The Milky Way has something of a torrid and violent history, given that our galaxy has fueled its own growth by cannibalistically devouring smaller galaxies. Now, astronomers have discovered evidence of our galaxy's earliest bout of cannibalism in the form of "scarring" at the heart of the Milky Way left behind by a galactic morsel it devoured around 12 billion years ago.
Working as part of the ARMA (Cluster Ages to Reconstruct the Milky Way Assembly) project, the team behind this discovery used dense conglomerations of ancient stars called globular clusters to find traces of a merger that occurred around 1.8 billion years earlier than the previously earliest known event of this type.
Prior to this, the history of the Milky Way colliding and merging with both smaller and larger galaxies had only been reconstructed up to around 10 billion years ago, around 3.8 billion years after the Big Bang. The earliest bout of cosmic cannibalism involved the collision with and consumption of the dwarf galaxy...
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