Reconciling the 16.35-day period of FRB 20180916B with jet precession

TL;DR

This paper explores two models of jet precession to explain the 16.35-day periodic activity of FRB 180916, concluding that tidal forces in a neutron star/white dwarf binary can account for the observed period.

Contribution

It introduces a tidal force-driven jet precession model involving a neutron star/white dwarf binary to explain FRB 180916's periodicity, addressing limitations of the disk-driven model.

Findings

Tidal force-driven precession periods range from days to hundreds of days.

The duration of FRB activity in the binary system can last several thousand years.

Disk-driven precession requires implausibly low viscosity parameters.

Abstract

A repeating fast radio burst (FRB), FRB 20180916B (hereafter FRB 180916), was reported to have a 16.35-day period. This period might be related to a precession period. In this paper, we investigate two precession models to explain the periodic activity of FRB 180916. In both models, the radio emission of FRB 180916 is produced by a precessing jet. For the first disk-driven jet precession model, an extremely low viscous parameter (i.e., the dimensionless viscosity parameter $\alpha \lesssim 10^{-8}$) is required to explain the precession of FRB 180916, which implies its implausibility. For the second tidal force-driven jet precession model, we consider a compact binary consists of a neutron star/black hole and a white dwarf; the white dwarf fills its Roche lobe and mass transfer occurs. Due to the misalignment between the disk and orbital plane, the tidal force of the white dwarf can drive jet precession. We show that the relevant precession periods are several days to hundreds of days, depending on the specific accretion rates and component masses. The duration of FRB 180916 generation in the binary with extremely high accretion rate will be several thousand years.