Revisiting the neutron star-white dwarf binary model of FRB 121102

Abstract

Fast radio bursts (FRBs) are intense radio pulses with millisecond-duration from the sky, the physical origin of which remains a mystery. A compact binary model consisting of a magnetic white dwarf and a neutron star with strong bipolar magnetic field may be responsible for the central engine of repeating FRBs . The scenario is that, when the white dwarf fills its Roche lobe, mass transfer will occur through the inner Lagrange point, and the white dwarf may be kicked away after a mass transfer process. For the only known repeating burst source, i.e., FRB 121102, 41 repeating events have been detected. With the known redshift and the 41 repeating bursts, we revisit the neutron star-white dwarf binary model and confirm that such an intermittent Roche-lobe overflow mechanism can be responsible for the observed repeating behavior of FRB 121102. In addition, no correlation exists between the time interval of two adjacent bursts and the fluence of the subsequent burst, which agrees with the Roche-lobe overflow mechanism.