Scientists Discover Largest Structure in the Universe

Scientists have discovered what may be the largest structure in the entire Universe, according to a new study.

It is called a supervoid, a vast region 1.8 billion light-years across, in which the density of galaxies is much lower than usual in the known Universe. While this is incredible in itself, what researchers find particularly interesting is that this void is located in the same region as the Cold Spot, one of the most enigmatic mysteries of modern cosmology.

First found in 2004, the Cold Spot is described as a larger-than-expected unusually cold area of the sky, supposedly left over radiation from the Big Bang, or cosmic microwave background (CMB). The physics surrounding the Big Bang theory do predict warmer and cooler spots of various sizes in the infant Universe, but nothing on the scale of the Cold Spot.

However, the new giant expanse of emptiness may at least partially explain the existence of the Cold Spot, researchers suggest.

Due to what is known as the Integrated Sachs-Wolfe (ISW) effect, the supervoid may have sucked energy out of the CMB radiation that traveled across it. That is, as the Universe expanded during the Big Bang, the radiation traveling through the supervoid may have lost more energy than radiation traveling though "normal" space, creating an anomalously cool imprint, or Cold Spot.

Previous studies have shown that there is little evidence for a very distant structure in the direction of the Cold Spot. But, paradoxically, it is harder to identify large structures that are closer to us than further away. By constructing a 3-D map of galaxies, the researchers could confirm the presence of a massive supervoid, which adds weight to their theory.

This supervoid, located 3 billion light years from Earth - comparatively close in the cosmic scale of distances - was detected by analyzing data from the Pan-STARRS1 (PS1) telescope located on Maui in Hawaii and from NASA's Wide Field Survey Explorer (WISE) satellite.

While the existence of the supervoid and its expected effect on the CMB do not fully explain the Cold Spot, it is very unlikely that the supervoid and the Cold Spot at the same location are a coincidence. The team of scientists at University of Hawaii at Manoa plan to continue studying the Cold Spot and supervoid to get to the bottom of this mystery.

They reported their findings in the journal Monthly Notices of the Royal Astronomical Society.

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