Observations of the Large Magellanic Cloud with Fermi
  Context: The Large Magellanic Cloud (LMC) is to date the only normal external
galaxy that has been detected in high-energy gamma rays. High-energy gamma rays
trace particle acceleration processes and gamma-ray observations allow the
nature and sites of acceleration to be studied. Aims: We characterise the
distribution and sources of cosmic rays in the LMC from analysis of gamma-ray
observations. Methods: We analyse 11 months of continuous sky-survey
observations obtained with the Large Area Telescope aboard the Fermi Gamma-Ray
Space Telescope and compare it to tracers of the interstellar medium and models
of the gamma-ray sources in the LMC. Results: The LMC is detected at 33 sigma
significance. The integrated >100 MeV photon flux of the LMC amounts to (2.6
+/- 0.2) * 10^-7 ph/cm2/s which corresponds to an energy flux of (1.6 +/- 0.1)
* 10^-10 erg/cm2/s, with additional systematic uncertainties of ~16%. The
analysis reveals the massive star forming region 30 Doradus as a bright source
of gamma-ray emission in the LMC in addition to fainter emission regions found
in the northern part of the galaxy. The gamma-ray emission from the LMC shows
very little correlation with gas density and is rather correlated to tracers of
massive star forming regions. The close confinement of gamma-ray emission to
star forming regions suggests a relatively short GeV cosmic-ray proton
diffusion length. Conclusions: The close correlation between cosmic-ray density
and massive star tracers supports the idea that cosmic rays are accelerated in
massive star forming regions as a result of the large amounts of kinetic energy
that are input by the stellar winds and supernova explosions of massive stars
into the interstellar medium.
