Velentina Boulter
Velentina Boulter is an intern at Cosmos as part of her Master of Journalism at the University of Melbourne.
Researchers have used a massive telescope to observe a pair of galaxies merging 12.8 billion years away, creating one of the brightest objects in the universe.
The research, published in the Astrophysical Journal, was led by Associate Professor Yoshiki Matsuoka from Ehime University and Professor John Silverman of from the Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU), both in Japan.
The object created is known as a high-luminosity quasar.
“I don’t know how to describe this system,” Matsuoka tells Cosmos. “This is a kind of a new category.”
“These quasars are really, really faint. But one surprise was that these are actually interacting, and we could get this super cool, brilliant image with robust evidence of galaxy interaction.”
Quasars can shine brighter than entire galaxies and are powered by supermassive black holes, which can be more than a billion times the mass of our Sun.
Scientists theorise quasars are created from the merging of gas-rich galaxies. While some of the gas is pulled towards the centre of the galaxy to fuel a black hole, some of the remaining gas gets compressed.
And it’s this gas compression that leads to an intense star formation period. During this time, the galaxies form a large number of stars, giving the quasar its radiant bright glow.
The luminosity of quasars can make them easy to spot, although scientists have often struggled to identify them in the pre-merger stage as they are too faint to detect.
While using the Hyper Suprime-Cam on the Subaru Telescope the team at Kavli IPMU was able to detect two very faint quasars next to each other.
Even though the pair was super faint, Matsuoka was taken back by how much gas they carried.
“We were able to compute the amount of gas of this system and found that the calculated total gas mass is ranked as one of the highest values found at that early universe so far, despite the fact that they are super faint.”
The data confirmed that these galaxies had around 100 billion times the mass of the Sun, which is even greater than most high-luminous quasars.
The quasars are approximately 12.8 billion light years away, which dates to the Cosmic Dawn era, when the universe was only 900 million years old.
“We can easily say that this system will merge in the near future, and after the merging event, we can expect a vigorous starburst activity,” Matsuoka says.
Identifying the pre-merger stage of high-luminous quasars can help our understanding of how they came to be and enrich our knowledge of what the early universe was like.
“Our prime motivation to do scientific research is to identify what is the evolutionary path to make massive black holes and what are the physical mechanisms to make that,” says Matsuoka.
The research team is seeking help from the James Webb Space Telescope to learn more about the physics of these objects.
“In principle, the number of fainter objects should be greater than the number of brighter objects,” says Matsuoka.
“So I expect that there are many, many of these kinds of merging systems, but we just didn’t realize those systems because they are faint. And so, I want to make an effort to identify and dig out these faint and closely paired systems.”
