Cosmic ray transport in the proximity of pulsars and the formation of gamma-ray halos

The detection of an extended multi-TeV gamma ray emission around the Geminga and Monogem pulsars by the HAWC collaboration provides a unique tool to investigate the transport properties of cosmic rays in the turbulent magnetized interstellar medium. Previous analyses of such emission in the framework of pure isotropic diffusion lead to infer a suppression of the diffusion coefficient in the pulsars region by at least two orders of magnitude compared to typical values found in models of Galactic cosmic ray propagation. In this work, we investigate the transition from the ballistic to the diffusive regime, and show that, when such transition is taken into account, a good fit to the HAWC 𝛾−ray data around Geminga and Monogem is obtained with typical values of the interstellar diffusion coefficient.