Testing the local-void alternative to dark energy using galaxy pairs
  The possibility that we live in a special place in the universe, close to the
center of a large, radially inhomogeneous void, has attracted attention
recently as an alternative to dark energy or modified gravity to explain the
accelerating universe. We show that the distribution of orientations of galaxy
pairs can be used to test the Copernican principle that we are not in a central
or special region of Universe. The popular void models can not fit both the
latest type Ia supernova, cosmic microwave background data and the distribution
of orientations of galaxy pairs simultaneously. Our results rule out the void
models at the $4\sigma$ confidence level as the origin of cosmic acceleration
and favor the Copernican principle.
