Credits

First WMAP article :
Authors: E. Komatsu, K. M. Smith, J. Dunkley, C. L. Bennett, B. Gold, G.
Hinshaw, N. Jarosik, D. Larson, M. R. Nolta, L. Page, D. N. Spergel, M.
Halpern, R. S. Hill, A. Kogut, M. Limon, S. S. Meyer, N. Odegard, G. S.
Tucker, J. L. Weiland, E. Wollack, E. L. Wright

Second WMAP article :
Authors: D. Larson, J. Dunkley, G. Hinshaw, E. Komatsu, M. R. Nolta, C. L.
  Bennett, B. Gold, M. Halpern, R. S. Hill, N. Jarosik, A. Kogut, M. Limon, S.
  S. Meyer, N. Odegard, L. Page, K. M. Smith, D. N. Spergel, G. S. Tucker, J.
  L. Weiland, E. Wollack, E. L. Wright

Third WMAP article :
Authors: N. Jarosik, C. L. Bennett, J. Dunkley, B. Gold, M. R. Greason, M.
  Halpern, R. S. Hill, G. Hinshaw, A. Kogut, E. Komatsu, D. Larson, M. Limon,
  S. S. Meyer, M. R. Nolta, N. Odegard, L. Page, K. M. Smith, D. N. Spergel, G.
  S. Tucker, J. L. Weiland, E. Wollack, E. L. Wright

Fourth WMAP article :
Authors: C. L. Bennett (JHU), R. S. Hill (ADNET), G. Hinshaw (NASA/GSFC), D. Larson (JHU), K. M. Smith (Princeton), J. Dunkley (Oxford), B. Gold (JHU), M. Halpern (UBC), N. Jarosik (Princeton), A. Kogut (NASA/GSFC), E. Komatsu (U. Texas), M. Limon (Columbia), S. S. Meyer (U. Chicago), M. R. Nolta (CITA), N. Odegard (ADNET), L. Page (Princeton), D. N. Spergel (Princeton), G. S. Tucker (Brown), J. L. Weiland (ADNET), E. Wollack (NASA/GSFC), E. L. Wright (UCLA)

WMAP Spacecraft ( picture ):
NASA / WMAP Science Team

Timeline of the Universe ( picture ): NASA / WMAP Science Team


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Cosmological Interpretation The 7-year WMAP data and improved astrophysical data rigorously tests the standard cosmological model and its extensions. By combining WMAP with the latest distance measurements from the Baryon Acoustic Oscillations (BAO) and the Hubble constant (H0) measurement, we determine the parameters of the simplest LCDM model.

The power-law index of the primordial power spectrum is n_s=0.963+-0.012, a measurement that excludes the scale-invariant spectrum by more than 3-sigma. The other parameters, including those beyond the minimal set, are also improved from the 5-year results. Notable examples of improved parameters are the total mass of neutrinos, sum(m_nu)<0.58eV, and the effective number of neutrino species, N_eff=4.34+0.86-0.88, which benefit from better determinations of the third peak and H0. We detect the effect of primordial helium on the temperature power spectrum and provide a new test of big bang nucleosynthesis. We detect, and show on the map for the first time, the
tangential and radial polarization patterns around hot and cold spots of temperature fluctuations, an important test of physical processes at z=1090 and the dominance of adiabatic scalar fluctuations. With the 7-year TB power spectrum, the limit on a rotation of the polarization plane due to potential parity-violating effects has improved to Delta(alpha)=-1.1+-1.3(stat)+-1.5(syst) degrees. We report a significant detection of the SZ effect at the locations of known clusters, and show that the current simulations and analytical calculations overestimate the gas pressure, and do not reproduce the observed gas pressure in clusters of galaxies. This result is consistent with the lower-than-expected SZ power spectrum recently measured by the SPT collaboration.
\\ ( http://arxiv.org/abs/1001.4538 ,  943kb)

