相关论文: High-frequency QPOs as a problem in physics: non-l…

We analyzed all published frequencies, nu_1 and nu_2, of the twin kilohertz quasi-periodic oscillations (kHz QPOs) in bright neutron star low-mass X-ray binaries. The two frequencies are well correlated but, contrary to recent suggestions,…

After reviewing the general-relativistic ``gap'' model of accretion, I discuss its relation to the high frequency quasi-periodic oscillations observed in low-mass X-ray binaries. The ``300'' Hz frequency seen in some X-ray bursts may be a…

High frequency quasi-periodic oscillations (HFQPOs) have been detected in microquasars and neutron star systems. The resonance model suggested by Kluzniak & Abramowicz (2000) explains twin QPOs as two weakly coupled nonlinear resonant…

We suggest an explanation for the twin kilohertz quasi-periodic oscillations (kHz QPOs) in low-mass X-ray binaries (LMXBs) based on magnetohydrodynamics (MHD) oscillation modes in neutron star magnetospheres. Including the effect of the…

We explore some properties of twin kilohertz quasiperiodic oscillations (QPOs) in a simple toy-model consisting of two oscillation modes coupled by a general nonlinear force. We examine resonant effects by slowly varying the values of the…

Strong, coherent, quasi-periodic brightness oscillations (QPOs) with frequencies ranging from about 300 Hz to 1200 Hz have been discovered with the Rossi X-ray Timing Explorer in the X-ray emission from some fifteen neutron stars in…

We report the discovery of quasi-periodic oscillations (QPOs) in the High Mass X-ray Binary (HMXB) pulsar LMC X-4 in its non-flaring (persistent) state using observations with XMM-Newton. In addition to the 74 mHz coherent pulsations, the…

Millihertz quasi-periodic oscillations (mHz QPOs) observed in neutron-star low-mass X-ray binaries (NS LMXBs) are generally explained as marginally stable thermonuclear burning on the neutron star surface. We report the discovery of mHz…

We discuss the possibility that high-frequency QPOs in neutron-star binary systems may result from forced resonant oscillations of matter in the innermost parts of the accretion disc, excited by gravitational perturbations coming from…

Some of the more promising ideas about the origin of the high frequency variability (kHz QPOs) in the observed X-ray emissions of low-mass X-ray binaries are contrasted with less promising ones.

Quasi-periodic oscillations (QPOs) at frequencies near 1000 Hz were recently discovered in several x-ray binaries containing neutron stars. Two sources show no correlation between QPO frequency and source count rate (Berger et al. 1996,…

The remarkable discovery of kilohertz quasi-periodic brightness oscillations (QPOs) in the accretion-powered emission from some sixteen neutron-star low-mass X-ray binary systems has led to much speculation about and theoretical modeling of…

It has been suggested that both X-ray bursters and millisecond radio pulsars may be strange (quark) stars, rather than neutron stars. Confirming (or rejecting) this suggestion may require knowing what role strong-field effects of general…

We study systematically the ~0.1-1200 Hz quasi-periodic oscillations (QPOs) and broad noise components observed in the power spectra of non-pulsing neutron-star and black-hole low-mass X-ray binaries. We show that among these components we…

Kilohertz quasi-periodic oscillations (kHz QPOs) are probably caused by matter in Keplerian orbit at some preferred radius in the accretion disc around a compact star. In a given source, QPO frequencies can drift by a few hundred Hz…

During observations with RXTE we discovered two simultaneous kHz QPOs near 500 Hz and 860 Hz in the Z source Cyg X-2. In the X-ray color-color diagram and hardness-intensity diagram (HID) a clear Z track was traced out. A single kHz QPO…

We explain the peak spacing in the power spectra of millisecond variability detected by the Rossi X-ray Timing Explorer (RXTE) in the X-ray emission from the LMXBs (Sco X-1, 4U1728-34, 4U1608-522, 4U1636-536, etc) in terms of the rotational…

The frequencies of the highest-frequency kilohertz QPOs recently discovered in some sixteen neutron stars in low-mass X-ray binary systems are most likely the orbital frequencies of gas in Keplerian orbit around these neutron stars. If so,…

Millisecond variability detected in low-mass X-ray binaries (LMXBs) probably reflects motions of accreting fluid in the strong-field gravity of neutron stars or neutron stars. Parametric resonance between two oscillators with unequal…

Observations with RXTE have revealed kilohertz quasi-periodic brightness oscillations (QPOs) from nearly twenty different neutron-star low-mass X-ray binaries (LMXBs). These frequencies often appear as a pair of kilohertz QPOs in a given…