Scientists have discovered the location of the universe's missing matter - the half of ordinary matter that could not be previously observed, but which scientists knew to exist.
When it comes to the search for missing matter, dark matter - the mysterious, invisible material accounting for roughly 80 precent of the mass of the universe - hogs the headlines.
Instead, under the action of gravity, matter is concentrated into so-called filamentary structures, forming a network of knots and links called the "cosmic web".
Two separate teams found the missing matter - made of particles called baryons rather than dark matter - linking galaxies together through filaments of hot, diffuse gas. Now, two independent teams of researchers have made claims for finding this missing matter and they have found it hidden in the cosmic web.
While the baryon filament theory has been suggested by scientists before, it has never been confirmed because the gas is exceptionally fine and is not hot enough for X-ray telescopes to observe. But researchers were able to confirm their existence using a phenomenon known as the Sunyaev-Zel'dovich effect, which describes the behavior of light left over from the Big Bang as it travels through hot gas.
In 2015, the Planck satellite created a map of this effect throughout the observable universe. The ionized gas causes a distortion in the cosmic microwave background. As this light moves through hot gas, some of it scatters, leaving a patch in the CMB. Researcher Hideki Tanimura from the University of British Columbia said that the final results of both the teams varied because they were looking at filaments at different distances. Still, these simulations too predict that entire galaxies and planets in the universe are connected by long filaments of usual matter.
Tanimura's team stacked data on 260,000 pairs of galaxies, and de Graaff's group used over a million pairs.
The Scottish team found the strands to be six times denser - confirmation they are dense enough to form filaments between galaxies.
'The missing baryon problem is solved'.
The other worldwide team, whose lead author is Hideki Tanimura from the University of British Columbia, Canada, studied data of the thermal Sunyaev-Zel'dovich effect between ∼260,000 pairs of Luminous Red Galaxies (LRG's) taken from the Sloan Digital Sky Survey.
'If this factor is included, our findings are very consistent with the other group.
Ralph Kraft, from the Harvard-Smithsonian Center for Astrophysics in MA, said the findings help align the discrepancy between observations and simulations of the universe.
Dr. Ralph Kraft, an astrophysicist from the Harvard-Smithsonian Center of Astrophysics at MA in US State, explained that, "Everybody sort of knows that it has to be there, but this is the first time that somebody - two different groups, no less - has come up with a definitive detection".