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Session 23 - Degenerate Stars, Pulsars.
Display session, Tuesday, June 10
South Main Hall,
Since January 18, 1996, the Rossi X-ray Timing Explorer\/ (RXTE) has conducted regular observations of the transient X-ray pulsar and burst source GRO J1744-28. We discuss the properties of 91 out of 94 main bursts observed with RXTE\/ between January 18 and April 26, 1996, during the first outburst of this source. We use Fourier power spectra of the emission preceding and following bursts to quantify changes in the source variability related to the burst behavior; this analysis shows the presence of \sim 0.4 Hz QPO in the ``shoulders'' following some bursts. A quantitative analysis of the burst profiles demonstrates a strong correlation between the persistent emission level and the sizes of various burst features, and between the time scales of those features and that of the bursts themselves. An analysis of X-ray colors shows that the burst features are distinguishable by their X-ray spectra as well as by examination of the light curve. We suggest possible implications of these results for theories of the burst mechanism.
