Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A Further Study of the Luminosity-Dependent Cyclotron Resonance Energies
  of the Binary X-ray Pulsar 4U0115+63 with RXTE   The present paper reports on the RXTE observations of the binary X-ray pulsar
4U0115+63, covering an outburst in 1999 March-April with 44 pointings. The 3-30
keV PCA spectra and the 15-50 keV HEXTE spectra were analyzed jointly for the
cyclotron resonance features. When the 3-50 keV luminosity at an assumed
distance of 7 kpc was in the range (5-13)x10^{37} erg s^{-1}, harmonic double
cyclotron features were observed in absorption at ~11 and ~22 keV, as was
measured previously during typical outbursts. As the luminosity decreased below
\~5x10^{37} erg s^{-1}, the second resonance disappeared, and the fundamental
resonance energy gradually increased, up to $\sim$16 keV at 0.16x10^{37} erg
s^{-1}. These results reconfirm the report by Mihara et al. (2004) using Ginga,
who observed a single absorption at ~16 keV in a minor (~10^{37} erg s^{-1})
outburst of this object. The luminosity-dependent cyclotron resonance energy
may be understood as a result of a decrease in the accretion column height, in
response to a decrease in the mass accretion rate.

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The categories of this paper are: alg-geom
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The categories of this paper are: acc-phys
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The categories of this paper are: chem-ph
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The categories of this paper are: stat
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The categories of this paper are: cs
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The categories of this paper are: nlin
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The categories of this paper are: hep-lat
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The categories of this paper are: chao-dyn
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The categories of this paper are: q-alg
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The categories of this paper are: physics
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The categories of this paper are: ao-sci
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The categories of this paper are: funct-an
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The categories of this paper are: nucl-ex
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The categories of this paper are: quant-ph
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The categories of this paper are: econ
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The categories of this paper are: plasm-ph