The white dwarf binary merger model of GRB 170817A

TL;DR

This paper presents a comprehensive model explaining the multi-wavelength emissions of GRB 170817A as resulting from a white dwarf binary merger, resolving its mysterious origin and energetics.

Contribution

It introduces a novel white dwarf merger model that accounts for the prompt and afterglow emissions of GRB 170817A, linking the event to white dwarf binary coalescence.

Findings

Model fits spectra, flux, and variability across wavelengths.

Ejecta driven by a massive, magnetized white dwarf.

Explains the energetics and long-term emissions of GRB 170817A.

Abstract

Following the GRB 170817A prompt emission lasting a fraction of a second, $10^8$ s of data in the X-rays, optical, and radio wavelengths have been acquired. We here present a model that fits the spectra, flux, and time variability of all these emissions, based on the thermal and synchrotron cooling of the expanding matter ejected in a binary white dwarf merger. The $10^{-3} M_\odot$ of ejecta, expanding at velocities of $10^9$ cm s$^{-1}$, are powered by the newborn massive, fast rotating, magnetized white dwarf with a mass of $1.3 M_\odot$, a rotation period of $\gtrsim 12$ s, and a dipole magnetic field $\sim 10^{10}$ G, born in the merger of a $1.0+0.8 M_\odot$ white dwarf binary. Therefore, the long-lasting mystery of the GRB 170817A nature is solved by the merger of a white dwarf binary that also explains the prompt emission energetics.