Compact binary merger and kilonova: outflows from remnant disc

TL;DR

This study uses numerical simulations to analyze outflows from remnant discs of compact binary mergers, showing they can produce kilonova emissions consistent with observations like GW170817.

Contribution

It introduces a model incorporating limited-energy advection in hyper-accretion discs to explain outflow properties and their role in kilonova emissions.

Findings

Outflows can eject 10^{-3} to 10^{-1} solar masses of material.

Outflow luminosity ranges from 10^{40} to 10^{41} erg/s.

Results align with observed kilonovae like AT2017gfo.

Abstract

Outflows launched from a remnant disc of compact binary merger may have essential contribution to the kilonova emission. Numerical calculations are conducted in this work to study the structure of accretion flows and outflows. By the incorporation of limited-energy advection in the hyper-accretion discs, outflows occur naturally from accretion flows due to imbalance between the viscous heating and the sum of the advective and radiative cooling. Following this spirit, we revisit the properties of the merger outflow ejecta. Our results show that around $10^{-3} \sim 10^{-1} M_\odot$ of the disc mass can be launched as powerful outflows. The amount of unbound mass varies with the disc mass and the viscosity. The outflow-contributed peak luminosity is around $10^{40} \sim 10^{41}$ erg/s. Such a scenario can account for the observed kilonovae associated with short gamma-ray bursts, including the recent event AT2017gfo (GW170817).