Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Search for Magnetically Broadened Cascade Emission From Blazars with
  VERITAS   We present a search for magnetically broadened gamma-ray emission around
active galactic nuclei (AGN), using VERITAS observations of seven hard-spectrum
blazars. A cascade process occurs when multi-TeV gamma rays from AGN interact
with extragalactic background light (EBL) photons to produce electron-positron
pairs, which then interact with cosmic microwave background (CMB) photons via
inverse-Compton scattering to produce gamma rays. Due to the deflection of the
electron-positron pairs, a non-zero intergalactic magnetic field (IGMF) would
potentially produce detectable effects on the angular distribution of the
cascade emission. In particular, an angular broadening compared to the
unscattered emission could occur. Through non-detection of angularly broadened
emission from 1ES 1218+304, the source with the largest predicted cascade
fraction, we exclude a range of IGMF strengths around $10^{-14}$G at the 95%
confidence level. The extent of the exclusion range varies with the assumptions
made about the intrinsic spectrum of 1ES 1218+304 and the EBL model used in the
simulation of the cascade process. All of the sources are used to set limits on
the flux due to extended emission.

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The categories of this paper are: patt-sol
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The categories of this paper are: q-fin
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The categories of this paper are: funct-an
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The categories of this paper are: alg-geom
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The categories of this paper are: nucl-th
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The categories of this paper are: q-alg
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The categories of this paper are: plasm-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: quant-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: adap-org
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The categories of this paper are: stat
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The categories of this paper are: supr-con
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The categories of this paper are: gr-qc
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The categories of this paper are: hep-ph
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The categories of this paper are: q-bio