Supervoid Discovered Near Mysterious Cold Spot
A cold cosmic mystery may have been solved. The Cold Spot, which is a larger-than-expected unusually cold area of the sky in the map of radiation leftover from the Big Bang, may finally have an explanation.
The Cold Spot originated from the Big Bang itself. It could actually be a rare sign of exotic physics that the standard cosmology does not explain. If it's caused by a foreground structure between us and the cosmic microwave background (CMB), though, it would be a sign that there is an extremely rare large-scale structure in the mass distribution of the universe.
In this latest study, the researchers used data from Hawaii's Pan-STARRS1 (PS1) telescope located on Haleakala, Maui, and NASA's Wide Field Survey Explorer (WISE) satellite. The researchers found a large supervoid, a vast region about 1.8 billion light-years across, in which the density of galaxies is much lower than usual in the known universe. The supervoid is actually only about 3 billion light-years away from us, which is a relatively short distance in the cosmic scheme of things.
Imagine there is a huge void with very little matter between you and the CMB. Now think of this void as a hill. As light enters the void, it must climb this hill. If the universe were not undergoing accelerating expansion, then the void would not evolve significantly, and the light would descend the hill and regain the energy it lost as it exited the void. However, the universe is accelerating in its expansion; this means that the hill is measurably stretched as the light is traveling over it and as the light descends the hill, the hill has become flatter and so the light cannot pick up all the energy it's lost.
While the existence of the supervoid doesn't fully explain the Cold Spot, it's very unlikely that the supervoid and the Cold Spot in the same location are a coincidence. The scientists plan to continue their studies to study the objects and find out a bit more about them.
The findings are published in the journal Monthly Notices of the Royal Astronomical Society.
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