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HEXTE Studies of Sco X-1 Spectra: Detections of Hard X-Ray Tails Beyond 200 keV

F. D'Amico·W. A. Heindl·R. E. Rothschild·L. E. Peterson·D. E. Gruber·M. Pelling·J. A. Tomsick
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Abstract

Using the HEXTE experiment on-board the RXTE satellite, we performed a search for hard X-ray tails in Sco X-1 spectra. We found strong evidence for the presence of such a non-thermal component on several occasions. Using the PCA/RXTE we were able to track the position of the source along the Z diagram, and we observed that the presence of the hard X-ray tail is not confined to a particular region. However, we found a correlation between the power law index of the non-thermal component and the position of the source in the Z diagram, suggesting that the hard X-ray spectrum (i.e., E > 50 keV) becomes flatter as the mass accretion rate increases. We were also able to study the temporal variation of the appearance/absence of the hard X-ray component. With our derived luminosities, we were also able to test the idea that X-ray luminosities can be used to distinguish between X-ray binary systems containing neutron stars and black holes.

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F. D'Amico, W. A. Heindl, R. E. Rothschild, L. E. Peterson, D. E. Gruber, M. Pelling, J. A. Tomsick. 2001-01-22. HEXTE Studies of Sco X-1 Spectra: Detections of Hard X-Ray Tails Beyond 200 keV. https://doi.org/10.1016/s0273-1177(01)00436-7

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