Effects of Gravitational-wave Radiation of Eccentric Neutron Star–White Dwarf Binaries on the Periodic Activity of Fast Radio Burst Sources

We revisit the eccentric neutron star (NS)-white dwarf (WD) binary model for periodic activity of fast radio burst (FRB) sources, by including effects gravitational wave (GW) radiation. In this model, WD fills its Roche lobe at periastron and mass transfer occurs from to NS. The accreted materials can be fragmented arrive NS episodically, resulting in multiple bursts through curvature Consequently, may kicked away owing conservation angular momentum. To initiate next transfer, has refill GW scenario, whether show up relies on three timescales, i.e., orbital period $P_{\rm orb}$, timescale $T_{\rm GW}$ refilled, time span frag}$ all episodic events corresponding each process. Only when two conditions GW} \gtrsim P_{\rm orb}$ frag} < are both satisfied, will manifest itself should equal orb}$. spirit, is more likely relatively long periods ($P_{\rm orb} \gtrsim$ several days). Thus, it reasonable that FRBs 180916 121102, only sources having been claimed activity, correspond periods.