UKZN Astrophysicist Searches for Missing Matter
A group of astrophysicists, including UKZN’s Dr Yin-Zhe Ma, may have solved a long standing problem in cosmology, which is the study of how the Universe expands. Dr Ma is a new member of UKZN’s Astrophysics and Cosmology Research Unit (which is housed in the School of Mathematics, Statistics and Computer Science) and the School of Chemistry and Physics.
A number of telescopic observations of the Universe tell us that only 5% consists of the ordinary matter that we encounter in everyday life. The remaining 95% is made from a combination of a mysterious substance called “dark matter” and “dark energy”.
Ordinary matter is composed of baryons which are subatomic particles such as protons and neutrons that make up the things around us - like our human body, objects that we encounter in everyday life, our planet and our galaxy. However, most of the baryons in the Universe occur in the form of an intergalactic, low density gas which makes them hard to detect directly. This is known as the “missing baryon problem” in astrophysics.
By observing, through the Planck satellite telescope, the oldest radiation in the Universe which is known as the cosmic microwave background, Dr Ma and his team may have discovered the missing baryons in and around certain galaxies.
This may be deduced because the motion of gas inside and around these galaxies indicates that these regions contain roughly half of the total amount of baryons in the Universe. If the distribution of the ordinary matter in outer space is similar to that of dark matter, then it seems likely that all of the baryons will be found in and around the galaxies.
A paper describing the study has been published in Physical Review Letters, where it was highlighted as an Editor’s suggestion.