Found the missing half of the Universe


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".

The elusive "missing" half of the universe's observable matter has been found by two teams of astronomers in a world first.

So there was comprehensible delirium when it transpired that two distinct teams of researchers may have discovered this "missing" baryonic matter.

The teams' work focused on the universe's ordinary matter, matter composed of protons, neutrons and electrons, as opposed to mysterious dark matter, which make up most of the known universe. Finding the remaining 95 percent of baryons has since been one of the major challenges in modern cosmology. But scientist felt that importance of detecting these missing matter or filament to know about the formation of the Universe and what keeps the galaxies intact.

However, because the gas is relatively low temperature (around 10 - 10K) and is of low density, previous attempts to observe it via X-ray emission or absorption in quasar spectra have proven hard.

Previous observations in space had not picked the matter up because the gas is tenuous and not hot enough for X-ray telescopes. Scientists have been faced with this cosmological problem for many years-there is a huge imbalance between how much we see and how much our models say should be there.

While scientists had previously speculated the baryon gas existed, the two groups set out to definitely observe the threads of evasive particles.

The papers released as part of these discoveries have yet to be peer-reviewed, however with both groups finding a similar conclusion to their analysis, it is likely that between them, these teams have helped solve the mystery of where all the missing mass has been hiding.

Both teams took advantage of a phenomenon called the Sunyaev-Zel'dovich effect that occurs when light left over from the big bang passes through hot gas. As this light moves through hot gas, some of it scatters, leaving a patch in the CMB. Because the tendrils of gas between galaxies are so diffuse, the dim blotches they cause are far too slight to be seen directly on Planck's map. Tanimura's group found they were nearly three times denser than the mean for normal matter in the universe, and de Graaf's group found they were six times denser - confirmation that the gas in these areas is dense enough to form filaments. However, there is an abstruse problem of missing baryon particles.

'We expect some differences because we are looking at filaments at different distances, ' Dr Tanimura told New Scientist.