Webb Telescope uncovers hidden gas fueling star formation in Phoenix cluster
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New observations from NASA’s James Webb Space Telescope have solved a long-standing mystery surrounding the Phoenix galaxy cluster, revealing how hidden cooling gas enables rapid star formation.
This discovery challenges existing theories about galaxy cluster evolution and sheds light on a crucial process that had previously been missing from scientific models.
Located 5.8 billion light-years away, the Phoenix cluster hosts a supermassive black hole roughly 10 billion times the mass of the Sun. In most galaxy clusters, such black holes emit intense radiation, preventing surrounding gas from cooling and forming new stars. However, in the Phoenix cluster, astronomers have observed an unusually high rate of star formation, raising questions about the mechanisms at play.
By analysing data from Webb, along with observations from Hubble, Chandra X-ray Observatory, and ground-based telescopes, researchers have now identified the missing link in the cooling process - intermediate-temperature gas that bridges the gap between the hottest and coldest phases of star formation.
The findings, published in Nature, reveal that this intermediate-temperature gas, measuring around 540,000 degrees Fahrenheit, is distributed in cavities within the cluster.
Prior studies had indicated inconsistent cooling rates, making it seem as if gas was not reaching the necessary conditions for star formation. Michael McDonald, an astrophysicist at the Massachusetts Institute of Technology and principal investigator of the study, compared this inconsistency to a ski slope where more people reach the top than the bottom - suggesting that a crucial step was missing.
Webb’s Mid-Infrared Instrument (MIRI) played a key role in detecting the gas, particularly through its ability to observe faint neon VI emissions in the mid-infrared spectrum. Michael Reefe, the study’s lead author from MIT, emphasised that these observations provide a vital tool for studying star formation in other galaxy clusters.
Scientists now plan to apply these findings to other galaxy clusters to determine whether similar cooling processes occur elsewhere. While the Phoenix cluster exhibits extreme characteristics, the new methodology established using Webb’s observations could offer broader insights into how galaxies evolve.