Particle Astrophysics and Cosmology
Research in particle astrophysics at the University of
Saskatchewan concentrates on two major puzzles
of contemporary physics:
The Dark Matter Problem:
Astrophysical observations indicate that only about
10% of the matter in galaxies and galaxy clusters
is composed of ordinary matter
(essentially protons, neutrons, electrons and their bound states), but
the rest of the matter bound in large scale structures in the universe
must be composed of particles which cannot be produced in accelerators
Since this matter component reveals itself only through its gravitational
interactions, but does not produce luminous stars,
it is denoted as dark matter.
One area of research that we pursue in this field is the investigation
of particle physics candidates predicted by string theory and other extensions
of the Standard Model of Particle Physics. We do this by calculating
couplings, lifetimes and cosmic abundances of particle dark matter candidates,
to test whether any of the candidates predicted by extensions
of the standard model matches the requirements imposed by astrophysical
The Origin of Ultra-high Energy Cosmic Rays:
Over the last decades several experiments observed cosmic rays of extremely
high energies E> 1011 GeV. The northern hemisphere is hit by such
extremely high energetic rays with a frequency of 1 event per
100 km2 per year, but reliable results from the southern
will only become available when the southern site of
the Pierre Auger observatory in
Argentina becomes fully operational.
This is important, because both the galactic center and the closest
galaxy cluster (the Virgo cluster) are only visible from the southern
The origin of these high-energetic cosmic rays is a puzzle for several
In collaboration with colleagues from Fermilab
I recently made the proposal that annihilation of extremely heavy dark matter
particles can generate the ultra-high energy cosmic rays.
- Charged particles at these high energies loose their energy very
efficiently through scattering with cosmic background photons.
Therefore the sources of these extremely high energy cosmic rays cannot
be extremely far away, which makes it likely that the sources should be located
within our galaxy.
- No astrophysical acceleration mechanisms are known that could accelerate
particles to these high energies.
- The arrival directions of these high-energetic cosmic rays do not point at
any visible stellar sources.
This proposal is attractive for several reasons:
As a graduate student in my group you can participate in our ongoing
efforts to unravel the mystery of the ultrahigh energy cosmic rays.
- It is known that the galactic halo is mostly
composed of dark matter;
- annihilation does not have to invoke any unknown
acceleration mechanism to generate the cosmic rays, but instead uses
of rest mass energy into cosmic rays;
- no visible stellar sources are required.
For more information please see my web page
or contact me by