text: A giant supervoid 1.8 billion light-years across may be responsible for a mysterious ‘Cold Spot’ in the universe. The theory was proposed by astronomers seeking to understand what is causing this larger-than-expected cold area. If confirmed, the supervoid would be the largest single structure ever found by humanity. Hawaii scientists say a supervoid may account for an anomaly in the cosmic microwave background radiation (CMB) of the universe, shown bottom right. In 2004 astronomers first found the 'Cold Spot' - a region 20 per cent less dense than elsewhere - and may now have an explanation for its formation . The research, published in Monthly Notices of the Royal Astronomical Society, was carried out by the Institute for Astronomy at the University of Hawaii at Manoa. The Cold Spot was first discovered by astronomers in 2004 when they were examining a map of the radiation left over from the Big Bang - the cosmic microwave background (CMB) - made using Esa's Planck telescope. In the map, the universe is fairly evenly distributed, apart from in this one area. The huge unexpected region contains about 20 per cent less matter than other regions of the universe and about 10,000 less galaxies. While other sparse regions have been discovered, nothing on this scale has been found before. ‘Statistically, we are very confident that the supervoid is there,’ Dr András Kovács, who was involved in the study, told MailOnline. He said that the supervoid appears to be ‘roughly spherical’, and it may even contain a ‘significant substructure’ at its centre; a void within a void. A supervoid is not empty, but rather a region of space that has less matter than other parts of the universe. For this reason it can ‘sap’ the energy of light that is passing through it. To explain how that works, imagine the void to be a hill. As light enters the void and travels towards its middle, it can be said to be climbing the hill, using up energy. Once it passes the centre, it would begin ‘descending’ the hill and regain the energy it expended to get there. But as the universe is expanding, by the time the light gets to the centre, its route out has become ‘shallower’ - or less dense. This means it cannot regain as much energy as it lost initially and leaves the void with less energy, therefore a longer wavelength, which corresponds to a colder temperature. The different is marginal - typically about 70 nano-Kelvins - but it is enough to stand out when the entire cosmic microwave background radiation (CMB) of the universe is measured. The supervoid is thought to be causing a 'less-dense' region of the universe (illustration of empty space shown). At 1.8 billion light-years across it would be the biggest object ever found. But some 'exotic physics' is also needed to explain what's happening . The huge unexpected Cold Spot region, shown, contains about 20 per cent less matter than other regions of the universe, and about 10,000 less galaxies. While other sparse regions have been discovered, nothing on this scale has been found before . The original theory was that the Cold Spot originated from the Big Bang, and was a rare sign of 'exotic physics' that our current models of the universe could not explain. This new theory, however, suggests otherwise. Previous attempts to find a void at the distance of the Cold Spot were unsuccessful, but this latest study suggests it is actually a foreground object, three billion light-years from Earth. According to lead researcher Dr Istvan Szapudi, the object - if confirmed - would be ‘the largest individual structure ever identified by humanity.’ The team gathered data using Hawaii’s Pan-Starrs1 (PS1) telescope on Haleakala, Maui, and Nasa’s Wide Field Survey Explorer (Wise) satellite. The findings by the researchers were made using Nasa’s orbiting Wide-Field Infrared Survey Explorer (Wise) telescope (artist's illustration shown), which was launched on 14 December 2009, and Hawaii’s Pan-Starrs1 (PS1) telescope on Haleakala, Maui . However, the supervoid can only account for about half of the entire Cold Spot, suggesting there might still be some exotic physics at play. The researchers note, though, that it is ‘very unlikely’ that the supervoid and the Cold Spot being in the same location are a coincidence. They are continuing to study the void with improved data from PS1, and from the Dark Energy Survey being conducted with the Cerro Tololo Inter-American Observatory in Chile.
target: Hawaii scientists say a supervoid may account for a cosmic anomaly .
  The object is thought to be causing a 'less-dense' region of the universe .
  At 1.8 billion light-years across it would be the biggest object ever found .
  But some 'exotic physics' is also needed to explain what's happening .