Galactic pileup to become most massive structure in the cosmos
It’s a cosmic pileup in the far reaches of the universe, and nothing like it has ever been seen before.
Using the most powerful telescopes on Earth, astronomers have spotted 14 burning-hot galaxies hurtling towards each other on an inevitable galactic collision course at the edge of the observable universe.
Computer models show that when these galaxies do collide, they will form the core of a colossal galaxy cluster so large it will be the most massive structure known in the cosmos.
This chaotic, energy-filled region, described this week in Nature, is called a protocluster, and researchers say it is more active than any other section of the universe they have ever observed.
‘‘There are huge energetics involved, like 10,000 supernova going off at a time, quite literally,’’ said Scott Chapman, a physicist at Dalhousie University in Halifax, Canada, who worked on the study.
As if all that wasn’t crazy enough, the authors say the 14 galaxies are known as ‘‘starburst galaxies’’, which means they are forming stars at a furious rate.
The research team estimates that they could be making stars as much as 1000 times faster than the Milky Way.
And they are all crammed into a space just three times the size of our own galaxy.
In addition, the whole system is located 90 per cent of the way to the edge of the observable universe.
It is so far away that it takes light 12.4 billion years to travel across space from the protocluster to telescopes on Earth.
This means that this glowing
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star generator formed just 1.4 billion years after the universe itself came into being.
And it’s that fact in particular that has astrophysicists scratching their heads.
‘‘We don’t know how it is possible,’’ Chapman said. ‘‘We don’t know how you get those 14 galaxies right down the centre of the protocluster at such an early time.’’
Nothing that big and active should have been able to form so long ago, he said.
‘‘We see the structure of the universe building up slowly from little bits, and then merging together to make bigger bits. We don’t expect bigger galaxies to form until much later.’’
The earliest hint that something strange was going on in this part of the sky came in 2010, from data collected by South Pole Telescope Antarctica.
Although this instrument was designed to find relatively close galaxy clusters, astronomers realised it could also be used to spot extremely bright structures from a great distance away in both space and time.
The protocluster described in the new work showed up as a small the in but unusual smudge of light.
Still, astronomers found it compelling enough to request time on the ALMA telescope in the Chilean desert to take a closer look at its structure.
Observations made with ALMA revealed that the centre of the smudge was actually 14 distinct galaxies, and that the protocluster was a whopping 12.4 billion light years from Earth. – LA Times