Could FRB 131104 Originate from the Merger of Binary Neutron Stars?

TL;DR

This paper investigates whether the FRB 131104 and associated gamma-ray transient could originate from a binary neutron star merger, analyzing observational data and physical models to support this hypothesis.

Contribution

It provides new constraints on the environment and postmerger object, supporting a neutron star merger origin over other models, and predicts gravitational wave signals for future detection.

Findings

The environment density is consistent with galaxy outskirts, not interstellar medium.

The postmerger object is an ultra-strongly magnetized, rapidly rotating pulsar.

The merger could produce gravitational waves, an FRB, and gamma-ray emission, testable by LIGO and Virgo.

Abstract

Recently, DeLaunay et al. (2016) discovered a gamma-ray transient, Swift J0644.5-5111, associated with the fast radio burst (FRB) 131104. They also reported follow-up broadband observations beginning two days after the FRB and provided upper limits on a putative afterglow of this transient. In this paper, we show that if such a transient drives a relativistic shock as in a cosmological gamma-ray burst (GRB), these upper limits are consistent with an environment of which density is much less than that of an interstellar medium but typical for the outskirts' density of a galaxy when the typical values of three microphysical parameters of the shock are taken. This appears to be inconsistent with the catastrophic event models in which the central engine of Swift J0644.5-5111 is surrounded by an interstellar medium, but together with the properties of the gamma-ray transient, favors the binary neutron star merger origin. We further constrain the physical parameters of the postmerger object by assuming that Swift J0644.5-5111 results from internal dissipation of a spinning-down pulsar wind, and we find that the postmerger object is an ultra-strongly magnetized, very rapidly rotating pulsar. This merger event should have given birth to a gravitational wave burst, an FRB, and a short GRB or an extended X-ray/gamma-ray emission if a relativistic jet of the GRB is missed. Such "triplets" would be testable in the near future with the advanced LIGO and Virgo gravitational-wave observatories.