Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: 3-5 micron spectroscopy of obscured AGNs in ULIRGs   We present the results of infrared L-band (3-4 micron) and M-band (4-5
micron) VLT-ISAAC spectroscopy of five bright Ultraluminous InfraRed Galaxies
(ULIRGs) hosting an AGN. From our analysis we distinguish two types of sources:
ULIRGs where the AGN is unobscured (with a flat continuum and no absorption
features at 3.4 micron and 4.6 micron), and those with highly obscured AGNs
(with a steep, reddened continuum and absorption features due to hydrocarbons
and CO). Starburst activity is also present in all of the sources as inferred
from the 3.3 micron PAH emission line. A strong correlation is found between
continuum slope and CO optical depth, which suggests that deep carbon monoxide
absorption is a common feature of highly obscured ULIRG AGN. Finally we show
that the AGN dominates the 3-4 micron emission, even if its contribution to the
bolometric luminosity is small.

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The categories of this paper are: q-bio
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The categories of this paper are: q-fin
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The categories of this paper are: comp-gas
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The categories of this paper are: hep-th
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The categories of this paper are: nucl-ex
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The categories of this paper are: hep-lat
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The categories of this paper are: stat
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The categories of this paper are: cmp-lg
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The categories of this paper are: acc-phys
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The categories of this paper are: math
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The categories of this paper are: q-alg
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The categories of this paper are: solv-int
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The categories of this paper are: ao-sci
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The categories of this paper are: nucl-th
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The categories of this paper are: math-ph
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The categories of this paper are: quant-ph