Structure Beyond the Horizon: Inflationary Origins of the Cosmic Power Asymmetry

          @misc{ pirsa_PIRSA:08100031,
            doi = {10.48660/08100031},
            url = {https://pirsa.org/08100031},
            author = {Erickcek, Adrienne},
            keywords = {Cosmology},
            language = {en},
            title = {Structure Beyond the Horizon: Inflationary Origins of the Cosmic Power Asymmetry},
            publisher = {Perimeter Institute},
            year = {2008},
            month = {oct},
            note = {PIRSA:08100031 see, \url{https://pirsa.org}}
          }
          

Abstract

WMAP measurements of CMB temperature anisotropies reveal a power asymmetry: the average amplitude of temperature fluctuations in one hemisphere is larger than the average amplitude in the opposite hemisphere at the 99% confidence level. This power asymmetry may be generated during inflation by a large-amplitude superhorizon perturbation that causes the mean energy density to vary across the observable Universe. Such a superhorizon perturbation would also induce large-scale temperature anisotropies in the CMB; measurements of the CMB quadrupole and octupole (but not the dipole!) therefore constrain the perturbation\'s amplitude and wavelength. I will show how a superhorizon perturbation in a multi-field inflationary theory, the curvaton model, can produce the observed power asymmetry without generating unacceptable temperature fluctuations in the CMB. I will also discuss how this mechanism for generating the power asymmetry will be tested by forthcoming CMB experiments.