Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: H.E.S.S. upper limit on the very high energy gamma-ray emission from the
  globular cluster 47 Tucanae   Observations of the globular cluster 47 Tucanae (NGC 104), which contains at
least 23 millisecond pulsars, were performed with the H.E.S.S. telescope
system. The observations lead to an upper limit of F(E>800 GeV) < 6.7e-13 /
cm^2 s on the integral gamma-ray photon flux from 47 Tucanae. Considering
millisecond pulsars as the unique potential source of gamma-rays in the
globular cluster, constraints based on emission models are derived: on the
magnetic field in the average pulsar nebula and on the conversion efficiency of
spin-down power to gamma-ray photons or to relativistic leptons.

25
The categories of this paper are: patt-sol
37
The categories of this paper are: supr-con
35
The categories of this paper are: mtrl-th
5
The categories of this paper are: gr-qc
11
The categories of this paper are: hep-lat
33
The categories of this paper are: plasm-ph
20
The categories of this paper are: acc-phys
17
The categories of this paper are: q-fin
16
The categories of this paper are: stat
9
The categories of this paper are: nlin
23
The categories of this paper are: solv-int
10
The categories of this paper are: q-bio
8
The categories of this paper are: hep-ex
28
The categories of this paper are: alg-geom
1
The categories of this paper are: cs
13
The categories of this paper are: quant-ph