• cosmic rays
• e+ and e- propagation models
• numerical simulations
• AMS-02
• PAMELA
• positron extra component

While traveling through the Galaxy, then, CRs undergo a random walk due to the random component of the Galactic Magnetic Field, thus their motion can be described by a diffusion equation.
In this work, I will be focusing on electrons and positrons propagation. I analyzed different models for CRs propagation, bringing forth simulations with DRAGON numerical code. Using this code in 3D mode, we were able to test these model in a new, more accurate way, also implementing a realistic distribution for CRs sources.
I simulated propagation of Boron and Carbon CRs components to set some propagation parameters for each model, then I verified that simulated protons spectra are compatible with those observed by AMS-02 and PAMELA.
I also tested some low energy effect on propagation, i.e. the effect of varying the Diffusive Halo Height, and the Alfvén velocity. We treated solar modulation with a new simulation code, HelioProp.
I verified that simulated electrons and positrons spectra are compatible with those observed by AMS-02 and PAMELA, also taking into consideration 2008 PAMELA results on the positron anomaly.
However in, the high-energy region of these spectra shows features that can not be reproduces under the hypothesis that positrons are only secondary product of CRs spallation in the ISM. To account for these features I analyzed two different scenarios proposed to explain the phenomenon: an astrophysical scenario, in which nearby Pulsars and SuperNova Remnants are called to provide the required high energy component, and a Dark Matter one, in which the annihilation of TeV-mass Dark Matter particles results in high energy positrons and electrons.
I will show that an Astrophysical scenario can provide quite easily the high energy component required to reproduce the observed absolute spectra and the positron ratio. Dark matter scenario, instead, can explain the aforementioned high energy features only under some extreme condition, especially concerning the required annihilation cross section.