Excesses of cosmic ray spectra from a single nearby source
AbstractGrowing evidence reveals universal hardening on various cosmic ray spectra, e.g., proton, positron, as well as antiproton fractions. Such universality may indicate they have a common origin. In this paper, we argue that these widespread excesses can be accounted for by a nearby supernova remnant surrounded by a giant molecular cloud. Secondary cosmic rays (p, e+) are produced through the collisions between the primary cosmic-ray nuclei from this supernova remnant and the molecular gas. Different from the background, which is produced by the ensemble of a large number of sources in the Milky Way, the local injected spectrum can be harder. The time-dependent transport of particles would make the propagated spectrum even harder. Under this scenario, the anomalies of both primary (p, e-) and secondary (e+, p¯/p) cosmic rays can be properly interpreted. We further show that the TeV to sub-PeV anisotropy of the proton is consistent with the observations if the local source is relatively young and lying at the anti-Galactic center direction.