Dark matter

The galaxy UGC 9391 seen by the Hubble Space Telescope. Cepheid variable are in red circles, a type Ia supernova is marked by a blue cross (Image NASA, ESA, and A. Riess (STScI/JHU))

An article accepted for publication in “The Astrophysical Journal” describes a research based on observations made with the Hubble Space Telescope that suggests that the universe is expanding at a faster rate than expected. A team of astronomers led by Nobel laureate Adam Riess measured the distance of stars in nineteen galaxies with the best accuracy ever achieved to obtain this surprising result.

A portion of space simulated by the Illustris project showing the distribution of dark matter (Image courtesy Markus Haider / Illustris collaboration)

An article published in the journal “Monthly Notices of the Royal Astronomical Society” describes a research on the distribution of matter in the universe. According to the results 20% of ordinary matter is contained in the so-called cosmic voids and galaxies are only 1/500th of the volume of the universe. A team led by Dr Markus Haider of the Institute of Astro and Particle Physics at the University of Innsbruck in Austria, has used simulations of the Illustris project to reach these conclusions.

The Abell 1689 galaxy cluster

An article published in the journal “Physical Review Letters” offers clues about the link between the internal structure of a galaxy cluster and the dark matter environment surrounding it. The study of dark matter is complex because it can only be done indirectly due to the fact that we can’t detect it directly. Until now, scientists believed that the greater the mass of a cluster the greater the amount of dark matter in its environment. This new research suggests that things are more complicated.