Astronomers have discovered something that challenges long-standing ideas about how the universe evolved: a galaxy cluster filled with extremely hot gas that formed far earlier than scientists thought possible.
The finding suggests that the universe was building massive structures faster — and more violently — than current theories predict.
The discovery, reported in Nature, comes from an international team of researchers led by scientists in Canada.
They found a galaxy cluster glowing with scorching gas just 1.4 billion years after the Big Bang.
Until now, astronomers believed gas in such young clusters should be much cooler, only heating up later as clusters mature over billions of years.
“We really didn’t expect to see something this hot so early in cosmic history,” said lead author Dazhi Zhou, a PhD researcher at the University of British Columbia. At first, the signal seemed almost too strong to be real.
After months of careful checks, however, the team confirmed that the gas is at least five times hotter than current models predict — and in some cases hotter than gas found in many galaxy clusters today.
The object at the centre of this surprise is a young, rapidly growing cluster known as SPT2349-56. Astronomers are seeing it as it appeared around 12 billion years ago, when the universe was still in its early stages.
Despite its youth, the cluster is already massive. Its central region spans about 500,000 light-years, similar in size to the halo surrounding the Milky Way.
Inside this compact space are more than 30 actively growing galaxies. Together, they are forming stars at a staggering rate — more than 5,000 times faster than our own galaxy. This intense activity makes SPT2349-56 one of the most extreme environments ever observed at such an early time.
To measure the heat of the gas between these galaxies, known as the intracluster medium, the researchers used a powerful observational technique called the Sunyaev–Zeldovich effect.
The observations were made using the Atacama Large Millimeter/submillimeter Array, a network of radio telescopes in Chile capable of studying the cold and distant universe with extraordinary precision.
What could be heating the gas so dramatically? The researchers suspect the answer lies in several newly discovered supermassive black holes within the cluster. As these black holes feed on surrounding matter, they release enormous amounts of energy, pumping heat into the surrounding gas and shaping the cluster far earlier than expected.
Until now, scientists believed galaxy clusters slowly heated up as gravity pulled them together over time. This discovery suggests the process may be much faster and more explosive. The team now hopes to understand how intense star formation, active black holes and super-heated gas all interact in such a young system.
By revealing a galaxy cluster that seems to have grown up far too fast, the finding forces astronomers to rethink how the largest structures in the universe were built — and how early cosmic chaos may have shaped the universe we see today.
