Repeating fast radio bursts with high burst rates by plate collisions in neutron star crusts

Abstract

Some repeating fast radio burst (FRB) sources show high burst rates, and the physical origin is still unknown. Outstandingly, the first repeater FRB 121102 appears extremely high burst rate with the maximum value reaching 122 h−1 or even higher. In this work, we propose that the high burst rate of an FRB repeater may be due to plate collisions in the crust of young neutron stars (NSs). In the crust of an NS, vortex lines are pinned to the lattice nuclei. When the relative angular velocity between the superfluid neutrons and the NS lattices is nonzero, a pinned force will act on the vortex lines, which will cause the lattice displacement and the strain on the NS crust growing. With the spin evolution, the crustal strain reaches a critical value, then the crust may crack into plates, and each of plates will collide with its adjacent ones. The Aflvén wave could be launched by the plate collisions and further produce FRBs. In this scenario, the predicted burst rate can reach ∼770 h−1 for an NS with the magnetic field of 1013 G and the spin period of 0.01 s. We further apply this model to FRB 121102, and predict the waiting time and energy distribution to be $P(t_{\mathrm{w}}) \propto t_{\text{w}}^{\alpha _{t_{\text{w}}}}$ with $\alpha _{t_{\text{w}}} \simeq -1.75$ and $N(E)\text{d}E \propto E^{\alpha _{E}}\text{d}E$ with αE ≃ −1.67, respectively. These properties are consistent with the observations of FRB 121102.

Repeating Fast Radio Bursts Reveal Memory from Minutes to an Hour

“…In the framework of the magnetar model, zones of magnetic stress are generated in the crust due to magnetic field evolution and field reconfiguration through Hall drift and ohmic dissipation (Ruderman et al 1998). When the magnetic stresses exceed a critical threshold, frequent crustal fractures will occur, which can produce repeating FRBs (Suvorov & Kokkotas 2019;Lu et al 2020;Li et al 2022). In fracture processes, the crustal strain redistributes through neighbor tectonic interactions, which can trigger subsequent bursts.…”

A giant glitch from the magnetar SGR J1935+2154 before FRB 200428

“…After the glitch, the motion of the core superfluid neutron vortices in the direction perpendicular to the spin axis during the spin-down relaxation phase of the glitch would alter the core magnetic field, which would result in the movement of the neutron star crust and the change in the surface magnetic field (Ruderman et al 1998). Crustquakes are expected if the solid crust does not plastically adjust to the less-oblate equilibrium shape required by the pulsar's spin-down or if the magnetic stress exceeds the shear modulus (Baym & Pines 1971;Thompson & Duncan 1995;Perna & Pons 2011;Li et al 2022). Crustal fracturing produces Alfvén waves and then generates X-ray bursts (Thompson & Duncan 1995).…”

“…However, the mechanism triggering FRB 200428 is not well understood yet. It is widely suggested that FRBs are generated by the magnetospheric activities of magnetars, either triggered internally (Yang & Zhang 2018;Lyubarsky 2020a;Lu et al 2020;Yang & Zhang 2021;Wang et al 2021;Li et al 2022) or externally (Zhang 2017Geng et al 2021;Dai 2020). Recently, Younes et al (2022) report that SGR J1935+2154 experienced one spin-down glitch, followed by FRB-like bursts and a pulsed radio episode.…”

Repeating fast radio bursts reveal memory from minutes to an hour

“…In the framework of the magnetar model, zones of magnetic stress are generated in the crust due to magnetic field evolution and field reconfiguration through Hall drift and Ohmic dissipation (Ruderman et al 1998). When the magnetic stresses exceed a critical threshold, frequent crustal fractures will occur, which can produce repeating FRBs (Suvorov & Kokkotas 2019;Lu et al 2020;Li et al 2022). In fracture processes, the crustal strain redistributes through neighbour tectonic interactions, which can trigger subsequent bursts.…”

“…One possible trigger mechanism is the crustal failure of a neutron star, favoring emission from the stellar magnetosphere (Suvorov & Kokkotas 2019;Lu et al 2020;Li et al 2022). FRB 20201124A…”