Spiral-wave wind for the blue kilonova

In 1907.04872 we investigate the new mechanism of mass ejection from the BNS systems after merger. We find that the interaction between the remnant, should it survive, and the disk creates a characteristic spiral wave structure in the latter and drives the quasi-steady state outflow with total mass ~10^{-2} solar masses and fine-tuned velocity around 0.2c and high electron fraction of >0.25. This spiral-wave wind persists as long as remnant lives and dies out quickly after the BH formation. Its properties are robust with resolution and inclusion of the subgird turbulence. Then we use the data from numerical relativity simulations to compute the kilonova models. We report that the combination of dynamical ejecta and spiral-wave wind can account for early-time observed light curves.

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