A Young Giant Galaxy Cluster

In the early universe, there was a huge amount of swirling matter and light that didn’t really have much structure.  Compared to today’s much more regular dotting of galaxy clusters and superclusters, the early universe was all over the place.  But as will all things, there had to be a first.  a first star, a first galaxy, and even a first galaxy cluster.

Astronomers have detected a massive, sprawling, churning galaxy cluster that formed only 3.8 billion years after the Big Bang. The cluster, shown here, is the most massive cluster of galaxies yet discovered in the first 4 billion years after the Big Bang. Credit: NASA, European Space Agency, University of Florida, University of Missouri, and University of California

The massive cluster of galaxies known as IDCS J1426.5+3508 is the most distant massive galaxy cluster ever discovered, and it has some interesting properties that point to how it formed and evolved so quickly.  One such property is that it has a bright knot of X-ray emission that is slightly off from the center of the cluster, suggesting it has undergone some recent upheaval.  This means the cluster’s core of hot gas has shifted from it’s spatial center, suggesting a violent collision with another young cluster and causing the gas to slosh around like water in a glass.

“In the grand scheme of things, galaxies probably didn’t start forming until the universe was relatively cool, and yet this thing has popped up very shortly after that,” says Michael McDonald, assistant professor of physics and a member of MIT’s Kavli Center for Astrophysics and Space Research. “Our guess is that another similarly massive cluster came in and sort of wrecked the place up a bit. That would explain why this is so massive and growing so quickly. It’s the first one to the gate, basically.”

Finding galaxy clusters in the early universe is difficult, but when you are able to identify one it often looks different from modern day clusters that have had time to evolve.  “They are sort of like cities in space, where all these galaxies live very closely together,” McDonald says. “In the nearby universe, if you look at one galaxy cluster, you’ve basically seen them all — they all look pretty uniform. The further back you look, the more different they start to appear.”

Study of such massive early structures gives astronomers insights into the state of the early universe and allows them to put constraints on a timeline of formation for the major structures of the galaxy.  Keep an eye on this one, I’m sure we are barely just scratching the surface of how unique and interesting it is.

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