Young Galaxy Cluster Already Mature
“Isn’t that special.” The remark, in common parlance, is a generic way of avoiding a judgment call. When astronomers were confronted with the sight of a galaxy too mature for its age, Space.com reported the response: “And that makes it special, researchers said.”
The headline was, “Surprise! Ancient Galaxy Cluster Still Looks Young.” Actually, that is backwards. It should read, “Young Galaxy Cluster Looks Mature.” The import of the story is that a remote mature-looking cluster has been found, dating from a time, according to big-bang cosmology, when the universe was in the adolescence of its presumed 13.7-billion-year age. “The surprising thing is that when we look closely at this galaxy cluster, it doesn’t look young,” an astronomer said; “many of the galaxies have settled down and don’t resemble the usual star-forming galaxies seen in the early universe.”
The cluster, labeled CL J1449+0856, was observed by the European Southern Observatory’ Very Large Telescope (VLT), at the Paranal Observatory in Chile.” It had “all the hallmarks of being a very remote galaxy cluster,” but looks like “a mature object, similar in mass to the Virgo Cluster, the nearest rich galaxy cluster to the Milky Way, researchers said.” They based their age estimate on the cluster’s ability to trap hot gas near its center – gas that gives off characteristic X-rays.
How to explain the anomalous age? Space.com quoted Raphael Gobat from Paris:
“These new results support the idea that mature clusters existed when the universe was less than one quarter of its current age,” Gobat said. “Such clusters are expected to be very rare according to current theory, and we have been very lucky to spot one. But if further observations find many more, then this may mean that our understanding of the early universe needs to be revised.”
Gobat did not explain why any mature galaxies would exist at that young age, or how any theory predicted how rare they might be. One thing they agreed on, though, was that the cluster’s maturity “makes it special.”
This announcement is another in a long tradition of anomalous sightings of early maturity (01/08/2002, 09/21/2005, 04/02/2009). It’s like finding an old man in the maternity ward (10/14/2005). If this keeps up, the infants in the maternity ward are going to be the “special” ones. Yes indeed; if that happens, “this may mean that our understanding of the early universe needs to be revised,” Gobat said, going to bat for his colleagues. The dubious word there is understanding. Do revisions include overhauls or scientific revolutions? And to whom does his pronoun our refer? Maybe some mavericks already have more understanding not at risk of revision.