quasi-periodic oscillations


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quasi-periodic oscillations

(QPOs) Short-lived, periodic flux changes, frequently observed in low-mass X-ray binaries. They were first detected in EXOSAT observations, with typical frequencies being 1–20 Hz, and coherence lasting for several tens of pulses; such pulses cause broad peaks in the X-ray power spectra of the sources. These QPOs are believed to arise in oscillations associated with the accretion of matter onto the compact star (white dwarf or neutron star) in these systems, and may prove to be a generic signature of such accretion. More recent observations, particularly with RXTE, have shown more rapid QPOs, at kHz frequencies, possibly associated with the neutron star spin frequency.
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In 2014, Dheeraj Pasham (NASA Goddard) and colleagues weighed a potential IMBH using quasi-periodic oscillations (QPOs), cyclic blips in a black hole's X-ray signal that astronomers suspect are related to the object's mass.
Twenty years after the discovery of neutron stars, quasi-periodic oscillations (QPOs) of X-rays were observed first from white dwarfs and then from neutron stars [13-14].
Intensity-dependent quasi-periodic oscillations in the X-ray flux of GX5-1.
This proposal aims to connect contemporary accretion and jet theory with observations of powerful outflows and quasi-periodic oscillations in accreting black hole systems.
From May 28 to June 2, the system's X-ray and radio emissions were fairly steady, although RXTE data show that cyclic X-ray variations, known as quasi-periodic oscillations or QPOs, gradually increased in frequency over the same period.
Interestingly, when eigen values occur in pairs (nearly equal values), they are indicative of quasi-periodic oscillations present in the original time series.
Astronomers call these rhythmic pulses quasi-periodic oscillations, or QPOs.
These signals, called quasi-periodic oscillations (QPOs), are semi-regular beats that sometimes appear in the X-ray emission from black holes and neutron stars when they're furiously accreting material.
From the figures we observe a quasi-periodic oscillations in the conductance (Fig.
Israel (Rome Astronomical Observatory, Italy) discovered quasi-periodic oscillations (QPOs) in the fading emission of the December 27, 2004, giant flare ("quasi-periodic" means that the vibrations have a narrow range of frequencies centered on one frequency).
A more abstruse mass estimate is possible for rapidly rotating X-ray pulsars, some of which display quasi-periodic oscillations with time scales of 3 milliseconds and less.

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