Supermassive black holes 'too big' for the early universe may not be so massive after all

In the four years that the James Webb Space Telescope (JWST) has been making observations of the early universe, it has been delivering one scientific milestone after another.

However, the $10 billion telescope has also left astronomers with a massive problem — literally.

The JWST has been routinely spotting supermassive black holes in the early universe that, at hundreds of millions of times the mass of the sun, are too big to have grown to such monstrous sizes before the universe was even 1 billion years old.

These cosmic titans are also too massive in comparison to the masses of their small host galaxies, challenging what astronomers know about the relationships between supermassive black holes and their galactic homes that are usually observed in the modern universe.

Now, new research suggests this isn't such a massive problem after all.

The team behind this research thinks that it is all a matter of perspective, and that these early supermassive black holes aren't as monstrous as scientists have estimated.

"We estimate masses of roughly one to ten million solar masses , compared with the tens or hundreds of millions previously inferred," team leader Alessandro Trinca of the Italian National Institute for Astrophysics (INAF) Astronomical Observatory of Rome told Space.com.

"These are still enormous objects, comparable to the four-million-solar-mass black hole at the center of the Milky Way, or a few times larger, but they lie at the lower end of the supermassive black hole population rather than among the most extreme examples.

"Importantly, these masses are much more consistent with the small galaxies that host them." The answer to this puzzle may lie in missing X-rays While considering the mystery of "overmassive" black holes in the early universe , Trinca and colleagues picked up on another puzzle associated with these objects.

To reach such sizes, these black holes must be voraciously feeding on surrounding gas and dust.

Such feeding black holes and the cosmic larders of gas and dust that surround them are usually extremely bright emitters of X-rays.

But this doesn't seem to be the case with the supermassive black holes in the early universe seen by the JWST.

The team looked at 14 X-ray-silent supermassive black holes, finding that there is another way of considering this lack of emission.

"Almost none of them are detected in X-rays, even in very deep observations with NASA's Chandra X-ray Observatory ," Trinca said.