Dependence of the Frequency of the Kilohertz Quasi-Periodic Oscillations on X-ray Count Rate and Colors in 4U 1608-52

Abstract

We present new results based on observations carried out with the Rossi X-ray Timing Explorer during the decay of an outburst of the low-mass X-ray binary (LMXB) and atoll source 4U 1608-52. Our results appear to resolve, at least in 4U 1608-52, one of the long-standing issues about the phenomenology of the kilohertz quasi-periodic oscillations (kHz QPOs), namely, the lack of a unique relation between the frequency of the kHz QPOs and the X-ray flux. We show that despite its complex dependence on the X-ray flux, the frequency of the kHz QPOs is monotonically related to the position of the source in the color-color diagram. Our findings strengthen the idea that, as in the case of Z sources, in the atoll sources the X-ray flux is not a good indicator of $\dot{M}$, and that the observed changes in the frequency of the kHz QPOs in LMXBs are driven by changes in $\dot{M}$. These results raise some concern about the recently reported detection of the orbital frequency at the innermost stable orbit in 4U 1820-30.

Accepted for publication in The Astrophysical Journal Letters. Uses AAS LaTex v4.0 (5 pages plus 4 postscript figures)

References in corpus (13)

• Kilohertz QPO Peak Separation Is Not Constant in Scorpius X-1
• Correlation Between Energy Spectral States and Fast Time Variability and Further Evidence for the Marginally Stable Orbit in 4U 1820-30
• Kilohertz Quasi-Periodic Oscillation Peak Separation is not Constant in the Atoll Source 4U 1608-52
• Milli-second Oscillations in the Persistent and Bursting Flux of Aql X-1 During an Outburst
• Discovery of a second kHz QPO peak in 4U 1608-52
• Strong Correlation Between Noise Features at Low Frequency and the Kilohertz QPOs in the X-Ray Binary 4U 1728-34
• KiloHertz Quasi-Periodic Oscillations in GX 17+2
• Discovery of Two Simultaneous Kilohertz Quasi-Periodic Oscillations in KS 1731-260
• Difference Frequency of Kilohertz QPOs Not Equal to Half the Burst Oscillation Frequency in 4U 1636-53
• Discovery of a Second Kilohertz QPO in the X-ray Binary 4U 1735-44
• Discovery of KiloHertz Quasi-Periodic Oscillations in 4U 1735-44
• Discovery of Kilohertz QPOs in the Atoll X-Ray Binary 4U 1705-44
• Kilohertz Quasi-Periodic Oscillations in Low-Mass X-Ray Binaries - a Review

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