A group of astrophysicists, including new ACRU member Dr. Yin-Zhe Ma, has perhaps solved a long standing problem in cosmology.

A number of observations tell us that only 5% of the Universe is made up of the ordinary matter that we encounter in everyday life (baryons), with the remaining 95% being made from a combination of the mysterious ‘dark matter’ and ‘dark energy’. However, locating even the 5% of ordinary matter that is expected to exist has been a challenge – this is referred to as the “missing baryons” problem.

Using observations of the cosmic microwave background, taken with the Planck satellite, in the directions of galaxies identified in the Sloan Digital Sky Survey, the missing baryons may have been found. The motion of gas inside and around the galaxies indicates that these regions contain roughly half of the total amount of baryons in the Universe. If the spatial distribution of the ordinary matter follows that of the dark matter, then it seems likely that all of the baryons will be found in and around the galaxies.

The paper describing the study is published in Physical Review Letters and is highlighted as an Editor’s suggestion.