Dipoles in the Sky
  We perform observational tests of statistical isotropy using data from
large-scale structure surveys spanning a wide range of wavelengths. Using data
from 2MASS, 2MRS, and NVSS galaxies, and BATSE gamma-ray bursts, we constrain
the amplitude and direction of dipolar modulations in the number count of
sources projected along the line of sight. We pay particular attention to the
treatment of systematic errors and selection effects, and carefully distinguish
between different sources of dipole signal previously considered in the
literature. Dipole signals detected in these surveys are consistent with the
standard, statistically isotropic expectation, except for the NVSS result,
which is likely biased by remaining systematics in the data. We place
constraints on the amplitude of any intrinsic dipole driven by novel physics in
the early universe.
