BEXCO - Room F(201/202/203/204)
[CRI007] Research on element dependence of cosmic ray large-scale anisotropy with the ARGO-YBJ experiment
The sidereal time cosmic ray large-scale anisotropy with amplitude of 10−4–10−3 has been firmly detected by a number of experiments from sub-TeV to PeV. The angular phase is approximately stable for energies below 100 TeV, while the amplitude increases with energy, reaching the maximum around 10 TeV. Different models have been proposed to explain the origin of the anisotropy, concerning different aspects of cosmic ray physics, from the sources of cosmic rays to the propagation to the Earth. Some models consider the anisotropy due to the spatial distribution of sources, as the presence of a nearby strong source, while other interpretations concern the structure of the Galactic and interplanetary magnetic fields. No matter which model, the magnetic field must play an important role, and this would produce differences in the anisotropy among the cosmic ray elements. Therefore, an element dependence measurement will provide important clues to test current models. In this work, we use the ARGO-YBJ data collected from 2008 to 2009 to study the element dependence of cosmic ray large-scale anisotropy. The ARGO-YBJ data are selected with two distinct criteria, which differ for their cosmic ray element ratio. Then the models are tested by comparing the anisotropies of the two data samples. The implication on the anisotropy origin is also discussed.