Ancient ‘lonely’ quasars discovery leaves scientists confused

The team of scientists led by MIT studied images taken by the James Webb Space Telescope taken between August 2022 and June 2023.

A new MIT-led study into five ancient quasars brought more questions than answers on how scientists previously believed these objects came to be.

A quasar is the blazing centre of a galaxy, hosting a supermassive black hole in its core. They are some of the oldest objects in the universe, having been observed as early as a few hundred million years after the Big Bang, which scientists estimate happened more than 13bn years ago.

Scientists have theorised that the earliest quasars emerged from overly dense regions of ‘primordial matter’ – the earliest matter in the universe, all packed together with no space between – which would also mean that many smaller galaxies would be within the quasars’ environments.

However, using NASA’s James Webb Space Telescope, a team of scientists from MIT, Leidin University, the University of California and ETH Zurich among others, has found that some quasars appeared to be drifting in voids, with only a few galaxies in its vicinity.

The team studied five known ancient quasars, formed between 600m and 700m years after the Big Bang, by looking back more than 13bn years using the telescope.

From the images taken by the James Webb between August 2022 and June 2023, the scientists found that quasars showed a “surprising variety” in their neighbourhoods, with some predictably residing in crowded fields, while others appeared to drift in voids that don’t contain much matter.

“Contrary to previous belief, we find on average, these quasars are not necessarily in those highest-density regions of the early universe. Some of them seem to be sitting in the middle of nowhere,” said Anna-Christina Eilers, an assistant professor of physics at MIT.

“It’s difficult to explain how these quasars could have grown so big if they appear to have nothing to feed from.

“Our results show that there’s still a significant piece of the puzzle missing of how these supermassive black holes grow,” Eilers says. “If there’s not enough material around for some quasars to be able to grow continuously, that means there must be some other way that they can grow, that we have yet to figure out.”

With very little matter in these barren regions, there is a possibility that the “lonely” quasars could be surrounded by galaxies that are heavily shrouded in dust, hiding them from the telescope’s view.

Because quasars are extremely bright, their light is able to travel over the age of the universe, far enough to reach the James Webb billions of years later.

“It’s just phenomenal that we now have a telescope that can capture light from 13bn years ago in so much detail,” Eilers says. “For the first time, [James Webb] enabled us to look at the environment of these quasars, where they grew up and what their neighbourhood was like.”

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