CR3 stands out for its extremely low metallicity, a trait linked to first-generation stellar populations. The galaxy's light spectrum reveals strong hydrogen and helium emissions, but no measurable heavy elements. Its estimated age is 2 million years, total stellar mass is about 610 thousand solar masses, and dust is almost absent. These characteristics suggest CR3 matches theoretical predictions for a system formed from pristine, primordial gas. Direct evidence for ongoing Population III star formation at cosmic noon has not been observed previously.
Standard element-abundance calibrations show CR3 is the most metal-poor galaxy found from this epoch. The findings support the hypothesis that Population III star formation continued much longer than previously modeled.
Analysis of the galaxy's environment places CR3 in a region with slightly lower density than its surroundings. The researchers note that limited interaction and minimal galactic outflows have likely preserved CR3's near-original composition. The group suggests that pockets of unpolluted gas may remain and form stars even in relatively mature cosmic environments.
CR3 is the only galaxy with confirmed Population III characteristics found at cosmic noon. The team will continue spectroscopic observations to clarify CR3's formation history and seek similar objects for future research.
Research Report:A Metal-Free Galaxy at z = 3.19? Evidence of Late Population III Star Formation at Cosmic Noon
Related Links
Department of Astronomy, Tsinghua University
Understanding Time and Space
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