Early Galaxy Cluster Reveals Unexpectedly Hot Gas

Astronomers have discovered a galaxy cluster in the early universe that contains gas far hotter than expected, challenging existing models of how these massive structures formed. The cluster, known as SPT234956, dates back to about 1.4 billion years after the Big Bang and features intracluster gas reaching temperatures of several tens of millions of degrees, roughly five to 10 times hotter than simulations predicted for that era.

The findings, based on observations with the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, were detailed in a study published Monday in the journal Nature. Researchers led by Dazhi Zhou, a doctoral candidate at the University of British Columbia, used the Sunyaev-Zeldovich effect—a method that measures the thermal energy of distant clusters by detecting how hot gas distorts cosmic microwave background radiation—to analyze the object. Initially, the team doubted the data because the signal appeared unusually strong. "We didn’t expect to see such a hot cluster atmosphere so early in cosmic history," Zhou said. "In fact, at first I was skeptical about the signal as it was too strong to be real. But after months of verification, we’ve...