This galaxy cluster is nicknamed El Gordo, which means "The Fat One" in Spanish. Located seven billion light-years away, it's the biggest cluster ever found at that distance — and it's resounding proof that dark matter is everywhere in the cosmos.
The cluster is the result of two smaller clusters colliding into each other at several million miles per hour. It appears that this collision is actually pulling normal matter away from its dark counterpart, as the galaxy's hot gas has been slowed down by the collision while the dark matter keeps moving at the same speed.
Rutgers astronomer Felipe Menanteau, who led the study of this cluster, dramatically describes El Gordo as "the most massive, the hottest, and gives off the most X-rays of any cluster found so far at this distance or beyond." As the largest structures in the universe held together by gravity, galaxy clusters are an effective tool for studying the presence of dark matter and dark energy throughout the universe. Clusters will form in different ways depending on the amounts of these mysterious phenomena are present at that particular point in space and time.
It's extremely rare to find a cluster as massive as El Gordo this early in the universe's life — it comes from a time when the universe was about half its present age — but everything about it completely checks out with what astronomers would expect to find based on the current model, which holds that the universe began with the Big Bang and is largely made up of dark matter and dark energy.