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HEXTE Detections of Hard X-Ray Tails in Sco X-1

F. D'Amico·W. A. Heindl·R. E. Rothschild·D. E. Gruber
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Abstract

We report the detection of a non-thermal hard X-ray component from Sco X-1 based upon the analysis of 20-220 keV spectra obtained with the HEXTE experiment on-board the RXTE satellite. We find that the addition of a power-law component to a thermal bremsstrahlung model is required to achieve a good fit in 5 of 16 observations analyzed. Using PCA data we were able to track the movement of the source along the Z diagram, and we found that the presence of the hard X-ray tail is not confined to a specific Z position. However, we do observe an indication that the power law index hardens with increasing mass accretion rate, as indicated from the position on the Z diagram. We find that the derived non-thermal luminosities are at order of 10% of that derived for the brightest of the atoll sources.

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F. D'Amico, W. A. Heindl, R. E. Rothschild, D. E. Gruber. 2000-11-16. HEXTE Detections of Hard X-Ray Tails in Sco X-1. https://arxiv.org/abs/astro-ph/0008279

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