Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Unveiling the nature of the unidentified gamma-ray sources II: radio,
  infrared and optical counterparts of the gamma-ray blazar candidates   A significant fraction (~30%) of the high-energy gamma-ray sources listed in
the second Fermi LAT catalog (2FGL) are still of unknown origin, being not yet
associated with counterparts at low energies. We recently developed a new
association method to identify if there is a gamma-ray blazar candidate within
the positional uncertainty region of a generic 2FGL source. This method is
entirely based on the discovery that blazars have distinct infrared colors with
respect to other extragalactic sources found thanks, to the Wide-field Infrared
Survey Explorer (WISE) all-sky observations. Several improvements have been
also performed to increase the efficiency of our method in recognizing
gamma-ray blazar candidates. In this paper we applied our method to two
different samples, the first constituted by the unidentified gamma-ray sources
(UGSs) while the second by the active galaxies of uncertain type (AGUs), both
listed in the 2FGL. We present a catalog of IR counterparts for ~20% of the
UGSs investigated. Then, we also compare our results on the associated sources
with those present in literature. In addition, we illustrate the extensive
archival research carried out to identify the radio, infrared, optical and
X-ray counterparts of the WISE selected, gamma-ray blazar candidates. Finally,
we discuss the future developments of our method based on ground-based
follow-up observations.

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The categories of this paper are: eess
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The categories of this paper are: physics
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The categories of this paper are: math-ph
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The categories of this paper are: adap-org
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The categories of this paper are: hep-ex
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The categories of this paper are: bayes-an
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The categories of this paper are: atom-ph
5
The categories of this paper are: gr-qc
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The categories of this paper are: econ
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The categories of this paper are: chao-dyn
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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: ao-sci
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The categories of this paper are: dg-ga
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The categories of this paper are: chem-ph
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The categories of this paper are: q-alg