All galaxies have a supermassive black hole at their center. A new finding doesn’t contradict that observation, but it does suggest that we’ve been overestimating just how heavy some of these black holes actually are.
Astrophysicists using the Very Large Telescope (VLT) in Chile found evidence that the black hole of an infant galaxy was ten times smaller than what theoretical models predicted. If they can find similar behavior in other galaxies, it would mean that we’re even more blind to the dynamics of the early universe than we believed. The study, forthcoming in the journal Astronomy and Astrophysics, is currently available as a preprint on arXiv.
“We have been wondering for years how it’s possible we discovered all these fully grown supermassive black holes in very young galaxies shortly after the Big Bang,” said Seb Hoenig, study co-author and an astronomer at the University of Southampton, in a statement. “Our results suggest the methods to weigh these black holes used previously are just not working reliably in the early universe.”
A gassy veil
For the study, the researchers trained the VLT on an extremely luminous and distant quasar, which likely formed in the earlier days of the universe. Recent technological advances allowed the team to get a remarkably clear picture of how the black hole’s gravitational pull was shaping the matter nearby.
The researchers were surprised by the amount of thick, dusty gas swirling around the black hole, which was sucking up the gas at an astonishing rate. This simultaneously created an extreme outflow of gas from the black hole, they reported in the paper. In fact, around 80% of the gas around the black hole was flowing out, not in, according to study co-author Taro Shimizu, an astrophysicist at the Max Planck Institute for Extraterrestrial Physics in Germany, in a related release.
To an unknowing observer, this could make the black hole appear to be larger than it actually is, Hoenig said. “Think of it like a cosmic hairdryer set to maximum power: the intense radiation around it is blowing everything away that approaches it.”
As if to prove Hoenig’s point, closer scrutiny of the data revealed that the supermassive black hole was about 800 million times the mass of our Sun—still gigantic, but about 10 times smaller than theoretical predictions.
The elusive early universe
Astronomy has made great strides in understanding the dynamics of our universe, but there are still many unanswered questions. A good portion of these questions concern the state of our universe’s very early days.
The implications of the new finding are a new piece of the puzzle and a reminder of how much there is yet to be found.
“If our findings are typical, it means black hole masses in the early Universe may have been systematically overestimated,” Hoenig said. “It could lead to a re-evaluation of our models of cosmic evolution.”