Prof Lars Bergström


Description

I started as a particle physicist, taking a doctor's degree in theoretical physics at the Royal Institute of Technology. After 2 years as a theory Fellow at CERN, I returned to Sweden and became a researcher at Stockholm University. At the end of the 1980's I became more and more interested in cosmology and astroparticle physics, and wrote several papers on the dark matter problem. I had the first position in astroparticle physics in Sweden, 1992-98, paid by the Swedish Natural Science Research Council. With Ariel Goobar, who had just returned from UC Berkeley, I wrote a university-level textbook "Cosmology and Particle Astrophysics (Praxis/Wiley 1998, updated edition on Praxis/Springer 2004). Today, I am project leader for the Linnaeus grant The Oskar Klein Centre at the Department of Physics, Stockholm University.

What is astroparticle physics? Here is a short introduction:

In recent years, the connections between the science of the smallest constituents of the Universe (particles or perhaps strings) and the science of the largest structures in the Universe - including the Universe itself and its evolution, cosmology - have become ever stronger. There are many reasons for this. One is the fact that the current cosmological ``standard model'' - the Big Bang model - implies that the earliest stages of the Universe (the first fractions of a second) were dominated by the particles (quarks, leptons and force carriers) whose properties can only be intensively studied at accelerators. Another reason is that with the help of particles such as gamma rays, neutrinos, protons positrons and antiprotons, there is a possibility to learn more about many astrophysical processes which have traditionally only been studied by low-energy electromagnetic radiation (light and radio waves). Using the energetic cosmic rays that come to the Earth from outer space new information about particles and their interactions can also be obtained. One example is the discovery of a non-zero mass of the neutrino by studying cosmic ray induced muon and electron neutrinos.

However, the most interesting connection between the smallest and the largest, and the area where I have spent most of my research, concerns the mysterious component, called dark matter, which is felt by gravity and which outweighs ordinary matter by a factor of 6 in the universe. Still, we do not know what it is! The most promising candidate for dark matter is perhaps the lightest supersymmetric particle, a hypothetical particle that is searched for at the new accelerator LHC at CERN at the moment. Using the fact that two such particles, if they encounter each other anywhere in the Galaxy, will destroy each other - annihilate - and give rise to cosmic rays, we may deduce the nature of the dark matter particle. In Stockholm, there are several experiments with the potential of discovering dark matter, ATLAS at LHC and Fermi, HESS, IceCube and Pamela studying cosmic gamma rays, neutrinos and antimatter.



Projects

Linnaeus grant: The CosmoParticle Collaboration (CPC)
01/07/2008 - 30/06/2018
The CosmoParticle Collaboration (CPC) aims at using the combined skills of particle physicists, astrophysicists and cosmologists to adress fundamental questions concerning dark matter, dark energy and extreme objects in the universe. The current collaboration consists of 23 peopl...

Theoretical astroparticle physics
01/03/2013 - 31/12/2017
Mörk Materia: Ett steg närmare lösningen? Att det finns okänd, mörk materia som påverkar sin omgivning med sin gravitation har varit känt sedan 1930-talet när Fritz Zwicky noterade att galaxerna i galaxhopen Coma rör sig för snab...

Theoretical Astroparticle Physics
01/01/2010 - 31/12/2012
This project deals with one of the outstanding questions in physics at the moment: What is it that constitutes the dark matter that seems to pervade the Universe? To attempt a solution of this question, we will use data currently being collected in instruments that we have helped...

Theoretical Astroparticle Physics
01/01/2007 - 31/12/2009
It is impossible to explain the behaviour of the Universe without two major, but completely unknown, constituents: dark matter and dark energy. This is inferred from the largest scales, as seen in the cosmic microwave background, to galactic scales and smaller. This project has a...

Overexpression of differentiating factors in neural stem cells in vivo
01/01/2005 - 31/12/2008
By overexpressing genes in the neural stem cells in vivo, the cells response to these factors can be investigated. This method is well suited for investigating the impact of a certain factor on early neural development or on stem cell function in the adult. Enhancer sequences in ...


Collaborators


Last updated on 2017-16-06 at 11:14