First observation of a transition between “ parallel tracks ” in the kHz QPO frequency vs . intensity diagram
نویسنده
چکیده
Abstract. Contrary to theoretical expectations, observations with the Rossi X-ray Timing Explorer (RXTE) show that in X-ray binaries timing properties are not uniquely correlated with X-ray luminosity. For instance, although the frequencies of the kilohertz quasi-periodic oscillations (kHz QPOs) correlate with X-ray flux on short (∼few hours) time scales, on time scales longer than a day the QPO appears at more or less the same frequency, whereas the luminosity may be a factor of a few different. The result is a set of almost parallel tracks in a QPO frequency vs. X-ray flux plot. Despite the “parallel tracks” are a common phenomenon among kHz QPO sources, until now, after five years of observations with RXTE, not a single transition between two of these tracks had been seen. Here I present the first detection of such a transition, in 4U 1636–53.
منابع مشابه
The Amplitude of the Kilohertz Quasi-periodic Oscillations in 4u 1728–34, 4u 1608–52, and Aql X-1, as a Function of X-ray Intensity
We study the kilohertz quasi-periodic oscillations (kHz QPOs) in the low-mass X-ray binaries 4U 1728–34, 4U 1608–52, and Aql X-1. Each source traces out a set of nearly parallel tracks in a frequency vs. X-ray count rate diagram. We find that between two of these tracks, for similar QPO frequency, the 2 − 60 keV source count rate can differ by up to a factor of ∼ 4, whereas at the same time the...
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We have produced the colour-colour diagram of all the observations of 4U 1728–34 available in the Rossi X-ray Timing Explorer public archive (from 1996 to 2002) and found observations filling in a previously reported ‘gap’ between the island and the banana X-ray states. We have made timing analysis of these gap observations and found, in one observation, two simultaneous kHz quasi-periodic osci...
متن کاملEvidence of a decrease of kHz quasi - periodic oscillation peak separation towards low frequencies in 4 U 1728 – 34 ( GX 354 – 0 )
We have produced the colour–colour diagram of all the observations of 4U 1728–34 available in the Rossi X-ray Timing Explorer public archive (from 1996 to 2002) and found observations filling in a previously reported ‘gap’ between the island and the banana X-ray states. We have made timing analysis of these gap observations and found, in one observation, two simultaneous kHz quasi-periodic osci...
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