Sudden discharge of young charged magnetars as a new model for FRBs

Abstract

ABSTRACT We propose a new model for Fast Radio Bursts (FRBs) based on a sudden discharge of a charged young magnetar, caused by the short falling time-scale of oppositely charged particles on to the magnetar. In this scenario, curvature radiation is emitted by particles accelerated at relativistic by the strong electric fields produced by the disconnection and the subsequent reconnection of the magnetic field lines, a process triggered by the sudden discharge. We modelled the magnetars as charged neutron stars in the static approximation using the exterior metric by the Reissner–Nordström. We also adopted an electrical charge distribution proportional to the mass-energy density, although our results are not strongly sensitive to the specific star’s charge distribution, only to the total charge. Our calculations show that the discharge and emission time-scales are several milliseconds, compatible with the FRB phenomena for magnetars with a total charge of ∼1020 C and mass and radius in the range of 1.5–3.0 M⊙ and 10–45 km, respectively. Furthermore, the calculated total emitted power of a coherent pulse is $P_{\mathrm{ tot}}\sim 10^{42-43} \, \mathrm{erg\, s}^{-1}$, and the frequency range and time-scale are also consistent with FRBs astronomical observations. Finally, if the magnetar does not collapse after the discharge, the existence of FRB repeater sources cannot rule out the existence of a blast repetition after the time needed to magnetosphere recharges and produce a new discharge.