2023-04-26 02:52:51
First discovered 60 years ago, quasars can be as bright as a trillion stars packed into a volume the size of our Solar System.
Scientists from the Universities of Sheffield and Hertfordshire (United Kingdom) have unraveled one of the greatest mysteries of quasars, the brightest and most powerful objects in the Universe, by discovering that are lit by the collision of galaxies, as published in the magazine ‘Monthly Notices of the Royal Astronomical Society’.
When two galaxies collide, gravitational forces push enormous 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 in about 5 billion years.
First discovered 60 years ago, quasars They can shine as bright as a billion stars andpacked 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, carried out by observing 48 galaxies that host quasars and comparing them with 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 of the Isaac Newton telescope of La Palma, they observed the presence of distorted structures in the outer regions of galaxies that host quasars.
Most galaxies have supermassive black holes at their centers. They also contain substantial amounts of gas, but most of the time this gas orbits at great distances from the centers of galaxies, out of reach of black holes.
Collisions between galaxies push gas toward the black hole at the center of the galaxy; just before being consumed by the black hole, the gas releases extraordinary amounts of energy in the form of radiation, which gives rise to the characteristic brilliance of quasars.
The ignition of a quasar can have dramatic consequences for entire galaxies: it can expel the rest of the galaxy’s gas, preventing the galaxy from forming new stars billions of years into the future.
It is the first time that a sample of quasars of this size has been obtained with this level of sensitivity. By comparing observations of 48 quasars and their host galaxies with images of more than 100 non-cusar galaxies, the researchers concluded that the quasar-hosting galaxies are approximately three times more likely to be interacting or colliding with other galaxies.
The study has been a major step forward in our understanding of how these powerful objects are triggered and fueled. According to the teacher Clive Tadhunter, of the Department of Physics and Astronomy at the University of Sheffield, “cusars are one of the most extreme phenomena in the Universe, And it is likely that what we see represents the future of our own galaxy, the Milky Way, when it collides with the Andromeda galaxy some five billion years from now.”
“It’s exciting to watch these phenomena and finally understand why they happen, but luckily the Earth won’t be anywhere near one of these apocalyptic episodes for quite some time,” he adds.
Quasars are important to astrophysicists because, due to their brightness, stand out at great distances and therefore act as beacons of the earliest times in the history of the Universe.
The doctor Jonny Pierce, postdoctoral researcher at the University of Hertfordshire, explains that “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 able to detect light from the most distant quasars, emitted nearly 13 billion years ago. 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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