First‐Year Wilkinson Microwave Anisotropy Probe ( WMAP ) Observations: Implications For Inflation

We confront predictions of inflationary scenarios with the WMAP data, incombination with complementary small-scale CMB measurements and large-scalestructure data. The WMAP detection of a large-angle anti-correlation in thetemperature--polarization cross-power spectrum is the signature of adiabaticsuperhorizon fluctuations at the time of decoupling. The WMAP data aredescribed by pure adiabatic fluctuations: we place an upper limit on acorrelated CDM isocurvature component. Using WMAP constraints on the shape ofthe scalar power spectrum and the amplitude of gravity waves, we explore theparameter space of inflationary models that is consistent with the data. Weplace limits on inflationary models; for example, a minimally-coupled lambdaphi^4 is disfavored at more than 3-sigma using WMAP data in combination withsmaller scale CMB and large scale structure survey data. The limits on theprimordial parameters using WMAP data alone are: n_s(k_0=0.002Mpc^{-1})=1.20_{-0.11}^{+0.12}, dn/dlnk=-0.077^{+0.050}_{- 0.052}, A(k_0=0.002Mpc}^{-1})=0.71^{+0.10}_{-0.11} (68% CL), and r(k_0=0.002 Mpc^{-1})<1.28 (95%CL).