SEVEN-YEAR <i>WILKINSON MICROWAVE ANISOTROPY PROBE</i> ( <i>WMAP</i> ) OBSERVATIONS: SKY MAPS, SYSTEMATIC ERRORS, AND BASIC RESULTS

Abstract

(Abridged) New full sky temperature and polarization maps based on seven\nyears of data from WMAP are presented. The new results are consistent with\nprevious results, but have improved due to reduced noise from the additional\nintegration time, improved knowledge of the instrument performance, and\nimproved data analysis procedures. The improvements are described in detail.\nThe seven year data set is well fit by a minimal six-parameter flat Lambda-CDM\nmodel. The parameters for this model, using the WMAP data in conjunction with\nbaryon acoustic oscillation data from the Sloan Digital Sky Survey and priors\non H_0 from Hubble Space Telescope observations, are: Omega_bh^2 = 0.02260\n+-0.00053, Omega_ch^2 = 0.1123 +-0.0035, Omega_Lambda = 0.728 +0.015 -0.016,\nn_s = 0.963 +-0.012, tau = 0.087 +-0.014 and sigma_8 = 0.809 +-0.024 (68 % CL\nuncertainties). The temperature power spectrum signal-to-noise ratio per\nmultipole is greater that unity for multipoles &lt; 919, allowing a robust\nmeasurement of the third acoustic peak. This measurement results in improved\nconstraints on the matter density, Omega_mh^2 = 0.1334 +0.0056 -0.0055, and the\nepoch of matter- radiation equality, z_eq = 3196 +134 -133, using WMAP data\nalone. The new WMAP data, when combined with smaller angular scale microwave\nbackground anisotropy data, results in a 3 sigma detection of the abundance of\nprimordial Helium, Y_He = 0.326 +-0.075.The power-law index of the primordial\npower spectrum is now determined to be n_s = 0.963 +-0.012, excluding the\nHarrison-Zel'dovich-Peebles spectrum by &gt;3 sigma. These new WMAP measurements\nprovide important tests of Big Bang cosmology.\n