Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Detection of X-ray spectral state transitions in mini-outbursts of black
  hole transient GRS 1739-278   We report the detection of the state transitions and hysteresis effect in the
two mini-outbursts of the black hole (BH) transient GRS 1739$-$278 following
its 2014 major outburst. The X-ray spectral evolutions in these two
mini-outbursts are similar to the major outburst, in spite of their peak
luminosities and the outburst durations are one order of magnitude lower. We
found the $L_\mathrm{hard-to-soft}$ and the $L_\mathrm{peak,soft}$ of the
mini-outbursts also follow the correlation previous found in other X-ray
binaries. The $L_\mathrm{hard-to-soft}$ of the mini-outbursts is still higher
than that of the persistent BH binary Cyg X-1, which supports that there is a
link between the maximum luminosity a source can reach in the hard state and
the corresponding non-stationary accretion represented by substantial
rate-of-change in the mass accretion rate during flares/outbursts. The detected
luminosity range of these two mini-outbursts is roughly in 3.5$\times
10^{-5}$-- 0.015 ($D/7.5$ kpc)$^{2}$($M/8M_{\odot}$) $L_\mathrm{Edd}$. The
X-ray spectra of other BH transients at such low luminosities are usually
dominated by a power-law component, and an anti-correlation is observed between
the photon index and the X-ray luminosity below 1\% $L_\mathrm{Edd}$. So the
detection of X-ray spectral state transitions indicates that the accretion flow
evolution in these two mini-outbursts of GRS 1739$-$278 are different from
other BH systems at such low-luminosity regime.

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The categories of this paper are: hep-ph
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The categories of this paper are: bayes-an
3
The categories of this paper are: physics
20
The categories of this paper are: acc-phys
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The categories of this paper are: dg-ga
9
The categories of this paper are: nlin
28
The categories of this paper are: alg-geom
4
The categories of this paper are: cond-mat
10
The categories of this paper are: q-bio
29
The categories of this paper are: funct-an
33
The categories of this paper are: plasm-ph
32
The categories of this paper are: atom-ph
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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: mtrl-th
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The categories of this paper are: solv-int