Virtual Universe Machine Shows How Galaxies Develop

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Researchers want to learn more about galaxy evolution using a newly-developed virtual universe machine, which is a model that shows how galaxies evolved over time. The research published in the journal Monthly Notices Of The Royal Astronomy Society may shed light on entities such as supermassive black holes at the hearts of those galaxies and their evolution.

Researchers at the University of Arizona developed a new computer simulation that looks at 12 million galaxies, stretching from time from about 400 million years following the Big Bang event to today. The model requires trillions of complex calculations and algorithms to make sense, and was modeled using a supercomputer which could generate 8 million variations of the universe’s model.

“On the computer, we can create many different universes and compare them to the actual one, and that lets us infer which rules lead to the one we see,” Peter Behroozi, the study’s lead author, said in a statement. “We took the past 20 years of astronomical observations and compared them to the millions of mock universes we generated. We pieced together thousands of pieces of information to see which ones matched. Did the universe we created look right? If not, we’d go back and make modifications, and check again.”

The model also revealed that dark matter and energy which are invisible to the radio telescopes play an important role in galaxy formation. The virtual universe machine showed galaxies based on the current expectations of dark matter. For example, when a dense amount of dark matter is present, galaxies are prevented from forming new stars during the early stages of their lives. Thanks to the new model, the galaxies appeared with more red hues than they are usually shown to have. The newly-developed model also matches what astronomers see in the universe. The galaxies needed to be adjusted to that perception before they could produce new stars and systems.

“As we go back earlier and earlier in the universe, we would expect the dark matter to be denser, and therefore the gas to be getting hotter and hotter. This is bad for star formation, so we had thought that many galaxies in the early universe should have stopped forming stars a long time ago,” Behroozi explained. “But we found the opposite: Galaxies of a given size were more likely to form stars at a higher rate, contrary to the expectation.”

Scientists have two ideas to why galaxies appear redder than usual. The first reason is because the galaxies that are older and formed during the early history of the universe are moving away faster, which causes the light to move toward the red spectrum. The other reason may be that the galaxy stopped forming new stars, and contains fewer blue stars which are known to die sooner.

“But we don’t see that,” Behroozi said. “If galaxies behaved as we thought and stopped forming stars earlier, our actual universe would be colored all wrong. In other words, we are forced to conclude that galaxies formed stars more efficiently in the early times than we thought. And what this tells us is that the energy created by supermassive black holes and exploding stars is less efficient at stifling star formation than our theories predicted.”

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