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ASCA Observations of OAO 1657-415 and its Dust-Scattered X-Ray Halo

Michael D. Audley·Fumiaki Nagase·Kazuhisa Mitsuda·Lorella Angelini·Richard L. Kelley
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Abstract

We report on two ASCA observations of the high-mass X-ray binary pulsar OAO 1657-415. A short observation near mid-eclipse caught the source in a low-intensity state, with a weak continuum and iron emission dominated by the 6.4-keV fluorescent line. A later, longer observation found the source in a high-intensity state and covered the uneclipsed through mid-eclipse phases. In the high-intensity state, the non-eclipse spectrum has an absorbed continuum component due to scattering by material near the pulsar and 80 per cent of the fluorescent iron emission comes from less than 19 lt-sec away from the pulsar. We find a dust-scattered X-ray halo whose intensity decays through the eclipse. We use this halo to estimate the distance to the source as 7.1 +/- 1.3 kpc.

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Michael D. Audley, Fumiaki Nagase, Kazuhisa Mitsuda, Lorella Angelini, Richard L. Kelley. 2006-01-04. ASCA Observations of OAO 1657-415 and its Dust-Scattered X-Ray Halo. https://doi.org/10.1111/j.1365-2966.2006.10003.x

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