AAS 203rd Meeting, January 2004
Session 53 Pulsars and Other Neutron Stars
Poster, Tuesday, January 6, 2004, 9:20am-6:30pm, Grand Hall

## [53.05] Torque and Lunimosity History of the Transient Pulsar SAX~J2103.5+4545

M. J. Stark, M. Saia (Lafayette College), J. H. Swank (LHEA / NASA's GSFC), A. Baykal (Middle East Technical University)

We have studied the transient outbursts of SAX~J2103.5+4545 with the {\em Rossi X-Ray Timing Explorer\/} The most recent outburst was followed by an extended period of persistent emission during which, while the source was very faint, it was still clearly detectable. Our earier studies of the transient outbursts of this source have established that the torque on the pulsar is related to the mass accretion rate in the expected way. The persistent emission we have observed varries in intensity and the observed torque varies in magnitude as well as sign. This observation has provided a wealth of data for us to explore in detail the relationship of the accretion torque to the mass accretion rate when the positive torque due to the angular momentum of infalling material is nearly balanced by the negative torque due to threading of the stellar magnetic field through the accretion disk beyond the corotation radius.