Speaker
Description
Many $\gamma$-ray sources, such as supernova remnants, superbubbles, and pulsar halos, may be surrounded by regions where cosmic ray (CR) diffusion is suppressed relative to the typical galactic rate. Although these regions strongly affect CRs injected by their associated accelerators, their impact on the pre-existing CR background remains poorly understood. We have derived an analytical solution for the response of an anisotropically diffusing CR background to a spherical region with isotropically suppressed diffusion. We find that such a region can amplify the CR density gradient within it, potentially affecting $\gamma$-ray background estimates that assume a uniform CR density. A nearby slow-diffusion region (SDR) magnetically connected to Earth can also markedly reduce the observed CR dipole amplitude. If the ratio of diffusion coefficients inside and outside the region varies with CR energy, certain parameter combinations may account for the observed amplitude minimum near 150 TeV and the accompanying reversal of the right-ascension phase.
