Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Discovery of TeV gamma-ray emission from the pulsar wind nebula 3C 58 by
  MAGIC   The pulsar wind nebula (PWN) 3C 58 is one of the historical very-high-energy
(VHE; E>100 GeV) gamma-ray source candidates. It is energized by one of the
highest spin-down power pulsars known (5% of Crab pulsar) and it has been
compared to the Crab Nebula due to their morphological similarities. This
object was previously observed by imaging atmospheric Cherenkov telescopes
(Whipple, VERITAS and MAGIC), although not detected, with an upper limit of
2.4% Crab Unit (C.U.) at VHE. It was detected by Fermi-LAT with a spectrum
extending beyond 100 GeV. We analyzed 81 hours of 3C 58 data taken with the
MAGIC telescopes and we detected VHE gamma-ray emission with a significance of
5.7 sigma and an integral flux of 0.65% C.U. above 1 TeV. The differential
energy spectrum between 400 GeV and 10 TeV is well described by a power-law
function d\phi/dE=f_0(E/1TeV)^{-Gamma} with
f_0=(2.0\pm0.4_{stat}\pm0.6_{sys})\times10^{-13}cm^{-2}s^{-1}TeV^{-1} and
Gamma=2.4\pm0.2_{stat}\pm0.2_{sys}. The skymap is compatible with an unresolved
source. We report the first significant detection of PWN 3C 58 at TeV energies.
According to our results 3C 58 is the least luminous VHE gamma-ray PWN ever
detected at VHE and the one with the lowest flux at VHE to date. We compare our
results with the expectations of time-dependent models in which electrons
up-scatter photon fields. The best representation favors a distance to the PWN
of 2 kpc and Far Infrared (FIR) comparable to CMB photon fields. If we consider
an unexpectedly high FIR density, the data can also be reproduced by models
assuming a 3.2 kpc distance. A low magnetic field, far from equipartition, is
required to explain the VHE data. Hadronic contribution from the hosting
supernova remnant (SNR) requires unrealistic energy budget given the density of
the medium, disfavoring cosmic ray acceleration in the SNR as origin of the VHE
gamma-ray emission.

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The categories of this paper are: chem-ph
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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: cond-mat
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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: patt-sol
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The categories of this paper are: supr-con
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The categories of this paper are: q-alg
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The categories of this paper are: physics
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The categories of this paper are: hep-ph
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The categories of this paper are: mtrl-th
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The categories of this paper are: quant-ph
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The categories of this paper are: nucl-th
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The categories of this paper are: dg-ga
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The categories of this paper are: hep-ex