Plastic damping of Alfv\'en waves in magnetar flares and delayed afterglow emission
Abstract
Magnetar flares generate Alfv\'en waves bouncing in the closed magnetosphere with energy up to 1046 erg. We show that on a 10-ms timescale the waves are transmitted into the star and form a compressed packet of high energy density. This packet strongly shears the stellar crust and initiates a plastic flow, heating the crust and melting it hundreds of meters below the surface. A fraction of the deposited plastic heat is eventually conducted to the stellar surface, contributing to the surface afterglow months to years after the flare. A large fraction of heat is lost to neutrino emission or conducted into the core of the neutron star.
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