Ancient black holes grew faster than host galaxies, James Webb Space Telescope suggests

The MIT findings deepen the age-old question of what came first: the galaxy or black hole?

A James Webb Space Telescope image shows the quasar used in the MIT researchers' study into ancient supermassive black holes. Photo: MIT / Nasa
Powered by automated translation

New research using Nasa's powerful James Webb Space Telescope has shed light on how ancient black holes grew so massive and so rapidly that they surpassed the galaxies around them.

Led by a team of astronomers from the Massachusetts Institute of Technology (MIT) in the US, the study focused on the centres of galaxies known as quasars.

Quasars are extremely bright because they are powered by supermassive black holes, the largest type of a black hole that is more than 100,000 times the mass of the Sun.

A supermassive black hole's gravitational pull is so strong that it devours everything nearby, including light. The more it consumes, the brighter that quasar becomes.

But this intense light makes it difficult for scientists to see the stars in the surrounding galaxy.

But with the advanced imaging capabilities of the James Webb Space Telescope, MIT researchers were able to distinguish the faint light from stars around the black holes in some ancient quasars, dating back more than 13 billion years.

Using this data, the team found that these ancient supermassive black holes were much larger compared to the size of their surrounding galaxies than black holes today.

The study, published in the Astrophysical Journal, suggests that ancient black holes grew significantly faster than their host galaxies, with the black hole-to-galaxy mass ratio of around 1:10 compared to a modern-day ratio of 1:1,000.

“These black holes are billions of times more massive than the Sun, at a time when the universe is still in its infancy,” said Anna-Christina Eilers, co-author of the study.

“Our results imply that, in the early universe, supermassive black holes might have gained their mass before their host galaxies did and the initial black hole seeds could have been more massive than today.”

What came first: galaxy or black hole?

The researchers were able to gather this data using measurements of each quasar's light in different wavelengths.

They fed the numbers into a model that showed how much of that light was likely to come from the source itself or the galaxy's surroundings, such as scattered stars.

“This tells us something about what grows first: is it the black hole that grows first, and then the galaxy catches up? Or is the galaxy and its stars that first grow, and they dominate and regulate the black hole’s growth?” Ms Eilers said.

“We see that black holes in the early universe seem to be growing faster than their host galaxies. That is tentative evidence that the initial black hole seeds could have been more massive back then.”

Black holes may have boosted galaxy formation

A different study in February by the Johns Hopkins University focused on how black holes may have accelerated the birth of stars and supercharged galaxy formation.

The researchers, who also used the James Webb Space Telescope to make the observations, said distant galaxies appeared much brighter than they had predicted and revealed unusually high numbers of young stars and supermassive black holes.

It was always previously believed that black holes formed only after the collapse of enormous stars, with galaxies forming after the first stars lit up the early universe.

But the research suggests that black holes and galaxies may have coexisted and influenced each other during the first 100 million years.

“The big question is, what were our beginnings? The Sun is one star in 100 billion in the Milky Way galaxy, and there's a massive black hole sitting in the middle, too. What's the connection between the two?” said Joseph Silk, a professor in the department of physics and astronomy at Johns Hopkins University.

“Within a year we'll have so much better data, and a lot of our questions will begin to get answers.”

Updated: May 09, 2024, 3:00 AM