AAS 205th Meeting, 9-13 January 2005
Session 83 Neutron Stars and Pulsars
Oral, Tuesday, January 11, 2005, 2:00-3:30pm, California

[83.03] Pulsar frequency glitches in the Accreting pulsar SAX J2103.5+4545

M. J. Stark, C. M. Heffner (Lafayette College), A. Baykal (Middle East Technical University), J. H. Swank (NASA/Goddard Space Flight Center)

We have had a program of continuous observation of SAX~J2103.5+4545 with the {\em Rossi X-Ray Timing Explorer\/} for more than two years. We have been able to unambiguously count the revolutions of the pulsar over this entire period. The period is characterized by weak spin-up of the pulsar which is dependent on the varying rate of accretion. During this period we observed two incidents where there was a sudden increase in the pulsar frequency. During these incidents, the fractional change in the frequency was 8\times10-5 and 3\times10-4. These {\em glitches\/} are larger than radio pulsar glitches and different from them in several important respects. However, they are substantially similar to an event recently reported in data from KS~1947+300. It is difficult to understand these events in terms of accretion-induced changes in the rotation so they may yet bear some relation to radio pulsar glitches. These observations suggest the need for better monitoring of accreting X-ray pulsars. This work is supported in part by a grant from NASA.