When the universe first began to take shape, a few hundred million years after the Big Bang – 13.82 billion years ago – most astronomers think it was a chaotic place. The relatively short amount of time should have meant that galaxies formed in irregular clumps, rather than the defined shapes like spirals that we see today.
But a new study, published in The Astrophysical Journal Letters, has suggested that this is not necessarily the case, and large disk galaxies – similar to our own Milky Way – could have formed just 500 million years after the Big Bang. If true, it would suggest that the early universe was much more structured and ordered than we thought.
The research involved creating a detailed simulation of the cosmos, named BlueTides, covering an area 100 times greater in volume than anything before. The researchers from the University of California, Berkeley and the Carnegie Mellon University (CMU) in Pittsburgh, Pennsylvania used the National Science Foundation’s (NSF) supercomputer Blue Waters to create the simulation.
They used known constraints for the early universe, particularly the cold dark matter theory, which explains how our universe went from a homogenous state to one with clumps of matter – galaxies – that we see today. To their surprise, the researchers found that some disk galaxies were able to form just 500 million years after the Big Bang.
“It’s awe inspiring to think that galaxies much like our own existed when the universe was so young,” said Tiziana Di Matteo, professor of physics at CMU and a coauthor of the study, in a statement.
“The deepest Hubble Space Telescope observations have thus [far] only covered small volumes of space and have found very irregular, clumpy galaxies at these early epochs. It is not surprising that in these small volumes some of the small galaxies do not have regular morphologies like large disk galaxies. Similarly, numerical simulations have been limited in size so they have only made predictions for the smaller, clumpier galaxies at these early times.”
The team now hopes to use upcoming telescopes like the James Webb Space Telescope (JWST) and the Wide-Field Infrared Survey Telescope (WFIRST), scheduled for launch in 2018 and the mid-2020s respectively, to search for galaxies in the early universe that conform to this simulation.
“We argue that wide-field satellite telescopes (e.g. WFIRST) will in the near future discover these first massive disk galaxies,” the researchers note in their paper. “The simplicity of their structure and formation history should make possible new tests of cosmology.”