An international team of astronomers made a puzzling discovery while observing some of the oldest regions in the known universe, dating back just 1.4 billion years after the Big Bang.
As detailed in a paper published in the journal naturethey discovered an extremely hot galaxy cluster that is hotter and older than current theory allows.
In other words, the discovered cluster is impossible according to our current best understanding of cosmology—which could upend our current understanding of how the early universe evolved.
“We did not expect to see such hot cluster atmospheres so early in the history of the universe,” lead author Dazhi Zhou, a doctoral student at the University of British Columbia, said in a statement about the discovery.
“In fact, I was skeptical about the signal at first because it was too strong and unreal,” he added. “But after months of verification, we confirmed that this gas was at least five times hotter than predicted and even hotter and more energetic than the gas we find in many star clusters today.”
Astronomers’ best theory is that, thanks to the black hole lurking at its core, the cluster has somehow gained a massive head start – one that was previously unimaginable even to top thinkers.
“This tells us that something in the early universe, possibly the three recently discovered supermassive black holes in the cluster, had pumped huge amounts of energy into their surroundings and shaped the young cluster,” added co-author Scott Chapman, a professor at Dalhousie University, “earlier and more intensely than we thought.”
Traditional theory holds that gas within galaxy clusters is pulled together and squeezed together due to increased gravity, thereby gaining energy. However, new research suggests there’s more to the evolution of these star clusters – perhaps even a separate source beyond these gravitational pulls.
The team discovered the strange readings while analyzing observations from the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile’s Atacama Desert, which examined an “infant” galaxy cluster called SPT2349-56.
The cluster dates back about 12 billion years and is massive: its core alone is about 500,000 light-years across. That’s about the size of the halo surrounding our Milky Way, a vast region of globular star clusters and older stars, but it produces stars more than 5,000 times faster.
Astronomers hope to find out what makes it so hot, a source of energy that defies our current models. Research shows that galaxy clusters evolve in more explosive ways than previously thought, aided by gravitational interactions between multiple supermassive black holes.
“We wanted to figure out how intense star formation, active black holes and superheated atmospheres interact, and what that tells us about how current galaxy clusters formed,” Zhou explained in the statement. “How is it possible for all of this to happen simultaneously in such a young, compact system?”
“Understanding galaxy clusters is key to understanding the largest galaxies in the universe,” Chapman said. “Most of these giant galaxies exist in star clusters, and their evolution is largely influenced by the very powerful environment when the cluster formed, including the medium within the cluster.”
More information about galaxy clusters: Scientists interested in dark matter bridges within giant galaxy clusters
