First-year Wilkinson Microwave Anisotropy Probe (WMAP) observations:: Implications for inflation

We confront predictions of inflationary scenarios with the Wilkinson Microwave Anisotropy Probe (WMAP) data, in combination with complementary small-scale cosmic microwave background (CMB) measurements and large-scale structure data. The WMAP detection of a large-angle anticorrelation in the temperature-polarization cross-power spectrum is the signature of adiabatic superhorizon fluctuations at the time of decoupling. The WMAP data are described by pure adiabatic fluctuations: we place an upper limit on a correlated cold dark matter (CDM) isocurvature component. Using WMAP constraints on the shape of the scalar power spectrum and the amplitude of gravity waves, we explore the parameter space of inflationary models that is consistent with the data. We place limits on inflationary models; for example, a minimally coupled lambdaphi(4) is disfavored at more than 3 sigma using WMAP data in combination with smaller scale CMB and large-scale structure survey data. The limits on the primordial parameters using WMAP data alone are n(s)(k(0)=0.002 Mpc(-1))=1.20(-0.11)(+0.12), dn(s)/d ln k=-0.077(-0.052)(+0.050), A(k(0)=0.002 Mpc(-1))=0.71(-0.11)(+0.10) (68% CL), and r(k(0)=0.002 Mpc(-1))<1.28 (95% CL).