Speaker
Description
The axion coupling to the photon allows for axion-photon oscillations and is governed by the coupling and background magnetic field. In astrophysical settings these oscillations possess resonant behavior while traversing the plasma of both intra and intergalactic media. We demonstrate that a second type of resonant enhancement is possible which depends on the spatial variation $\dot{\Theta}$ of the transverse components of the coherent magnetic field with respect to the direction of propagation. This mimics a Mikheyev–Smirnov–Wolfenstein (MSW)-like shift in the plasma resonance and affects the parameter space of axion and Axion-Like-Particle (ALP) detection from astrophysical sources. We investigate this effect for the various models of the coherent galactic magnetic field of the Milky Way and emphasize the need to consider the full structure of the galactic magnetic field for setting astrophysical limits on ALPs.