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

Abstract

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

One-off and Repeating Fast Radio Bursts: A Statistical Analysis

“…Some repeaters with more than 20 bursts recorded by CHIME were not found to have any periodic activity, e.g., FRBs 20180814A (22 bursts), 20190303A (27 bursts), and 20201124A (34 bursts). The differences in periodicity of repeating FRBs might indicate that the repeaters could have different groups, i.e., the periodic repeaters and the aperiodic repeaters (e.g., Katz 2017;Lin et al 2022).…”

Repeating Ultraluminous X-Ray Bursts and Repeating Fast Radio Bursts: A Possible Association?

“…In our previous studies, the NS-WD binary model with super-Eddington accretion rates has been proposed to explain the repeating FRBs. In that model, the repeating FRBs can be explained as the result of the magnetic reconnection when the accreted magnetized materials approach the NS surface (Gu et al 2016(Gu et al , 2020Lin et al 2022), or the radio radiations of the narrowly collimated jet (Chen et al 2021). FRBs are millisecond-duration radio bursts with the isotropic equivalent luminosities of ∼10 38-42 erg s −1 (for reviews, see Cordes & Chatterjee 2019;Petroff et al 2019).…”