Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Kilohertz quasi-periodic oscillations in neutron-star X-ray binaries:
  Flattening of the lag spectrum with increasing luminosity   We study the energy-dependent time lags and rms fractional amplitude of the
kilohertz quasi-periodic oscillations (kHz QPOs) of a group of neutron-star low
mass X-ray binaries (LMXBs). We find that for the lower kHz QPO the slope of
the best-fitting linear model to the time-lag spectrum and the total rms
amplitude integrated over the 2 to 25 keV energy band both decrease
exponentially with the luminosity of the source. For the upper kHz QPO the
slope of the time-lag spectrum is consistent with zero, while the total rms
amplitude decreases exponentially with the luminosity of the source. We show
that both the slope of the time-lag spectrum and the total rms amplitude of the
lower kHz QPO are linearly correlated with a slope of ~1. Finally, we discuss
the mechanism that could be responsible for the radiative properties of the kHz
QPOs, with the variability originating in a Comptonising cloud or corona that
is coupled to the innermost regions of the accretion disc, close to the neutron
star.

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The categories of this paper are: patt-sol
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The categories of this paper are: stat
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The categories of this paper are: q-alg
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The categories of this paper are: alg-geom
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The categories of this paper are: funct-an
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The categories of this paper are: hep-ph
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The categories of this paper are: math
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The categories of this paper are: plasm-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: atom-ph
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The categories of this paper are: cmp-lg
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The categories of this paper are: math-ph
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The categories of this paper are: econ
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The categories of this paper are: q-fin
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The categories of this paper are: eess
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The categories of this paper are: solv-int