摘要 :
In the context of black hole spin in X_ray binaries, we propose that certain types of quasi-periodic oscillations (QPOs) observed in the light curves of black hole binaries(BHBs) are produced by X-ray modulation at the precession ...
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In the context of black hole spin in X_ray binaries, we propose that certain types of quasi-periodic oscillations (QPOs) observed in the light curves of black hole binaries(BHBs) are produced by X-ray modulation at the precession frequency of accretion disks, because of relativistic dragging of inertial frames around spinning black holes. These QPOs tend to be relatively stable in their centroid frequencies. They have been observed in the frequency range of a few hertz to a few hundred hertz for several black holes with dynamically determined masses.
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摘要 :
We report the discovery of strong aperiodic X-ray vanability and quasi-periodic oscillation (QPO) in the X- ray light curves of a new X-ray nova, XTE J1550-564, and the evolution of the observed temporal properties during the rise...
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We report the discovery of strong aperiodic X-ray vanability and quasi-periodic oscillation (QPO) in the X- ray light curves of a new X-ray nova, XTE J1550-564, and the evolution of the observed temporal properties during the rise of the recent X-ray outburst. The power spectral analysis of the first observation reveals strong aperiodic X-ray variability of the source (~28) as well as the presence of a QPO at ~82 mHz with fractional rms amplitude ~14 over the 2-60 keV energy range. Also apparent is the first harmonic of the QPO with the amplitude ~9. As the X-ray flux increases, the source tends to become less variable, and the QPO frequency increases rapidly, from 82 mHz to 4 Hz, over the flux (2-50 keV) range Of 1.73-5.75 x 10~(-8) ergs cm~(-2) s~(-1), The amplitude of the fundamental component of the QPO varies little while that of the harmonic follows a decreasing trend. The fundamental component strengthens toward high energies, while its harmonic weakens. Initially, the power spectrum is roughly flat at low frequencies and turns into a power law at high frequencies, with the QPO harmonic sitting roughly at the break. In later observations, however, the high-frequency portion of the continuum can actually be better described by a broken power law (as opposed to a simple power law). This effect becomes more apparent at higher energies. The overall amplitude of the continuum shows a similar energy dependence to that of the fundamental component of the QPO. Strong rapid X-ray variability, as well as a hard energy spectrum, makes XTE J1550-564 a good black hole candidat
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摘要 :
We discuss the observational consequences of black hole spin in X-ray binaries within the framework of the standard thin accretion disk model. When compared with theoretical flux distri- bution from the surface of a thin disk surr...
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We discuss the observational consequences of black hole spin in X-ray binaries within the framework of the standard thin accretion disk model. When compared with theoretical flux distri- bution from the surface of a thin disk surrounding a Kerr black hole, the observed X-ray properties of the Galactic superluminal jet sources, GRO J1655-40 and GRS 1915+105, strongly suggest that each contains a black hole spinning rapidly in the same direction as the accretion disk. We show, however, that some other black hole binaries with an ultrasoft X-ray component probably harbor only non- or slowly spinning black holes, and we argue that those with no detectable ultrasoft component above 12 keV in their high luminosity state may contain a fast-spinning black hole but with a retrograde disk. Therefore, all classes of known black hole binaries are united within one scheme. Furthermore, we explore the possibility that spectral state transitions in Cyg X-1 are simply due to temporary disk reversal, which can occur in a wind accretion system.
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