Live fast, die young: a massive 'dead red' galaxy seen for the first time

The discovery of massive galaxy that stopped making any new stars by the time the Universe was only 1.65 billion years old means we may have to rethink our theories on how galaxies formed. The galaxy, known as ZF-COSMOS-20115, formed all of its stars (more than three times as many as our Milky Way has today) through an extreme starburst event. But it stopped forming stars to become a “red and dead” galaxy not much more than a billion years after the Big Bang. Such galaxies are common in our Universe today but not expected to have existed at this ancient epoch. Galaxies turn red when they stop forming stars due to the resulting absence of hot, blue stars that have very short lifetimes. This discovery by our team sets a new record for the earliest massive red galaxy, with details published in Nature this month. It is an incredibly rare find that poses a new challenge to galaxy evolution models to accommodate the existence of such galaxies much earlier in the Universe.