High molecular gas fractions in normal massive star forming galaxies in the young Universe

Understand

Stars form from cold molecular interstellar gas.

• Since this is relatively rare in the local Universe, galaxies like the Milky Way form only a few new stars per year.
• Typical massive galaxies in the distant Universe formed stars an order of magnitude more rapidly.
• Unless star formation was significantly more efficient, this difference suggests that young galaxies were much more gas rich.