RXTE Observation of the Low-Mass X-ray Binary Pulsar GX1+4

Abstract

We present the study of the aperiodic time variation of the low mass X‐ray pulsar GX 1+4 observed with the Rossi X‐Ray Timing Explorer (RXTE) satellite. At the bright state in 2002, we discovered, for the first time, the delayed iron line as compared to the continuum X‐rays in GX 1+4. Assuming that the iron emission lines are fluorescent lines in origin and are emitted by circumstellar matter, we derived 0.24±0.08 s for the time delay of the temporal variation of the iron line from the continuum X‐rays. This result leads to a determination of (7.2±2.4)×109 cm for the distance between the original X‐ray source and reprocessor of the iron lines. If the iron lines is the fluorescent iron line from the cold matter at the Alfven shell, we can derive the magnetic field strength of GX 1+4 to be an 2.5×1013 G.