paper

Subsequent Nonthermal Emission due to the Kilonova Ejecta in GW 170817

arXiv:1711.00699 · doi:10.3847/1538-4357/aaa3f5

Abstract

The ejected material at the binary neutron star merger GW 170817 was confirmed as a kilonova by UV, optical, and IR observations. This event provides a unique opportunity to investigate the particle acceleration at a mildly relativistic shock propagating in the circumbinary medium. In this paper, we simulate the nonthermal emission from electrons accelerated by the shock induced by the kilonova ejecta with a time-dependent method. The initial velocity and mass of the ejecta in the simulations are obtained from the kilonova observations in GW 170817. If the ambient density is high enough ($\geq 10^{-2}~\mbox{cm}^{-3}$), radio, optical/IR, and X-ray signals will be detected in a few years, though the off-axis short gamma-ray burst models, accounting for the X-ray/radio counterpart detected at days after the merger, implies low ambient density. We also demonstrate that the additional low-mass () component with a velocity of -- can reproduce the early X-ray/radio counterpart. This alternative model allows a favorably high density to detect the nonthermal emission due to the kilonova ejecta. Even for a low ambient density such as $\sim 10^{-3}~\mbox{cm}^{-3}$, depending on the microscopic parameters for the electron acceleration, we can expect a growth of radio flux of mJy in a few years.

arXiv comment5 pages, 5 figures, ApJ in press

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