one of the most enigmatic objects in the universe. Their brightness is equivalent to a trillion stars compressed into a space the size of our solar system, yet scientists have been unable to explain what triggers such powerful activity.[0] However, a recent study led by scientists from the Universities of Sheffield and Hertfordshire has shed light on the phenomenon, revealing that quasar activity is a consequence of galaxies colliding.

The study, published in the Monthly Notices of the Royal Astronomical Society journal, is the first to image a sample of quasars of this magnitude with exceptional sensitivity.[1] By comparing observations of 48 quasars and their host galaxies with images of over 100 non-quasar galaxies, researchers have found that galaxies hosting quasars are approximately three times as likely to be interacting or colliding with other galaxies.

Quasars represent one of the most extreme occurrences in the universe, and their characteristics may foreshadow the future of our own Milky Way galaxy. Observations of quasars may offer insight into the future collision between the Milky Way and Andromeda galaxy, which is anticipated to happen in about five billion years.

At the center of most galaxies are supermassive black holes, many million times denser than the sun.[2] However, most of the time, the substantial amounts of gas within galaxies are orbiting at large distances from the galaxy centers, out of reach of the black holes.[0] Collisions between galaxies drive the gas towards the black hole at the galaxy center. Just before the gas is consumed by the black hole, it releases extraordinary amounts of energy in the form of radiation, resulting in the characteristic quasar brilliance.[1]

The activation of a quasar could have extensive implications for complete galaxies. A quasar eruption aftermath may lead to the ejection of the remaining gas from the galaxy.[0] For billions of years ahead, the formation of new stars within the galaxy can be stopped by the release of gas.[1] Quasars play a significant role in astrophysics as they possess remarkable luminosity, making them invaluable beacons for investigating the earliest stages of the universe.[1]

“It’s an area that scientists around the world are keen to learn more about – one of the main scientific motivations for NASA’s James Webb Space Telescope was to study 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,” comments Dr. Jonny Pierce, Post-Doctoral Research Fellow at the University of Hertfordshire.[2] “Quasars play a key role in our understanding of the history of the Universe, and possibly also the future of the Milky Way.”

The researchers detected structures in the outer regions of galaxies hosting quasars, indicating that these galaxies were colliding. The revelation illuminates the perplexing mystery regarding the genesis of quasar behavior. Professor Clive Tadhunter from the University of Sheffield says, “It’s exciting to observe these events and finally understand why they occur – but thankfully Earth won’t be anywhere near one of these apocalyptic episodes for quite some time.”

The findings have significant implications for our understanding of the universe and our own galaxy.[2] Quasars provide an insight into the earliest epochs in the history of the universe, and their behavior can foreshadow the future of the Milky Way. The study’s revelations have brought us one step closer to understanding the mystery of quasars and the forces that govern the universe.

0. “Astronomers solve the 60-year mystery of quasars, the most powerful objects in the universe”, 26 Apr. 2023,

1. “Quasars Shine Bright Like a Trillion Stars: Scientists Reveal Their Source of Energy” Revyuh, 25 Apr. 2023,

2. “Astronomers solve mystery about quasars – and the likely future of the Milky Way” Sky News, 26 Apr. 2023,

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