Astronomers have determined that dark energy accounts for around 69% of the total matter-energy density of the Universe. This leaves the remaining 31% to normal matter (such as stars, galaxies, and atoms) and dark matter, a mysterious form of matter that affects the Universe through gravity.
Dark energy is an unknown force responsible for the accelerating expansion of the Universe, while dark matter is a gravitational force that cannot be explained by current theories. Scientists believe that around 80% of the matter in the Universe is made up of dark matter, with the rest being regular or ‘baryonic’ matter.
To measure the matter-energy density of the Universe, astronomers used clusters of galaxies. By comparing the number and mass of galaxies in a cluster with numerical simulations, scientists can calculate the proportions of matter and energy. This method is based on the fact that galaxy clusters are formed from matter that has collapsed over billions of years under gravity.
The researchers used a technique called GalWeight to estimate the mass of galaxy clusters in their database. They then performed simulations with different proportions of dark energy and matter and found that a Universe consisting of 31% matter best matched the observed galaxy clusters. This measurement is in agreement with previous studies and other measurements of the matter-energy density.
This research provides valuable insights into the composition of the Universe and helps scientists understand the nature of dark energy. It also enhances our understanding of the expansion of the Universe, with potential implications for its future.
Sources: The Astrophysical Journal