Monogem’s Contribution to the Galactic Cosmic-Ray Spectrum

The study of local cosmic-ray (CR) sources is crucial for understanding the anomalous features observed in the energy spectra of CR nuclei, as well as the reversal of both the amplitude and phase of CR anisotropy around 100 TeV. Among the candidate sources, Geminga and Monogem are frequently considered primary contributors to the observed CR spectrum. However, the precise role of Monogem remains an open question. In this work, we conduct a detailed reanalysis of the contributions from these two local sources using a three-dimensional, spatially dependent propagation model that explicitly accounts for the halo structure of CR sources. Our findings indicate that within this framework, CRs originating from Monogem are largely prevented from reaching Earth due to obstruction by the Geminga pulsar halo. Consequently, Geminga emerges as the dominant contributor to the local CR spectrum.