Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Long-term X-ray variability and state transition of GX 339-4   With extensive monitoring data spanning over 30 years from Vela 5B, Ariel 5,
Ginga, Compton Gamma Ray Observatory, Rossi X-ray Timing Explorer and BeppoSAX,
we find evidence for long-term X-ray variability on timescales ~190-240 d from
the black hole low-mass X-ray binary system GX 339-4. Such variability
resembles the outburst cycle of Z Cam-type dwarf novae, in which the standard
disc instability model plays a crucial role. If such a model is applicable to
GX 339-4, then the observed variability might be due to the irradiation of an
unstable accretion disc. We show that within the framework of the X-ray
irradiation model, when the accretion rate exceeds a critical value, GX 339-4
enters a `flat-topped' high/soft state, such as seen in 1998, which we suggest
corresponds to the `standstill' state of Z Cam systems.

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The categories of this paper are: comp-gas
10
The categories of this paper are: q-bio
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The categories of this paper are: eess
29
The categories of this paper are: funct-an
2
The categories of this paper are: math
14
The categories of this paper are: math-ph
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The categories of this paper are: atom-ph
3
The categories of this paper are: physics
15
The categories of this paper are: nucl-ex
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The categories of this paper are: hep-ex
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The categories of this paper are: adap-org
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The categories of this paper are: patt-sol
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The categories of this paper are: supr-con
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The categories of this paper are: nucl-th
9
The categories of this paper are: nlin
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The categories of this paper are: chao-dyn