Picard — a Cosmic Ray Propagation Code

Picard is a Galactic cosmic ray propagatio code developed at Innsbruck University. The purpose of the code is the numerical solution of the cosmic ray transport equations with a focus on the observed cosmic ray spectra at Earth and the gamma-ray emission resulting from the interaction of the Galactic cosmic rays with the interstellar medium. The features of Picard include:
  • Compatibility to Galdef parameter files
  • MPI-parallel implementation -- allowing computation on distributed memory computers
  • Efficient computation of spatially 3D CR distributions
  • Computation of ensuing gamma-ray emission
  • Possibility of fully anisotropic spatial diffusion
One of the important destinctions of Picard is the numerical scheme for the solution of the cosmic ray transport equation:
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For this transport equation mostly steady state solutions for a given cosmic ray source distribution are investigated. The majority of other Galactic cosmic ray propagation codes, however, use some time-integration procedure to determine such a steady state solution. While the implementation of a time-integrating scheme for the transport equation is relatively simple, such a scheme is not very efficient and it becomes necessary to determine whether a steady-state solution has been found.
Therefore, Picard uses an alternative method, where a steady-state solution is computed directly. While the implementation of the corresponding scheme is more difficult than for a time-integration scheme, it turns to be numerically more efficient than other schemes. Thus, Picard allows for very high resolution, spatially 3D simulations, by which physical effects can be investigated that are inaccessible at lower spatial resolution. As a first study, we investigated the effects of a cosmic ray source distribution restriced to the vicinity of the Galactic spiral arms, as is discussed in the cosmic ray section of this site.
Picard is a relatively new code that is continuously enhanced and improved. If you are interested in more details, see the article Kissmann (2014) or contact me directly via e-mail. We continuously offer BSc and MSc theses in the context of the Picard code for interested students. Possible theses include both numerical development of the code and application to specific cosmic ray propagation problems.
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