This could be the most 'naked' giant black hole ever found

Right now astronomers are dealing with their own chicken-and-egg conundrum: Which came first, the galaxy or the big black hole inside it? 

Astronomers often estimate the weight of a black hole by using the brightness and width of certain light signals in space coming from hot gas. 

Some researchers have argued those methods severely exaggerate the masses of strange "little red dots" in the early universe. Since their discovery by NASA's James Webb Space Telescope, what they actually are has divided the community: Some think they contain growing black holes; others argue the black holes might be much smaller than they seem — or, might not exist at all. 

For the first time, a team took a direct measurement of a little red dot, Abell2744-QSO1, and found that not only were the earlier estimates pretty spot on, but also, the object almost certainly contains an enormous black hole, roughly 50 million times heavier than the sun. 

Then the study got weird. 

Normally, galaxies and their central black holes grow together: Big galaxy equals big black hole. But QSO1 barely seems to have a galaxy at all. The black hole may outweigh all the stars around it combined.  

"To our knowledge, this … makes QSO1 the most 'naked' massive [black hole] ever found," the authors wrote in their Nature paper. "This demonstrates the possibility of [black hole] primacy, that is, [black holes] forming and growing earlier than their host galaxy." 

To directly measure the object's mass, the researchers mapped the motion of glowing gas around QSO1's center. Credit: NASA / ESA / CSA / L. Furtak et al / A. Pagan

How astronomers directly measured it

Astronomers see QSO1 as it existed only about 700 million years after the Big Bang because of its extreme distance. 

To directly measure the object's mass, the researchers mapped the motion of glowing gas around QSO1's center. Gas near a massive object moves faster because gravity pulls harder on it. The team found that QSO1's gas rotated in a way that matched what physicists expect around a compact, extremely massive object.  

The researchers proceeded to test other explanations — like whether a tightly packed bundle of stars sat in the center instead of a black hole — but the numbers just didn't work. To explain the observations without a black hole, the stars would need to squeeze into an impossibly small area — much denser than known star clusters.  

A black hole is an area in space where gravity is so strong that not even light can escape it. A supermassive black hole is the same but on a vastly larger scale, containing millions or billions of times the sun's mass. The black hole at the center of the Milky Way, called Sagittarius A*, weighs roughly 4 million suns. Messier 87, the galaxy famous for providing the first direct image of a black hole, is as massive as 6.5 billion suns.

The James Webb Space Telescope has helped astronomers discover loads of "little red dots" in the early universe. Credit: NASA / ESA / CSA / STScI / D. Kocevski

Why they call it "naked"

The team describes QSO1 as a "naked" black hole because it appears to be sitting in a vacant, primitive environment — perhaps before a normal galaxy fully formed around it. 

Scientists still don't know how the first supermassive black holes formed so quickly after the Big Bang. The usual models for how galaxies grow struggle to explain these extreme cases. 

One idea is that a massive gas cloud collapsed directly into a black hole extremely early in cosmic history. Another concept scientists consider is that some kind of original black hole formed almost at the beginning of time, possibly within the first second. 

What's becoming clear is that some black holes were enormous from the get-go, somehow able to form without a gigantic host galaxy to feed them or a phase of many massive stars collapsing and merging, said Roberto Maiolino, a coauthor from the University of Cambridge in the United Kingdom, in a statement.

"It’s a paradigm shift," Maiolino said, "a total revisiting of the classical scenarios of how black holes form and grow."