Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Fermi-LAT upper limits on gamma-ray emission from colliding wind
  binaries   Context: Colliding wind binaries (CWBs) are thought to give rise to a
plethora of physical processes including acceleration and interaction of
relativistic particles. Observation of synchrotron radiation in the radio band
confirms there is a relativistic electron population in CWBs. Accordingly, CWBs
have been suspected sources of high-energy gamma-ray emission since the COS-B
era. Theoretical models exist that characterize the underlying physical
processes leading to particle acceleration and quantitatively predict the
non-thermal energy emission observable at Earth. Aims: We strive to find
evidence of gamma-ray emission from a sample of seven CWB systems: WR 11, WR
70, WR 125, WR 137, WR 140, WR 146, and WR 147. Theoretical modelling
identified these systems as the most favourable candidates for emitting
gamma-rays. We make a comparison with existing gamma-ray flux predictions and
investigate possible constraints. Methods: We used 24 months of data from the
Large Area Telescope (LAT) on-board the Fermi Gamma Ray Space Telescope to
perform a dedicated likelihood analysis of CWBs in the LAT energy range.
Results: We find no evidence of gamma-ray emission from any of the studied CWB
systems and determine corresponding flux upper limits. For some CWBs the
interplay of orbital and stellar parameters renders the Fermi-LAT data not
sensitive enough to constrain the parameter space of the emission models. In
the cases of WR140 and WR147, the Fermi-LAT upper limits appear to rule out
some model predictions entirely and constrain theoretical models over a
significant parameter space. A comparison of our findings to the CWB eta Car is
made.

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The categories of this paper are: cs
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The categories of this paper are: econ
21
The categories of this paper are: adap-org
0
The categories of this paper are: hep-ph
26
The categories of this paper are: bayes-an
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The categories of this paper are: nucl-ex
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The categories of this paper are: patt-sol
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The categories of this paper are: nlin
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The categories of this paper are: q-fin
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The categories of this paper are: eess
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The categories of this paper are: nucl-th
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The categories of this paper are: gr-qc
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The categories of this paper are: stat
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The categories of this paper are: math
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The categories of this paper are: acc-phys
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The categories of this paper are: mtrl-th