Abstract
The diffusion coefficients around the pulsar \(\gamma\)-ray halos are highly suppressed compared with the value in the interstellar medium. It is suggested in the literature that the \(\gamma\)-ray halos can be explained by a ballistic-diffusive (BD) propagation without slow diffusion. However, our calculation shows that the BD propagation cannot account for the \(\gamma\)-ray halo profile well. Furthermore, the transfer efficiency of the pulsar spin-down energy to the high-energy electrons and positrons is even larger than 1 in the BD scenario. Therefore, slow diffusion is necessary to account for the pulsar \(\gamma\)-ray halos. Taking the slow diffusion into account, the contribution of positron flux originating from nearby pulsars to the AMS-02 data is reexamined. We may also expect a slow diffusion disk of the Milky Way as many such slow diffusion regions exist. The positron contribution to the AMS-02 data from dark matter annihilation in the new propagation model is also reexamined. We find that the dark matter scenario satisfies all the \(\gamma\)-ray limits in the new propagation model.