Research in the Astroparticle Physics Group at NTNU


  • Supernova neutrinos
    A supernova (SN) core is approximately a blackbody source for a huge neutrino burst of all flavors. In detail, however, there are differences between the fluxes and spectral energies of ν_e, anti-ν_e, and ν_x. Therefore, one may be able to discover neutrino oscillation effects in a future SN neutrino signal. For example, one may hope to distinguish between the normal and inverted neutrino mass hierarchy, one of the important remaining questions in the area of neutrino physics.
    Of most importance for astrophysics is the information carried by the neutrino signal about the details of the explosion mechanism deep inside the SN core that is otherwise not accessible. For instance, the passage of shock waves through the region of resonant neutrino flavor conversion allows one to perform a detailed tomography of the SN interior.

    Supernova shocks:
    The movie in avi format shows a forward and a reverse shock front passing through the region of "atmospheric" resonant neutrino oscillations (green band) on the left together with the survival probability of a anti-ν_e for large θ_13. On the left the (uninteresting) first image 1 sec after core bounce is shown. For details see
    R. Tomas, M. Kachelrieß, G. Raffelt, A. Dighe, H.-T. Janka and L. Scheck,
    Neutrino signatures of supernova forward and reverse shock propagation.
    JCAP 0409, 015 (2004) [astro-ph/0407132] or here for a version with full resolution figures.



  • High-energy cosmic rays and neutrinos
    The origin of high-energy cosmic rays is more than 40 years after their first observation still unresolved. We try to answer what the cosmic ray primaries are, where and what their sources are, and how the observed energy spectrum and clustering of arrival directions of cosmic rays can be explained.
    Major obstacle for uncovering the sources of high-energy cosmic rays is their deflection in cosmic magnetic fields. A prerequisite for doing cosmic ray astronomy is therefore a better knowledge of both the galactic and the extragalactic magnetic fields. Another path is the "multi-messenger approach", i.e. the combination of data from cosmic ray, neutrino and gamma-ray experiments, that will become available in the near future. Since high-energy photons and neutrinos are produced as secondaries of hadronic interactions, their fluxes are intimately connected to the one of cosmic rays. Hence a combined interpretation of photons, neutrino and cosmic ray data will certainly improve our understanding of the cosmic high-energy radiation.
    Neutrino telescopes like     ICECUBE or air shower experiments like AUGER have also the potential to measure unknown neutrino properties and interactions. For instance, neutrino telescopes are sensitive to CP violation in the lepton sector, if they can detect Galactic "beta-beams". The latter are cosmic ray sources that produce neutrinos mainly by neutron decay.
    Finally, we investigate also actively possibilities to explain the observation of ultra-high cosmic rays with particle physics beyond the standard model or, conversely, to detect new particles or interactions observing cosmic rays.

    Extensive air showers:
    The movie shows an extensive air shower hitting several water tanks of the AUGER experiment recording Cherenkov radiation. Timing information allows one to reconstruct the arrival direction of the primary; the relative density of electrons (green) and muons (red) as function of the core distance is connected to the type of the primary.



  • Hypothetical particles and their role in astrophysics and cosmology:
  • Dark Matter candidates:
    New models of dark matter candidates are developed and observational consequences are worked out. Comparisons with experimental data are used to constrain the interaction/properties of such particles.
  • Small-scale structure of dark matter:
    A natural consequence of the hierarchical model of structure formation is the clumpiness of dark matter (DM). Signature of DM clumps is the enhanced signal from annihilating DM particles; an understanding of the size of this enhancement is crucial for the interpretation of the result from neutrino and γ-ray experiments like ICECUBE or MAGIC.

    Milky Way in gamma-rays:
    The picture shows the gamma-ray sky as seen by the EGRET experiment. Partly, especially outside the galactic plane, gamma-rays might originate from annihilations of dark matter particles.



  • Phase Diagram of QCD

  • back the homepage of the astroparticle physics group

    Last up-date: 16. Nov. 2005 by Michael Kachelrieß