Search for energetic cosmic axions utilizing terrestrial/celestial magnetic fields

Abstract

Orbiting γ-detectors combined with the external magnetic field of the Earth or the Sun can work parasitically as cosmic axion telescopes. The relatively short field lengths allow the axion-to-photon conversion to be coherent for m axion∼10 −4 eV, if the axion kinetic energy is above ∼500 keV (Earth's field), or ∼50 MeV (Sun's field), allowing thus searches for axions from e + e − annihilations, M1 transitions, supernova explosions, etc. With a detector angular resolution of ∼1°, a more efficient sky survey for energetic cosmic axions passing through the Sun can be performed. The axion signal will be an excess in γ-rays coming either from an active celestial place behind the Sun, e.g. the Galactic Center, or, from any other direction in the sky being associated with a violent astrophysical event, e.g. a supernova. Earth bound detectors are also of potential interest. Similar to the axion searches in accelerator beam dump experiments, axions or other axion-like particles might be created during the interaction of the cosmic radiation with the Sun; the coherent axion-to-photon conversion inside Sun's external magnetic field is beyond the reach of man made magnets. The axion scenario also applies to other stars or binary systems in the Universe, in particular to those with superstrong magnetic/electric fields.