The IRAM/GISMO 2 millimeter survey in the COSMOS field provides a unique view on star formation at the time when the Universe was only two billion years old. It reveals a significant population of extreme galaxies. Compared to the Milky-Way, they are about three times more massive, and form about 1000 times more stars per year. The sheer existence of these galaxies, soon after the Big-Bang, challenges current galaxy formation models.
https://iopscience.iop.org/article/10.3847/1538-4357/ab1912