Newfound massive galaxies may force theorists to revisit formation model
Peering into the center of five of the youngest clusters of galaxies known in the universe, astronomers recently found several full-grown, cigar-chomping adults among the myriad of toddlers. The remote galaxies hail from a time when the 13.7-billion-year-old cosmos was less than 5 billion years old. Yet measurements reveal that the bodies are just as massive as galaxies like the modern-day Milky Way, which took at least 10 billions years to mature.
The findings appear to call into question the leading theory of galaxy formation, known as the dark matter model — at least as it applies to the dense regions where galaxies congregate into clusters, says Chris Collins, an astronomer at the Liverpool John Moores University in England. He and his colleagues used the infrared Subaru telescope atop Hawaii’s Mauna Kea to observe the galaxies, and the team describes the findings in the April 2 Nature.