Fossil Disks and Propellor Spindown of SGR/AXPs

Abstract

We have shown that the interstellar media which surround the progenitors of SGRs and AXPs were unusually dense compared to the environments around most young radio pulsars. This environmental correlation argues strongly against the current magnetar model for SGRs and AXPs. We suggest instead that they are neutron stars with sub-critical magnetic fields and are spun down rapidly by ``propeller'' torques from fossil disks formed from the fallback of supernova ejecta. We show that this hypothesis is consistent with the observed properties of these enigmatic objects, and we compare the propeller and magnetar models for SGR and AXPs.