The Impact of Accretion on FRB Radiation Mechanisms in Binary Systems: Constraints and Implications

Fast Radio Bursts (FRBs) are intense, millisecond-duration radio transients that have recently been proposed to arise from coherent radiation mechanisms within the magnetosphere of neutron stars. Observations of repeating FRBs, including periodic activity and large variations in Faraday rotation measures, suggest that these bursts may have binary system origins, with massive companion. In this work, we investigate how accretion from a massive companion influences the FRB radiation within the magnetosphere of the neutron star. Focusing on two widely accepted pulsar-like coherent radiation mechanisms, we establish the parameter space for neutron stars that allows FRB generation, even in the presence of accreted matter. Our analysis shows that coherent curvature radiation is only viable within a narrow range of parameters, while the magnetic reconnection mechanism operates across a broader range. In both cases, the neutron star must possess a strong magnetic field with strength $\gtrsim 10^{13}$ G. These findings at least indicate that the central engines responsible for producing observable FRBs in binary systems are indeed magnetars.