Gary Mamon's Research Topics: Cosmology

Cosmology is the study of the Universe as a whole. The fundamental questions relate to the composition of the Universe. Several astronomical techniques converge to the following picture: 85% of the matter of the Universe is not made of the atomic nuclei that compose our bodies, our planet and our Sun. We call this dark matter. It is somewhat embarassing that we have not yet been able to detect the particles that constitute this dark matter, and that we have no strong clues on its mass or characteristics.

Perhaps even more surprising is that the expansion of the Universe is not declerating, as expected from the attractive nature of gravity, but is accelerating instead (this discovery in 1998 by two teams led by Saul Perlmutter on one hand and Brian Schmidt and Adam Riess on the other, led these three astronomers to be awarded the Nobel Prize for Physics in 2011). The nature of this dark energy is completely unknown.

Gary Mamon has been the first to obtain the currently favored value of Ωm=0.3 for the density parameter of the Universe, using groups of galaxies as a tracer, through two techniques:

  1. Obtaining the group masses by correcting the masses obtained via the virial theorem by the collapsing nature of the groups catalogued at the time (Mamon 1993);
  2. Determining the group masses by applying hydrostatic equilibrium to a group of galaxies with iintragroup hot gas emitting in the X rays (Henriksen & Mamon 1994).

Gary Mamon's important papers on the topic are: