ASTRONOMERS HAVE gone 12.7 billion years back in time to see the birth of one of the universe’s most impressive and massive features – a galaxy cluster.
The find is particularly important because it is the “youngest” yet found and will tell scientists a great deal about how galaxy clusters form and evolve.
A galaxy is a huge thing but a cluster is an amount of matter beyond comprehension. They can contain the equivalent of 400 billion suns of matter and often sport the largest black holes and giant quasars.
Now astronomers have found a virtual baby, a cluster that began to form just a billion years after the Big Bang that formed the universe. The only examples astronomers know today are much older and already formed but the newcomer, designated Cosmos-Aztec3, is still taking shape.
Details of the discovery were presented yesterday by Peter Capak, an astronomer from the California Institute of Technology, at the annual meeting of the American Astronomical Society in Seattle. The find is also published in the journal Nature.
Mr Capak describes the “protocluster” as a “metropolis in the making”, because such clusters are believed to grow like cities, absorbing outlying villages.
Galaxy clusters grow over billions of years, drawing together many galaxies and huge amounts of gas to form the largest structures in our universe.
This “urban sprawl” occurs because of the rapid star formation taking place in the cluster which occupies a space about 40 million light years across. For all this size, it is a remarkably dense part of the universe. It is producing about 4,000 new stars a year as material within the protocluster begins to coalesce and clump together.
“We are seeing the seeds of a galaxy metropolis, a city of galaxies that will eventually grow into a large city like London,” Dr Capak said, “but we’re seeing it when it was very small.”
The discovery was made under the Cosmos survey, a concentrated effort making use of many of the world’s major telescopes, trained on a large chunk of the night sky.
Until now we could only study the result of cluster formation but now the building of a galaxy cluster can be picked apart and compared with the related objects we see today.