Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: ULTRACAM observations of the black hole X-ray transient XTE J1118+480 in
  quiescence   We present high time-resolution multicolour observations of the quiescent
soft X-ray transient XTE J1118+480 obtained with ULTRACAM. Superimposed on the
double-humped continuum g' and i'-band lightcurves are rapid flare events which
typically last a few minutes. The power density spectrum of the lightcurves can
be described by a broken power-law model with a break frequency at ~2 mHz or a
power-law model plus a broad quasi-periodic oscillation (QPO) at ~2 mHz. In the
context of the cellular-automaton we estimate the size of the quiescent
advection-dominated flow (ADAF) region to be ~10^4 Schwarzschild radii, similar
to that observed in other quiescent black hole X-ray transients, suggesting the
same underlying physics. The similarites between the low/hard and quiescent
state PDS suggest a similar origin for the optical and X-ray variability, most
likely from regions at/near the ADAF.

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The categories of this paper are: math-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: bayes-an
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The categories of this paper are: acc-phys
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The categories of this paper are: physics
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The categories of this paper are: solv-int
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The categories of this paper are: patt-sol
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The categories of this paper are: gr-qc
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The categories of this paper are: hep-lat
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The categories of this paper are: nlin
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The categories of this paper are: cmp-lg
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The categories of this paper are: hep-ex
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The categories of this paper are: quant-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: cs
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The categories of this paper are: q-fin