9-13 July 2012
Inferring the presence of nearby sources of cosmic rays by method of galactic propagation modelling
Presented by Mr. Driaan BISSCHOFF on 11 Jul 2012 from 08:20 to 08:40
Type: Oral Presentation
Track: Track D1 - Astrophysics
Full 3D time dependent calculations of the propagation of cosmic rays (CRs) have shown that if CRs indeed originate from SNR, transient point-like sources, the flux of the CR primary component measured at Earth depends strongly on the local source history, whereas the secondary component shows little to no variation due to nearby sources. However, due to their simplicity, steady state, rotational symmetric models (2D) of CR propagation are still widely used, although they cannot properly take into account the influence of nearby point sources, but rather assume smeared-out sources. In this study, we make use of the fact that 2D models don't describe CR primaries and secondaries equally well, to look for evidence of a nearby point source. Doing a parameter study, one may expect different best fit values looking at the primary and secondary CR components separately, as it is unlikely that the source history mimicked by the 2D models coincides with the real local source history. We adapted the 2D version of the GALPROP code to a compute-cluster environment and perform parameter studies comparing CR spectra with mainly primary and secondary CR data separately. The results obtained, together with the manner in which the 2D model handles CR sources, imply that there maybe local sources of CRs that, so far, are not being taken into account. Recommendations for further such studies are also given.
Prof. M.S. Potgieter email@example.com NWU Potchefstroom