PerspectiveAstronomy

Galaxy formation through cosmic recycling

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Science  02 Dec 2016:
Vol. 354, Issue 6316, pp. 1102-1103
DOI: 10.1126/science.aah6255

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Summary

Extremely massive galaxies are seen in the young universe, but their presence is puzzling because we do not yet understand how they became so massive so quickly. How do they get enough fuel to form stars so rapidly? The raw fuel for forming stars is cold molecular gas, and although this gas is common within young galaxies (1), we do not know how it is replenished once the first reservoirs are converted into stars. On page 1128 of this issue, Emonts et al. (2) report observations that may provide our first clue to this fueling problem. They have detected a giant reservoir of recycled molecular gas that is replenishing the fuel supply of one of the most massive galaxies in the young universe.