An OSSE Observation of Soft Gamma-Ray Emission from A0535+26

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Session 9 -- Galactic X-Ray/Gamma-Ray Sources
Display presentation, Monday, 30, 1994, 9:20-6:30

[9.08] An OSSE Observation of Soft Gamma-Ray Emission from A0535+26

J.E.~Grove, M.S.~Strickman (NRL), C. Starr (USRA), E.~Kendziorra, M.~Maisack, R.~Staubert (AIT)

The Oriented Scintillation Spectrometer Experiment (OSSE) on GRO observed the X-ray binary pulsar A0535+26 from 8-17~February~1994, during the rising portion of an unusually strong outburst. We find that the phase-averaged spectrum shows interesting structure above 100~keV and cannot be described by a single-component model. Lightcurves near 50~keV show a double-peaked pulse profile, and pulse-phase spectroscopy indicates significant spectral dependence on phase. We will present both phase-averaged and phase-resolved spectroscopy, plus time histories of the observed flux. We will show whether spectra can be interpreted in terms of a cyclotron absorption feature and/or the emergence of an underlying hard component. We will also discuss evolution of the spectral shape over the course of the observation.

Monday program listing