Colloquium on Nov. 5, 2020

Binary Neutron Star Mergers behind Mysterious Fast Radio Bursts?

Speaker: Shotaro Yamasaki (Hebrew University)

Venue: Video Conference

Time: 15:00 PM, Thursday, Nov. 5, 2020

Abstract:

Fast radio bursts (FRBs) are millisecond-duration radio bursts discovered in 2007 whose physical origin is baffling astrophysicists. In this talk, I will review the observational properties of FRBs and borrow our wisdom in understanding binary neutron star (BNS) mergers to speculate how these mysterious bursts are generated in our Universe.  Most of FRBs do not show evidence for repetition and such non-repeating FRBs may be explained by an extreme pulsar-like emission expected at the time when BNSs merge. By using numerical-relativity simulations, we examined this possibility and found that there is a time window of about 1 ms after the merger when an FRB can be produced by the enhanced rotation of each NS without suffering from the absorption due to ejecta.  Moreover, we show that a recently discovered non-repeating FRB 181112 with four successive narrow pulses may have an underlying periodicity of ~0.8 ms, which could be best explained by a rapidly-rotating massive neutron star remnant formed right after the BNS merger.  Based on this interpretation, we discuss the future implications for the NS equation of state that can be obtained if such a periodicity is detected from FRBs simultaneously with gravitational waves.  Furthermore, we propose a new scenario that a young (<~10 yr), massive neutron star left after the BNS merger could be the source of repeating FRBs like FRB 121102.