Dark-matter electric and magnetic dipole moments

We consider the consequences of a neutral dark-matter particle with a nonzero electric and/or magnetic dipole moment. Theoretical constraints, as well as constraints from direct searches, precision tests of the standard-model, the cosmic microwave background and matter power spectra, and cosmic gamma rays, are included. We find that a relatively light particle with mass between an MeV and a few GeV and an electric or magnetic dipole as large as $\ensuremath{\sim}3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}16}e\text{ }\text{ }\mathrm{c}\mathrm{m}$ (roughly $1.6\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}{\ensuremath{\mu}}_{B}$) satisfies all experimental and observational bounds. Some of the remaining parameter space may be probed with forthcoming more sensitive direct searches and with the Gamma-Ray Large Area Space Telescope.