Magnetars in the afterglow era

Abstract

The X-ray afterglow that is observed following large flares on magnetars can be accurately fit by simple and quantitative theoretical models: The long term afterglow, lasting of order weeks, can be understood as thermal radiation of a heated neutron star crust that is re-scattered in the magnetosphere. Short term afterglow is well fit by the cooling of a non-degenerate, pair-rich layer, which gradually shrinks and releases heat to a pair-free zone above it. Measurements of persistent optical and infrared emission directly probe long lived currents in the magnetosphere which are a likely source of collective plasma emission. The superstrong magnetic field plays an important role in generating these various emissions, and previous inference of its strength in magnetars is supported by the good fits with observation.