Universe May be Less Crowded with Galaxies Than We Thought

First Posted: Jul 02, 2015 12:11 PM EDT

The universe may be far less crowded than we thought. Scientists have created a new theory that reduces the estimated number of the most distant galaxies in the universe by 10 to 100 times.

"Our work suggests that there are far fewer faint galaxies than we once previously thought," said Brian O'Shea, one of the researchers, in a news release. "Earlier estimates placed the number of faint galaxies in the early universe to be hundreds or thousands of times larger than the few bright galaxies that we can actually see with the Hubble Space Telescope. We now think that number could be closer to ten times larger."

In this latest study, the scientists used a supercomputer to run simulations to examine the formation of galaxies in the early universe. They simulated thousands of galaxies at a time, including the galaxies' interactions through gravity or radiation.

The simulated galaxies were actually consistent with observed distant galaxies at the bright end of the distribution. In other words, they were consistent with those that had been discovered and confirmed. The simulations didn't reveal an exponentially growing number of faint galaxies, though. Instead, the number of those at the lower range of the brightness distribution was flat rather than increasing sharply.

The Hubble Space Telescope can only see the tip of the iceberg as far as the most-distant galaxies go. And while the James Webb telescope will improve views of distant galaxies, the telescope has a relatively small field of view. As a result, the observations must take into account cosmic variance.

"A deeper understanding based on theory may be necessary to correctly interpret what's being seen, such as high redshift survey results," said O'Shea.

The findings are published in the Astrophysical Journal.

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