Power Spectra and WMAP-Derived Parameters
  We present the angular power spectra derived from the 7-year maps and discuss the cosmological conclusions that can be inferred from WMAP data alone. The third acoustic peak in the TT spectrum is now well measured by WMAP. In the context of a flat LambdaCDM model, this improvement allows us to place tighter constraints on the matter density from WMAP data alone, and on the epoch of matter-radiation equality, The temperature-polarization (TE) spectrum is detected in the 7-year data with a significance of 21 sigma, compared to 13 sigma with the 5-year data. The low-l EE spectrum, a measure of the optical depth due to reionization, is detected at 5.5 sigma significance when averaged over l = 2-7. The BB spectrum, an important probe of gravitational waves from inflation, remains consistent with zero. The upper limit on tensor modes from polarization data alone is a factor of 2 lower with the 7-year data than it was
using the 5-year data (Komatsu et al. 2010). We test the parameter recovery process for bias and find that the scalar spectral index, ns, is biased high, but only by 0.13 sigma, while the remaining parameters are biased by < 0.15 sigma. The improvement in the third peak measurement leads to tighter lower limits from WMAP on the number of relativistic degrees of freedom (e.g., neutrinos) in the early universe: Neff > 2.7 (95% CL). Also, using WMAP data alone, the primordial helium mass fraction is found to be YHe = 0.28+0.14-0.15, and with data from higher-resolution CMB experiments included, we now establish the existence of pre-stellar helium at > 3 sigma (Komatsu et al. 2010).
\\ ( http://arxiv.org/abs/1001.4635 ,  127kb)

Sky Maps, Systematic Errors, and Basic Results
  (Abridged) New full sky temperature and polarization maps based on seven years of data from WMAP are presented. The new results are consistent with previous results, but have improved due to reduced noise from the additional integration time, improved knowledge of the instrument performance, and improved data analysis procedures. The improvements are described in detail. The seven year data set is well fit by a minimal six-parameter flat Lambda-CDM model. The parameters for this model, using the WMAP data in conjunction with baryon acoustic oscillation data from the Sloan Digital Sky Survey and priors on H_0 from Hubble Space Telescope observations, are: Omega_bh2 = 0.02260 +-0.00053, Omega_ch2 = 0.1123 +-0.0035, Omega_Lambda = 0.728 +0.015 -0.016, n_s = 0.963 +-0.012, tau = 0.087 +-0.014 and sigma_8 = 0.809 +-0.024 (68 % CL uncertainties). The temperature power spectrum signal-to-noise ratio per multipole is greater that unity for multipoles < 919, allowing a robust measurement of the third acoustic peak. This measurement results in improved constraints on the matter density, Omega_mh2 = 0.1334 +0.0056 -0.0055, and the epoch of matter- radiation equality, z_eq = 3196 +134 -133, using WMAP data alone. The new WMAP data, when combined with smaller angular scale microwave background anisotropy data, results in a 3 sigma detection of the abundance of primordial Helium, Y_He = 0.326 +-0.075.The power-law index of the primordial power spectrum is now determined to be n_s = 0.963 +-0.012, excluding the Harrison-Zel'dovich-Peebles spectrum by >3 sigma. These new WMAP measurements provide important tests of Big Bang cosmology.
\\ ( http://arxiv.org/abs/1001.4744 ,  1168kb)


Are There Cosmic Microwave Background Anomalies?
  A simple six-parameter LCDM model provides a successful fit to WMAP data, both when the data are analyzed alone and in combination with other cosmological data. Even so, it is appropriate to search for any hints of deviations from the now standard model of cosmology, which includes inflation, dark energy, dark matter, baryons, and neutrinos. The cosmological community has subjected the WMAP data to extensive and varied analyses. While there is widespread agreement as to the overall success of the six-parameter LCDM model, various "anomalies" have been reported relative to that model. In this paper we examine potential anomalies and present analyses and assessments of their significance. In most cases we find that claimed anomalies depend on posterior selection of some aspect or subset of the data. Compared with sky simulations based on the best fit model, one can select for low probability features of the WMAP data. Low probability features are expected, but it is not usually straightforward to determine whether any particular low probability feature is the result of the a posteriori selection or of non-standard cosmology. We examine in detail the properties of the power spectrum with respect to the LCDM model. We examine several potential or previously claimed anomalies in the sky maps and power spectra, including cold spots, low quadrupole power, quadropole-octupole alignment, hemispherical or dipole power asymmetry, and
quadrupole power asymmetry. We conclude that there is no compelling evidence for deviations from the LCDM model, which is generally an acceptable statistical fit to WMAP and other cosmological data. \\ ( http://arxiv.org/abs/1001.4758 ,  407kb)