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The 3-53 keV Spectrum of the Quasar 1508+5714: X-rays from z = 4.3

Edward C. Moran·David J. Helfand
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Abstract

We present a high-quality X-ray spectrum in the 3--53 keV rest-frame band of the radio-loud quasar 1508+5714, by far the brightest known X-ray source at z > 4. A simple power-law model with an absorption column density equal to the Galactic value in the direction of the source provides an excellent and fully adequate fit to the data; the measured power-law photon index Gamma = 1.42 (+0.13,-0.10). Upper limits to Fe K alpha line emission and Compton-reflection components are derived. We offer evidence for both X-ray and radio variability in this object and provide the first contemporaneous radio spectrum (alpha = -0.25). The data are all consistent with a picture in which the emission from this source is dominated by a relativistically beamed component in both the X-ray and radio bands.

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Edward C. Moran, David J. Helfand. 1997-05-19. The 3-53 keV Spectrum of the Quasar 1508+5714: X-rays from z = 4.3. https://doi.org/10.1086/310787

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