Neutron Stars and FRBs

Because Neutron Stars (NSs) have large dipolar magnetic fields, they emit electromagnetic radiation as they rotate, and this emission exerts a torque on the NS which works to align the magnetic dipole axis with the NS's spin axis. This made the observation of Lyne et al. (2013) puzzling, who found the inclination between the dipole and spin axis's (magnetic inclination angle) increasing with time for the Crab pulsar. With Prof. Dong Lai, I showed this could be explained by free and "inertial" precession from the Crab Pulsar's rigid bulge and magnetic field's inertia, causing the magnetic inclination angle to increase over short timescales, and decrease over long timescales. We also showed free and inertial precession were dynamically indistinguishable.

Recently, the CHIME/FRB collaboration has reported a 16 day periodicity on the radio bursts emitted by FRB 180916. With Prof. Dong Lai, I showed FRB 180916's periodicity can be explained by emission from a magnetar undergoing free/inertial precession. With Dr. Dongzi Li, we showed how the burst activity window becomes narrower and earlier at higher frequencies, due to curvature radiation from a precessing magnetar. Our work is currently one of the leading theories to explain "periodic Fast Radio Bursts" (see review by Prof. Bing Zhang)


Dongzi Li & J. J. Zanazzi, Emission Properties of Periodic Fast Radio Bursts from the Motion of Magnetars: Testing Dynamical Models. 2021, ApJL, 909, L25. PDF

J. J. Zanazzi & Dong Lai, Periodic Fast Radio Bursts with Neutron Star Free Precession. 2020, ApJL, 892, L15. PDF

J. J. Zanazzi & Dong Lai, Electromagnetic Torques, Precession, and Magnetic Inclination Evolution of Magnetic Inclination of Pulsars. 2015, MNRAS, 451, 695. PDF