![]() We observe a low-frequency quasi-periodic oscillation (LFQPO) with a centroid frequency that tends to increase with increasing flux and a fractional rms amplitude which is correlated with the hardness ratio. We report on timing and spectral observations of the 2000 outburst of XTE J 1550-564 made by the Unconventional Stellar Aspect (USA) Experiment on board the Advanced Research and Global Observation Satellite (ARGOS). USA Observation of Spectral and Timing Evolution During the 2000 Outburst of XTE J 1550-564Įnergy Technology Data Exchange (ETDEWEB) In this source, the transition between the low/hard state and the hard-intermediate state appears to be a smooth process. An interplay between these two components was also observed as a function of their characteristic frequency. ![]() At low energies, the lowest-frequency component dominates, while at high energies the higher-frequency one has a higher fractional rms. We also studied the energy dependence of the timing features and conclude that the two continuum components observed in the power spectrum, although both more intense at high energies, show a different dependence on energy. From this, we argue that the peak observed at half the QPO frequency, usually referred to as 'sub-harmonic', could be the fundamental frequency, leading to the sequence 1:2:3:4. This component is broad, with a quality factor of âˆ❀.6. In addition to the QPO and its harmonic peaks, a new 1.5ν component was detected in the power spectra. In all observations, the quality factors (ν 0 /FWHM) of the fundamental and second harmonic peaks were observed to be consistent, suggesting that the quasi-periodic nature of the oscillation is due to frequency modulation. The QPO frequency is observed to vary on timescales between âˆ❁00 s and days, correlated with the count rate contribution from the optically thick accretion disk: we studied this correlation and discuss its influence on the QPO width. We present the results of a timing analysis of the low-frequency quasi-periodic oscillation (QPO) in the Rossi X-Ray Timing Explorer data of the black hole binary XTE J 1550-564 during its 1998 outburst. Rao Fengyun Belloni, Tomaso Stella, Luigi Zhang Shuangnan Li Tipei International Nuclear Information System (INIS) LOW-FREQUENCY OSCILLATIONS IN XTE J 1550-564 Radio flux density upper limits (3σ) of 26 μJy (at 5.5 GHz), 47 μJy (at 9 GHz) for GRO J1655−40 and We present the results of radio observations of the black hole binaries GRO J1655−40 and XTE J 1550− 564 in quiescence, with the upgraded Australia Telescope Compact Array. ![]() Limits on the quiescent radio emission from the black hole binaries GRO J1655−40 and XTE J 1550− 564Ĭalvelo, D.E. ![]()
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