Stars form from cold molecular interstellar gas, which is relatively rare in the local Universe, such that galaxies like the Milky Way form only a few new stars per year. However, typical massive galaxies in the distant Universe formed stars much more rapidly, suggesting that young galaxies were more rich in molecular gas. The results of a survey of molecular gas in samples of typical massive star-forming galaxies when the Universe was 40% and 24% of its current age now reveal that distant star-forming galaxies were indeed gas rich.
- L. J. Tacconi
- R. Genzel
- B. Weiner