2000/08/17 by F. D'Amico, F. D’Amico, W. A. Heindl +6 · 1 citation
Physics and Astronomy · #Astrophysical Phenomena and Observations #Gamma-ray bursts and supernovae #Particle Detector Development and Performance #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/0008279
15 pages, 1 ps figure ; uses aastex.cls ; accepted for publication in ApJL
arxiv created 2000/11/16 · arxiv updated 2009/12/01
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.