scholarly journals Quasi-Periodic Oscillations in Low-Mass X-ray Binaries

1987 ◽  
Vol 125 ◽  
pp. 321-331
Author(s):  
M. van der Klis
Keyword(s):  
Neutron Star ◽  
Low Frequency ◽  
Frequency Noise ◽  
Low Frequency Noise ◽  
Periodic Oscillations ◽  
X Ray ◽  
Low Mass ◽  
X Ray Binaries

The properties of the rapid, persistent quasi-periodic oscillations (QPO) discovered with EXOSAT in the X-ray flux of at least 7 bright low-mass X-ray binaries are described. Particular attention is given to the various relations observed between QPO frequency and X-ray intensity, the link between QPO and the low-frequency noise in the X-ray intensity and the bimodal properties of in particular Sco X-1, GX 5-1 and Cyg X-2. The merits of the hypothesis that the QPO indicate the presence of a neutron star with a magnetosphere are considered.

scholarly journals The Beat-Frequency Interpretation of Kilohertz Quasi-periodic Oscillations in Neutron Star Low-Mass X-Ray Binaries

1998 ◽  
Vol 501 (1) ◽  
pp. L95-L99 ◽  
Author(s):  
Dimitrios Psaltis ◽  
Mariano Méndez ◽  
Rudy Wijnands ◽  
Jeroen Homan ◽  
Peter G. Jonker ◽  
...  
Keyword(s):  
Neutron Star ◽  
Beat Frequency ◽  
Periodic Oscillations ◽  
X Ray ◽  
Frequency Interpretation ◽  
Low Mass ◽  
X Ray Binaries

scholarly journals Neutron star QPOs from oscillating, precessing hot, thick flow

2019 ◽  
Vol 491 (3) ◽  
pp. 3245-3250
Author(s):  
P Chris Fragile
Keyword(s):  
Neutron Star ◽  
Low Frequency ◽  
Outer Radius ◽  
Horizontal Branch ◽  
X Ray ◽  
Best Fitting ◽  
Low Mass ◽  
The Moment ◽  
X Ray Binaries ◽  
Simultaneous Oscillation

ABSTRACT Across black hole (BH) and neutron star (NS) low-mass X-ray binaries (LMXBs), there appears to be some correlation between certain high- and low-frequency quasi-periodic oscillations (QPOs). In a previous paper, we showed that for BH LMXBs, this could be explained by the simultaneous oscillation and precession of a hot, thick, torus-like corona. In the current work, we extend this idea to NS LMXBs by associating the horizontal branch oscillations (HBOs) with precession and the upper-kiloHertz (ukHz) QPO with vertical epicyclic motion. For the Atoll source 4U 1608-52, the model can match many distinct, simultaneous observations of the HBO and ukHz QPO by varying the inner and outer radius of the torus, while maintaining fixed values for the mass (MNS) and spin (a*) of the NS. The best-fitting values are MNS = 1.38 ± 0.03 M⊙ and a* = 0.325 ± 0.005. By combining these constraints with the measured spin frequency, we are able to obtain an estimate for the moment of inertia of INS = 1.40 ± 0.02 × 1045 g cm2, which places constraints on the equation of state. The model is unable to fit the lower-kHz QPO, but evidence suggests that QPO may be associated with the boundary layer between the accretion flow and the NS surface, which is not treated in this work.

scholarly journals Statistical properties of twin kilohertz quasi-periodic oscillations in neutron star low-mass X-ray binaries

2014 ◽  
Vol 335 (2) ◽  
pp. 168-177 ◽  
Author(s):  
D. H. Wang ◽  
L. Chen ◽  
C. M. Zhang ◽  
Y. J. Lei ◽  
J. L. Qu
Keyword(s):  
Neutron Star ◽  
Statistical Properties ◽  
Periodic Oscillations ◽  
X Ray ◽  
Low Mass ◽  
X Ray Binaries

scholarly journals Detection of millihertz quasi-periodic oscillations in the X-Ray binary 1RXS J180408.9−342058

2020 ◽  
Vol 500 (1) ◽  
pp. 34-39
Author(s):  
Kaho Tse ◽  
Duncan K Galloway ◽  
Yi Chou ◽  
Alexander Heger ◽  
Hung-En Hsieh
Keyword(s):  
Neutron Star ◽  
Power Law ◽  
Numerical Models ◽  
Periodic Oscillations ◽  
X Ray ◽  
Thermonuclear Burning ◽  
Low Mass ◽  
Power Law Noise ◽  
Star Surface ◽  
X Ray Binaries

ABSTRACT 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 QPOs in an XMM–Newton observation of the transient 1RXS J180408.9−342058, during a regular bursting phase of its 2015 outburst. We found significant periodic signals in the March observation, with frequencies in the range 5–8 $\, \mathrm{mHz}$, superimposed on a strong ∼1/f power-law noise continuum. Neither the QPO signals nor the power-law noise were present during the April observation, which exhibited a 2.5 × higher luminosity and had correspondingly more frequent bursts. When present, the QPO signal power decreases during bursts and disappears afterwards, similar to the behaviour in other sources. 1RXS J180408.9−342058 is the eighth source known to date that exhibits such QPOs driven by thermonuclear burning. We examine the range of properties of the QPO signals in different sources. Whereas the observed oscillation profile is similar to that predicted by numerical models, the amplitudes are significantly higher, challenging their explanation as originating from marginally stable burning.

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