2010/03/17 by Fengyun Rao, T. Belloni, Tomaso Belloni +6 · 33 citations
Earth and Planetary Sciences · Physics and Astronomy · #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Binary number #Computational physics #Fundamental frequency #Harmonic #High-pressure geophysics and materials #Low frequency #Oscillation (cell signaling) #Physics #Pulsars and Gravitational Waves Research #Quality (philosophy) #Quantum mechanics #Spectral density #Spectral line #Statistics #astro-ph.HE
paper · pdf · doi:10.1088/0004-637x/714/2/1065
published in The Astrophysical Journal 714(2), 1065-1071 (IOP Publishing) · 7 pages, 9 figures, accepted for publication in The Astrophysical Journal
arxiv created 2010/03/17 · openalex publication_date 2010/04/15 · arxiv updated 2015/05/18 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
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 J1550−564 during its 1998 outburst. The QPO frequency is observed to vary on timescales between ∼100 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. 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. In addition to the QPO and its harmonic peaks, a new 1.5ν component was detected in the power spectra. This component is broad, with a quality factor of ∼0.6. 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. 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. At low energies, the lowest-frequency component dominates, while at high energies the higher-frequency one has a higher fractional rms. An interplay between these two components was also observed as a function of their characteristic frequency. In this source, the transition between the low/hard state and the hard-intermediate state appears to be a smooth process.