Thin disk models of anomalous X-ray pulsars

Abstract

We discuss the options of the fall-back disk model of Anomalous X-Ray Pulsars (AXPs). We argue that the power-law index of the mass inflow rate during the propeller stage can be lower than those employed in earlier models. We take into account the effect of the super-critical mass inflow at the earliest stages on the inner radius of the disk and argue that the system starts as a propeller. Our results show that, assuming a fraction of the mass inflow is accreted onto the neutron star, the fall-back disk scenario can produce AXPs for acceptable parameters.