Long Term Cooling of Magnetar Crusts
  X-ray emission following giant flares of magnetars can be categorized into three categories of time scales (a) short term afterglow (b) medium term afterglow and (c) long term afterglow. Short term afterglow, which declines over several hours, seems to correspond to gravitational resettling of uplifted material. Medium term afterglow, which declines over several weeks or months, appears to be the cooling of the heated outer crust, and long term afterglow, which declines over a period of many years, can be understood to be the cooling of the inner crust. The long term afterglow profile may be a very sensitive indicator of neutron star mass. 
David Eichler, Yuri Lyubarsky, Chryssa Kouveliotou, Colleen A. Wilson