Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Active Nucleus of IC4970: A Nearby Example of Merger-Induced
  Cold-Gas Accretion   We present results from Chandra X-ray and Spitzer mid-infrared observations
of the interacting galaxy pair NGC6872/IC4970 in the Pavo galaxy group and show
that the smaller companion galaxy IC4970 hosts a highly obscured active
galactic nucleus (AGN). The 0.5-10 keV X-ray luminosity of the nucleus is
variable, increasing by a factor 2.9 to 1.7 x 10^{42} erg/s (bright state) on
~100 ks timescales. The X-ray spectrum of the is heavily absorbed (N_H = 3 x
10^{23} cm^{-2}) for power law models with Gamma = 1.5-2.0 and shows a clear
6.4 keV Fe Kalpha line with equivalent width of 144-195 eV. Limits on the
diffuse emission in IC4970 from Chandra X-ray data suggest that the available
power from Bondi accretion of hot interstellar gas may be an order of magnitude
too small to power the AGN. Spitzer images show that 8 micron nonstellar
emission is concentrated in the central 1 kpc of IC4970, consistent with high
obscuration in this region. The mid-infrared colors of the nucleus are
consistent with those expected for a highly obscured AGN. Taken together these
data suggest that the nucleus of IC4970 is a Seyfert 2, triggered and fueled by
cold material supplied to the central supermassive black hole as a result of
the off-axis collision of IC4970 with the cold-gas rich spiral galaxy NGC6872.

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The categories of this paper are: math-ph
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The categories of this paper are: q-alg
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The categories of this paper are: quant-ph
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The categories of this paper are: q-bio
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The categories of this paper are: stat
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The categories of this paper are: hep-lat
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The categories of this paper are: hep-ph
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The categories of this paper are: adap-org
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The categories of this paper are: nlin
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The categories of this paper are: atom-ph
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The categories of this paper are: mtrl-th
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The categories of this paper are: dg-ga
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The categories of this paper are: cond-mat
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The categories of this paper are: hep-th
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The categories of this paper are: solv-int
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The categories of this paper are: alg-geom