Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The EXOSAT data on GX 339-4: further evidence for an ``intermediate''
  state   We have studied the fast timing and spectral behavior of the black hole
candidate (BHC) GX 339-4 using all 1 - 20 keV EXOSAT ME data: the July 1983,
March 1984, May 1984 and April 1985 observations. In April 1985 GX 339-4 was in
a weak low state (0.03E-9 erg cm^{-2} s^{-1}, 2 - 10 keV). The X-ray spectrum
was a hard power law with a photon index \alpha of 1.82 and the power spectrum,
though ill-constrained by the data, was consistent with a typical BHC low state
spectrum. During the other three pointings the system was brighter (1.5E-9 erg
cm^{-2} s^{-1}, 2 - 10 keV), an ultrasoft component was present in the
spectrum, and the power law was steeper (\alpha ~3.5 in 1984; in 1983 it was
not well-measured); the power spectrum showed a flat-topped band-limited noise
component with a break frequency of ~4.5 Hz and a fractional rms amplitude of
~7%. Comparing flux levels, X-ray spectra and power spectra we conclude that in
these observations GX 339-4 was in a state intermediate between the usual BHC
low and high states. The system was ~4 times brighter than in its usual low
state, 4 times fainter than in its usual high state, and an order of magnitude
fainter than in its very high state. We compare these results to those recently
obtained on other BHCs, and conclude that this ``intermediate state'' behavior
is a common characteristic of BHCs, that occurs at $\dot M$ levels intermediate
between the high and the low state. We argue that this result can be used to
resolve the long-standing issue of the dependence of the power spectral break
frequency in the low state on mass accretion rate, and strengthens the idea
that low-state noise and very-high state noise may have a common origin. We
briefly discuss a possible interpretation for the changes in break frequency in
the low state and between low state and intermediate state.

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The categories of this paper are: hep-th
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The categories of this paper are: cmp-lg
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The categories of this paper are: chem-ph
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The categories of this paper are: physics
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The categories of this paper are: cond-mat
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The categories of this paper are: alg-geom
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The categories of this paper are: dg-ga
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The categories of this paper are: hep-ph
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The categories of this paper are: acc-phys
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The categories of this paper are: gr-qc
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The categories of this paper are: bayes-an
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The categories of this paper are: ao-sci
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The categories of this paper are: eess
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The categories of this paper are: adap-org
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The categories of this paper are: q-alg
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The categories of this paper are: hep-lat