Cosmic dawn: The early universe 590 million years after the Big Bang. The green mesh shows a framework of dark matter, with the bright green denoting the most dense areas. The small dots denote young galaxies that are forming within the dark matter scaffold.
Credit: Orsi, A, Lacey CG, Baugh, CM, and Infante, L, Monthly Notices of the Royal Astronomical Society
LONDON: Scientists have used a computer to simulate what the universe would have looked like as galaxies began to form, 500 million years after the Big Bang.
The researchers 'rewound' the development of the universe through around 13 billion years to a period they call the 'cosmic dawn'. The model estimates how the earliest galaxies were distributed across the cosmos, highlighting ones that were churning out the most stars.
"This is the first time that we have had calculations for galaxy formation going back so far in the universe," said study author Carlton Baugh, a computational cosmologist from Durham University in England. What's more, the simulation is the first to attempt to explain how dark matter helped shape galaxies at this early time, he said.
Back in time
The study is published in the Monthly Notices of the Royal Astronomical Society.
Cosmologists already had some idea of how the universe evolved. In 2005, an international team of scientists created the Millennium Simulation, which showed how dark matter and cosmic background radiation evolved from the early universe.
The Durham team combined the data from that project with their model of galaxy formation – GALFORM – to create many possible simulations of how dark matter linked with infant galaxies during the cosmic dawn. Then, they fast-forwarded the models through time to the present day, until they found one that best matched what we see today.
"We have set the context for how structures grow in dark matter, [in the very early universe] and the role it plays in shaping galaxies," said Baugh. "Dark matter acts as a cosmic catalyst to kick-start galaxy formation [it]… was there before the cosmic dawn, giving some framework on which galaxies could form."
Dark matter is a mysterious form of matter that makes up over 80 per cent of the mass of the universe. It has never been directly detected, but physicists have inferred its presence due to the gravitational pull it exerts on light.
"This is the earliest epoch in which we've tested how dark matter fits in with visible matter," said Bob Nichol, a cosmologist from Portsmouth University, In England, who was not involved with the study. This study is just one of a suite of papers by Bough's team that simulates various phenomena in our universe, he said.
