Thursday, 27 April 2017 10:43

Mystery of the universe's Cold Spot deepens – it's not a supervoid

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A huge cold region of the universe spanning billions of light years is not a blank patch mostly empty of galaxies, astrophysicists have discovered.

The Cold Spot is an area where cosmic microwave background radiation – leftover radiation from the Big Bang – is weak. This makes it significantly colder than the average temperature for the universe. Across most areas of the sky, the temperature due to this radiation is about 2.73C above than absolute zero (-270C). But the Cold Spot is 0.00015C colder than this.

Previous theories suggested that the difference in temperature was because the Cold Spot was a ''supervoid'' with very few galaxies in it.

But analysis of galaxy redshift using new high-resolution data has shown that the Cold Spot has a similar structure to the rest of the universe in terms of its galaxies.

Researchers at Durham University looked at the redshifts of 7,000 galaxies using data from the Anglo-Australian Telescope. They found that the Cold Spot has the ordinary ''soap bubble'' structure of clusters of galaxies surrounding smaller voids. The results are published in a paper in the Monthly Notices of the Royal Astronomical Society.

With that explanation out of the window, the origin of the Cold Spot remains a scientific puzzle. Did the Cold Spot arise by chance, or was it caused by another as yet unknown astronomical event?

The chances of the Cold Spot arising by chance are about 1 in 50, according to standard cosmological theories.

The phenomenon can't be ruled out as an unlikely fluctuation explained by the standard model, but there are more exotic explanations, said study author Tom Shanks of Durham University.a.jpg

Cold Spot View photo
The Cold Spot could have been caused by a collision between our universe and another bubble universe, he said. This would leave a particular signature in the cosmic microwave background radiation. If this signature is found, it could be the taken as the first evidence for the multiverse.

Exactly how probable the remaining explanations for the Cold Spot are is hard to weigh up, Shanks told IBTimes UK.

"I have to balance the 1-in-50 chance that standard cosmology could produce this feature with the huge implications for physics if the bubble collision interpretation is correct - with implications for the multiverse, string theory, comsological constant and so on. Basically we need further evidence from present and future cosmic microwave background experiments to distinguish these two possibilities," Shanks said.

"What can be said with certainty is that our result means that there is now no possibility of explaining the Cold Spot by a foreground void in the galaxy distribution."

Source :International Business Times by Staff Reporter

 

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