On the resonant production of axions in a magnetar magnetosphere

The effect of a magnetized plasma on the resonant photoproduction of axions on the electromagnetic multipole components of the medium, i → f + a, has been considered. It has been shown that the axion emissivity in the resonance region, owing to various reactions involving particles of the medium, is certainly expressed in terms of the emissivity of the photon → axion transition. The number of axions produced by the equilibrium cosmic microwave background radiation in the magnetar magnetosphere has been determined. It has been shown that the resonant mechanism under consideration is inefficient for the production of cold dark mass.