Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Gamma-ray flares in the Crab Nebula: A case of relativistic
  reconnection?   The Crab Nebula was formed after the collapse of a massive star about a
thousand years ago, leaving behind a pulsar that inflates a bubble of
ultra-relativistic electron-positron pairs permeated with magnetic field. The
observation of brief but bright flares of energetic gamma rays suggests that
pairs are accelerated to PeV energies within a few days; such rapid
acceleration cannot be driven by shocks. Here, it is argued that the flares may
be the smoking gun of magnetic dissipation in the Nebula. Using 2D and 3D
particle-in-cell simulations, it is shown that the observations are consistent
with relativistic magnetic reconnection, where pairs are subject to strong
radiative cooling. The Crab flares may highlight the importance of relativistic
magnetic reconnection in astrophysical sources.

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The categories of this paper are: hep-ph
16
The categories of this paper are: stat
19
The categories of this paper are: eess
14
The categories of this paper are: math-ph
4
The categories of this paper are: cond-mat
23
The categories of this paper are: solv-int
31
The categories of this paper are: ao-sci
11
The categories of this paper are: hep-lat
21
The categories of this paper are: adap-org
25
The categories of this paper are: patt-sol
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The categories of this paper are: q-fin
34
The categories of this paper are: chem-ph
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The categories of this paper are: econ
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The categories of this paper are: cs
27
The categories of this paper are: comp-gas
28
The categories of this paper are: alg-geom