GRB 170817A-GW170817-AT 2017gfo and the observations of NS-NS, NS-WD and WD-WD mergers

TL;DR

This paper examines various binary merger scenarios to understand the origin of GW170817 and its electromagnetic counterpart, proposing a new model for WD-WD mergers as the source of GRB 170817A and AT 2017gfo.

Contribution

The study introduces a novel model attributing GRB 170817A and AT 2017gfo to WD-WD mergers, challenging previous associations with NS-NS mergers.

Findings

Current NS-NS and NS-WD merger models do not support the observed association.

A new WD-WD merger model aligns with multi-wavelength observations of GRB 170817A-AT 2017gfo.

Proposes WD-WD mergers as a plausible origin for certain short GRBs and kilonova-like emissions.

Abstract

The LIGO-Virgo Collaboration has announced the detection of GW170817 and has associated it with GRB 170817A. These signals have been followed after 11 hours by the optical and infrared emission of AT 2017gfo. The origin of this complex phenomenon has been attributed to a neutron star-neutron star (NS-NS) merger. In order to probe this association we confront our current understanding of the gravitational waves and associated electromagnetic radiation with four observed GRBs originating in binaries composed of different combinations NSs and white dwarfs (WDs). We consider 1) GRB 090510 the prototype of NS-NS merger leading to a black hole (BH); 2) GRB 130603B the prototype of a NS-NS merger leading to massive NS (MNS) with an associated kilonova; 3) GRB 060614 the prototype of a NS-WD merger leading to a MNS with an associated kilonova candidate; 4) GRB 170817A the prototype of a WD-WD merger leading to massive WD with an associated AT 2017gfo-like emission. None of these systems support the above mentioned association. The clear association between GRB 170817A and AT 2017gfo has led to introduce a new model based on on a new subfamily of GRBs originating from WD-WD mergers. We show how this novel model is in agreement with the exceptional observations in the optical, infrared, X- and gamma-rays of GRB 170817A-AT 2017gfo.