On the infrared, optical, and high-energy emission from the anomalous X-ray pulsar 4U 0142+61

Abstract

We show that the observed pulsed optical emission of the anomalous X-ray pulsar 4 U 0142+61 can be accounted for by both the magnetar outer gap models and the disk-star dynamo gap models; therefore, there is no evidence favoring only one of these models as its responsible mechanism. Nevertheless, the estimated high-energy gamma-ray spectra from these models have different power-law indices and can be tested by future observations with the Gamma-Ray Large Area Space Telescope (GLAST). Furthermore, we show by analytical estimations that the expectations of a standard disk model are in agreement with the observed unpulsed optical and infrared luminosities of the AXP 4U 0142+61.