Galaxy mergers in the early universe could limit star formation Map of the cold molecular gas from the galaxy ID2299. Credit: A Puglisi et al. Astronomers have looked nine billion years into the past to find evidence that galaxy mergers in the early universe could shut down star formation and affect galaxy growth. New research led by Durham University, UK, the French Alternative Energies and Atomic Energy Commission (CEA)-Saclay and the University of Paris-Saclay, shows that a huge amount of star-forming gas was ejected into the intergalactic medium by the coming together of two galaxies. The researchers say that this event, together with a large amount of star formation in the nuclear regions of the galaxy, would eventually deprive the merged galaxy – called ID2299 – of fuel for new stars.