The universe could be more crowded than we thought

An image captured as part of the Great Observatories Origins Deep Survey (GOODS)(Credit: NASA, ESA, the GOODS Team, and M. Giavalisco (University of Massachusetts, Amherst)

An international team of researchers has carried out an extremely precise survey of the observable universe, and estimated that there are around 10 times as many galaxies populating the cosmos than had previously been believed.

It is impossible to know the exact number of galaxies colonizing the universe. This is due in part to the technological limitations of present-day telescopes, but is also an inevitable result of the vastness of the cosmos, which is so expansive that the light from distant galaxies cannot be seen from Earth. Therefore, what we can see makes up the observable universe, but astronomers know that there is a great deal more we cannot see.

These barriers have not prevented astronomers from giving it their best shot, though. Based on an analysis of the Hubble Deep Field and Ultra Deep Field imaging campaigns, astronomers had estimated that there were some 200 billion galaxies waltzing their way across the unimaginable vastness of the cosmos.

However, while this may sound impressive, a fresh cosmic census is suggesting that astronomers had been dramatically underestimating just how cramped our universe really is.

The international team of researchers behind the new study used data from a number of observatories including Hubble, supplemented by advanced mathematical models capable of inferring the existence of galaxies that lie in the unobserved reaches of the universe.

With this data, the researchers created a 3D model, with which they estimated the number of galaxies that existed in each of the epochs that make up the history of our universe.

The team concluded that there could be a staggering two trillion galaxies populating the observable universe. The vast majority of these galaxies lie beyond the detection threshold of our current day telescopes, but when the introduction of the next generation of space- and ground-based observatories become operational, many of these illusive galaxies will slip into sight.

"It boggles the mind that over 90 percent of the galaxies in the universe have yet to be studied", comments Christopher Conselice, of the University of Nottingham, who led the research team. "Who knows what interesting properties we will find when we discover these galaxies with future generations of telescopes? In the near future, the James Webb Space Telescope will be able to study these ultra-faint galaxies."

Source: NASA

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