Birth of Distant Galaxy Cluster Challenges Early Universe Theories

Astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) have detected a large reservoir of hot gas in the still-forming galaxy cluster around the Spiderweb galaxy, the most distant detection of such hot gas yet. The discovery indicates that the system is on its way to becoming a proper, long-lasting galaxy cluster rather than dispersing. The team detected the intracluster medium (ICM) of the Spiderweb protocluster through the thermal Sunyaev-Zeldovich (SZ) effect, which happens when light from the cosmic microwave background passes through the ICM. The Spiderweb protocluster contains a vast reservoir of hot gas at a temperature of a few tens of millions of degrees Celsius, outweighing the cold gas previously detected by thousands of times.