Abstract
Abstract
We investigate how the photon polarization is affected by the interaction with axion-like particles (ALPs) in the rotating magnetic field of a neutron star (NS). Using quantum Boltzmann equations the study demonstrates that the periodic magnetic field of millisecond NSs enhances the interaction of photons with ALPs and creates a circular polarization on them. A binary system including an NS and a companion star could serve as a probe. When the NS is in front of the companion star with respect to the earth observer, there is a circular polarization on the previously linearly polarized photons as a result of the interaction with ALPs there. After a half-binary period, the companion star passes in front of the NS, and the circular polarization of photons disappears and changes to linear. The excluded parameter space for a millisecond NS with 300 Hz rotating frequency, highlights the coupling constant of 1.7 × 10-11 GeV-1 ≤ gaγγ
≤ 1.6 × 10-3 GeV-1 for the ALP masses in the range of 7 × 10-12 eV ≤ ma
≤ 1.5 × 103 eV.