Superhorizon perturbations and the cosmic microwave background
Superhorizon perturbations induce large-scale temperature anisotropies in the cosmic microwave background (CMB) via the Grishchuk-Zel'dovich effect. We analyze the CMB temperature anisotropies generated by a single-mode adiabatic superhorizon perturbation. We show that an adiabatic superhorizon perturbation in a LambdaCDM universe does not generate a CMB temperature dipole, and we derive constraints to the amplitude and wavelength of a superhorizon potential perturbation from measurements of the CMB quadrupole and octupole. We also consider constraints to a superhorizon fluctuation in the curvaton field, which was recently proposed as a source of the hemispherical power asymmetry in the CMB.
Additional Information© 2008 The American Physical Society. (Received 11 August 2008; published 30 October 2008) We thank Chris Hirata and Mike Kesden for useful discussions. This work was supported by DOE DE-FG03-92-ER40701 and the Gordon and Betty Moore Foundation
Published - ERIprd08.pdf