An international team of astronomers has discovered the furthest cluster of galaxies yet, located 11.1 billion light-years from Earth. This is a momentous discovery, as it places the formation of this cluster just 700 million years after the Big Bang. In fact, we might be witnessing the birth of the cluster itself.
The galaxy cluster is called CL J1001+0220 (CL J1001 for short), and it was discovered by an international group of scientists led by Tao Wang of the French Alternative Energies and Atomic Energy Commission (CEA).
"This galaxy cluster isn't just remarkable for its distance, it's also going through an amazing growth spurt unlike any we've ever seen," said Wang in a statement
CL J1001 has 11 massive galaxies at its core, nine of which are going through a starburst phase where they are producing a huge amount of new stars. The core of the cluster has a star formation rate of 3,000 Sun-like stars per year, which is incredibly high even for a very young cluster like this one.
"It appears that we have captured this galaxy cluster at a critical stage just as it has shifted from a loose collection of galaxies into a young, but fully formed galaxy cluster," said co-author David Elbaz, also from the CEA.
Studying this cluster, astronomers were able to gain an insight into the differences between how galaxies evolve in and outside clusters in the early universe. Elliptical galaxies seem to be forming a lot more stars when they are inside clusters than when they are outside.
According to the paper, published in The Astrophysical Journal, the team also discovered that the galaxies seem to form more stars after they join the cluster rather than before, indicating that the interactions with other galaxies play a crucial role in creating stars.
CL J1001 also seems to have a lot more stars than the models and simulations were expecting, indicating that either galaxy clusters form more quickly than previously thought, or such clusters are very rare and they are not common in our computer simulations.
"We think we're going to learn a lot about the formation of clusters and the galaxies they contain by studying this object," said co-author Alexis Finoguenov of the University of Helsinki in Finland, "and we're going to be searching hard for other examples."