author = "D'Amico, Fl{\'a}vio and Heindl, W. A. and Rothschild, R. E. and 
                         Gruber, D. E",
          affiliation = "Univ Calif San Diego, Ctr Astrophys \& Space Sci, La Jolla, USA 
                         and Inst Nacl Pesquisas Espaciais, Divis{\~a}o de 
                title = "High-Energy X-Ray Timing Experiment detections of hard X-ray tails 
                         in Scorpius X-1",
              journal = "Astrophysical Journal",
                 year = "2001",
               volume = "547",
               number = "2 Part 2",
                pages = "L147--L150",
                month = "Feb.",
             keywords = "Astrof{\'{\i}}sica, binaries : general, stars : individual 
                         (Scorpius X 1), stars : neutron, X-rays : stars, performance, 
                         explorer, spectrum.",
             abstract = "We report the detection of a nonthermal hard X-ray component from 
                         Sco X-1 based on the analysis of 20-220 keV spectra obtained with 
                         the High-Energy X-Ray Timing Experiment on board the Rossi X-Ray 
                         Timing Explorer satellite. We find that the addition of a 
                         power-law component to a thermal bremsstrahlung model is required 
                         to achieve a good fit in five of 16 observations analyzed. Using 
                         Proportional Counter Array 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 M, as indicated from the position on 
                         the Z diagram. We find that the derived nonthermal luminosities 
                         are similar to 10% of that derived for the brightest of the atoll 
           copyholder = "SID/SCD",
                 issn = "0004-637X and 1538-4357",
             language = "en",
           targetfile = "High-energy x-ray timing experiment detections of hard x-ray tails 
                         in scorpius x-1.pdf",
        urlaccessdate = "16 jan. 2021"