Orbit-induced Spin Precession as a Possible Origin for Periodicity in Periodically Repeating Fast Radio Bursts

FRB 180916.J0158+65 has been found to repeatedly emit fast radio bursts with a period of roughly 16 days. We propose that such periodicity comes from the orbit-induced spin precession of the emitter, which we assume to be a neutron star. Depending on the mass of the companion, the binary period ranges from several hundreds to thousands of seconds. Such tight binaries have relatively short lifetimes, and they are not likely to be products of gravitational decay from wide binaries. We comment on the relation of such binaries to GW190425 and the possibility of detecting them with LISA and LIGO.