First‐Year <i>Wilkinson Microwave Anisotropy Probe</i> ( <i>WMAP</i> ) Observations: Implications For Inflation

TLDR

The study confronts inflationary predictions with WMAP data, supplemented by small‑scale CMB and large‑scale structure observations. The authors use WMAP constraints on the scalar power spectrum shape and gravity‑wave amplitude, together with small‑scale CMB and large‑scale structure data, to explore the inflationary model parameter space. WMAP detects a large‑angle temperature–polarization anti‑correlation confirming adiabatic superhorizon fluctuations, fits pure adiabatic models with tight limits on correlated CDM isocurvature, disfavors a minimally‑coupled λφ⁴ model at >3σ, and yields n_s=1.20⁺⁰·¹²₋₀·₁₁, dn/dlnk=−0.077⁺⁰·⁰⁵₀₋₀·⁰⁵₂, A=0.71⁺⁰·¹⁰₋₀·₁₁, and r<1.28 (95% CL).

Abstract

We confront predictions of inflationary scenarios with the WMAP data, in combination with complementary small-scale CMB measurements and large-scale structure data. The WMAP detection of a large-angle anti-correlation 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 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 lambda phi^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/dlnk=-0.077^{+0.050}_{- 0.052}, A(k_0=0.002 Mpc}^{-1})=0.71^{+0.10}_{-0.11} (68% CL), and r(k_0=0.002 Mpc^{-1})<1.28 (95% CL).