Astronomers have for the first time witnessed a colossal merger of 14 galaxies that took place more than 12 billion years ago – providing a starting point into how galaxies evolve.
In a study published in the journal Nature, a team of international scientists used computer simulations of the galaxies to predict that, over time, this massive cluster will assemble to become the biggest structure in the modern universe.
Here’s all you need to know:
So why are we just seeing this megamerger now?
This densely-packed galactic smash-up, known as a protocluster, is located approximately 12.4 billion light years away.
This means its light started travelling when the universe was only 1.4 billion years old – about a 10th of its present age – and has just reached us.
Scott Chapman, an astrophysicist at Dalhousie University in Halifax, Canada – and one of the study authors, said: “Having caught a massive galaxy cluster in throes of formation is spectacular in and of itself.
“But, the fact that this is happening so early in the history of the universe poses a formidable challenge to our present-day understanding of the way structures form in the universe.”
How did the astronomers see this cosmic pile-up?
Using a powerful telescope called the Atacama Large Millimetre/submillimetre Array (Alma) in Chile, astronomers peered deep into space to witness the beginnings of the gargantuan merger.
The cosmic pile-up was observed “an astounding 90% of the way across the observable universe”, according to the team.
Alma allowed astronomers to identify 14 starburst galaxies undergoing an exceptionally high rate of star formation in a small region of space, confirming that this was a protocluster, called SPT2349-56, in very early stages of development.
Chapman said: “Alma gave us, for the first time, a clear starting point to predict the evolution of a galaxy cluster.”
So what does this all mean?
The scientists say a protocluster as massive SPT2349-56 should have taken much longer to evolve – because they are likely to contain vast amounts of dark matter and gargantuan black holes.
Tim Miller, a doctoral candidate at Yale University and co-author on the paper, said: “How this assembly of galaxies got so big so fast is a bit of a mystery, it wasn’t built up gradually over billions of years, as astronomers might expect.”
Computer simulations indicate that, over the next billion years or so, the 14 galaxies will merge into one giant elliptical galaxy surrounded stars and cosmic dust.
The researchers estimate this mega cluster will have a mass equivalent to 1,000 trillion suns, which would make it the largest known object in the universe.
