The AT2017gfo kilonova counterpart of the binary neutron star merger event GW170817 was characterized by an early-time bright peak in optical and UV bands. Such blue kilonova is commonly interpreted as a signature of weak r-process nucleosynthesis in a fast expanding wind whose origin is currently debated. Numerical-relativity simulations with microphysical equations of state, approximate neutrino transport, and turbulent viscosity reveal a new mechanism that can power the blue kilonova. Spiral density waves in the remnant generate a characteristic wind of mass ∼10−2M⊙ and velocity ∼0.2c. The ejected material has electron fraction mostly distributed above 0.25 being partially reprocessed by hydrodynamic shocks in the expanding arms. The combination of dynamical ejecta and spiral-wave wind can account for solar system abundances of r-process elements and early-time observed light curves.
@article{arxiv.1907.04872,
title = {Spiral-wave wind for the blue kilonova},
author = {Vsevolod Nedora and Sebastiano Bernuzzi and David Radice and Albino Perego and Andrea Endrizzi and Néstor Ortiz},
journal= {arXiv preprint arXiv:1907.04872},
year = {2019}
}