Electric dipole moment of top quark and CP-violating asymmetries in gamma gamma -> t tbar

CP-violating asymmetries due to a possible electric dipole interaction of the top quark in the production and subsequent decay of top quark-top antiquark pair in photon-photon collisions are studied. The asymmetries defined can be used to determine the imaginary part of the electric dipole form factors. A gamma-gamma collider with photon beams generated from laser back-scattering off electron beams with an integrated geometric luminosity of 20 fb^{-1} can put a limit of the order of 10^{-17} e cm on the imaginary part of the electric dipole form factor of the top quark if the electron beams have longitudinal polarization and the laser beams have circular polarization.