Philipp Mertsch – Cosmic ray anisotropies: unravelling sources and transport

The arrival directions of Galactic cosmic rays are highly isotropic. This is expected from the presence of turbulent magnetic fields in our Galactic environment that repeatedly scatter charged cosmic rays during propagation. However, various cosmic ray observatories have identified weak anisotropies of various angular sizes and with relative intensities of up to a level of 1 part in 1000. On large scales, the observed amplitude is much smaller than predicted by models of cosmic ray diffusion. On small scales, the appearance of small-scale anisotropies down to an angular size of 10 degrees is surprising. I will argue that taking into account the intermittent nature of the turbulent magnetic field could resolve these issues. The small-scale anisotropies in particular reflect the turbulent magnetic field in our Galactic neighbourhood and provide a new handle for testing its structure.