Observations of Accreting Pulsars Lars Deepto

We summarize 5 years of continuous monitoring of accretion-powered pulsars with the Burst and Transient Source Experiment (BATSE) on the Compton Gamma Ray Observatory. Our 20È70 keV observations have determined or reÐned the orbital parameters of 13 binaries, discovered Ðve new transient accreting pulsars, measured the pulsed Ñux history during outbursts of 12 transients (GRO J1744[28, 4U 0115]634, GRO J1750[27, GS 0834[430, 2S 1417[624, GRO J1948]32, EXO 2030]375, GRO J1008[57, A0535]26, GRO J2058]42, 4U 1145[619, and A1118[616), and also measured the accretion torque history during outbursts of six of those transients whose orbital parameters were also known. We have also continuously measured the pulsed Ñux and spin frequency for eight persistently accreting pulsars (Her X-1, Cen X-3, Vela X-1, OAO 1657[415, GX 301[2, 4U 1626[67, 4U 1538[52, and GX 1]4). Because of their continuity and uniformity over a long baseline, BATSE observations have provided new insights into the long-term behavior of accreting magnetic neutron stars. We have found that all accreting pulsars show stochastic variations in their spin frequencies and luminosities, including those displaying secular spin-up or spin-down on long timescales, which blurs the conventional distinction between disk-fed and wind-fed binaries. Pulsed Ñux and accretion torque are strongly correlated in outbursts of transient accreting pulsars but are uncorrelated, or even anticorrelated, in persistent sources. We describe daily folded pulse proÐles, frequency, and Ñux measurements that are available through the Compton Observatory Science Support Center at NASA/Goddard Space Flight Center. Subject headings : accretion, accretion disks È binaries : close È pulsars : general È stars : magnetic Ðelds È stars : neutron È X-rays : stars