### WMAP Results

WMAP has released their 2^{nd} and 3^{rd} year data.

The measurements of the CMBR anisotropy show clear signs of the 3^{rd} acoustic peak.

On the subject of polarization, they find no evidence for $B$-modes and an upper limit on the scalar/tensor ratio, $r=\lesssim 0.55$, which is getting close to the predictions of simple inflationary models, $r\sim 0.3$.

The fit to the ΛCDM model has improved markedly over the first year results.

Parameter | WMAP Only | WMAP +CBI+VSA | WMAP +ACBAR +BOOMERanG | WMAP +2dFGRS |
---|---|---|---|---|

$100\Omega_b h^2$ | $2.233\left.\scriptsize{\array{\arrayopts{\align{center}\colalign{left}} +0.072\\ -0.091}}\right.$ | $2.203\left.\scriptsize{\array{\arrayopts{\align{center}\colalign{left}} +0.072\\ -0.090}}\right.$ | $2.228\left.\scriptsize{\array{\arrayopts{\align{center}\colalign{left}} +0.066\\ -0.082}}\right.$ | $2.223\left.\scriptsize{\array{\arrayopts{\align{center}\colalign{left}} +0.066\\ -0.083}}\right.$ |

$\Omega_m h^2$ | $0.1268\left.\scriptsize{\array{\arrayopts{\align{center}\colalign{left}} +0.0073\\ -0.0128}}\right.$ | $0.1238\left.\scriptsize{\array{\arrayopts{\align{center}\colalign{left}} +0.0066\\ -0.0118}}\right.$ | $0.1271\left.\scriptsize{\array{\arrayopts{\align{center}\colalign{left}} +0.0070\\ -0.0128}}\right.$ | $0.1262\left.\scriptsize{\array{\arrayopts{\align{center}\colalign{left}} +0.0050\\ -0.0103}}\right.$ |

$h$ | $0.734\left.\scriptsize{\array{\arrayopts{\align{center}\colalign{left}} +0.028\\ -0.038}}\right.$ | $0.738\left.\scriptsize{\array{\arrayopts{\align{center}\colalign{left}} +0.028\\ -0.037}}\right.$ | $0.733\left.\scriptsize{\array{\arrayopts{\align{center}\colalign{left}} +0.030\\ -0.038}}\right.$ | $0.732\left.\scriptsize{\array{\arrayopts{\align{center}\colalign{left}} +0.018\\ -0.025}}\right.$ |

$A$ | $0.801\left.\scriptsize{\array{\arrayopts{\align{center}\colalign{left}} +0.043\\ -0.054}}\right.$ | $0.798\left.\scriptsize{\array{\arrayopts{\align{center}\colalign{left}} +0.047\\ -0.057}}\right.$ | $0.801\left.\scriptsize{\array{\arrayopts{\align{center}\colalign{left}} +0.048\\ -0.056}}\right.$ | $0.799\left.\scriptsize{\array{\arrayopts{\align{center}\colalign{left}} +0.042\\ -0.051}}\right.$ |

$\tau$ | $0.088\left.\scriptsize{\array{\arrayopts{\align{center}\colalign{left}} +0.028\\ -0.034}}\right.$ | $0.084\left.\scriptsize{\array{\arrayopts{\align{center}\colalign{left}} +0.031\\ -0.038}}\right.$ | $0.084\left.\scriptsize{\array{\arrayopts{\align{center}\colalign{left}} +0.027\\ -0.034}}\right.$ | $0.083\left.\scriptsize{\array{\arrayopts{\align{center}\colalign{left}} +0.027\\ -0.031}}\right.$ |

$n_s$ | $0.951\left.\scriptsize{\array{\arrayopts{\align{center}\colalign{left}} +0.015\\ -0.019}}\right.$ | $0.945\left.\scriptsize{\array{\arrayopts{\align{center}\colalign{left}} +0.015\\ -0.019}}\right.$ | $0.949\left.\scriptsize{\array{\arrayopts{\align{center}\colalign{left}} +0.015\\ -0.019}}\right.$ | $0.948\left.\scriptsize{\array{\arrayopts{\align{center}\colalign{left}} +0.014\\ -0.018}}\right.$ |

$\sigma_8$ | $0.744\left.\scriptsize{\array{\arrayopts{\align{center}\colalign{left}} +0.050\\ -0.060}}\right.$ | $0.722\left.\scriptsize{\array{\arrayopts{\align{center}\colalign{left}} +0.044\\ -0.056}}\right.$ | $0.742\left.\scriptsize{\array{\arrayopts{\align{center}\colalign{left}} +0.045\\ -0.057}}\right.$ | $0.737\left.\scriptsize{\array{\arrayopts{\align{center}\colalign{left}} +0.033\\ -0.045}}\right.$ |

$\Omega_m$ | $0.238\left.\scriptsize{\array{\arrayopts{\align{center}\colalign{left}} +0.027\\ -0.045}}\right.$ | $0.229\left.\scriptsize{\array{\arrayopts{\align{center}\colalign{left}} +0.026\\ -0.042}}\right.$ | $0.239\left.\scriptsize{\array{\arrayopts{\align{center}\colalign{left}} +0.025\\ -0.046}}\right.$ | $0.236\left.\scriptsize{\array{\arrayopts{\align{center}\colalign{left}} +0.016\\ -0.029}}\right.$ |

- $\Omega_b=$ (fractional) energy density in baryons
- $\Omega_m=$ (fractional) energy density in matter $=\Omega_b+\Omega_\nu +\Omega_{CDM}$
- $n_s=$ spectral density of scalar fluctuations
- $h=H_0/(100 km/s/Mpc)$
- $A=$ amplitude of density fluctuations ($k = 0.002$/Mpc)
- $\tau=$ reionization optical depth
- $\sigma_8=$ linear theory amplitude of matter fluctuations at $8h^{-1}$ Mpc

The full list of papers, doubtless contains more nuggets of information. Perhaps our cosmologist friends over at CosmicVariance will provide some insight.

Posted by distler at March 16, 2006 1:44 PM
## Re: WMAP Results

Jacques,

Just a heads-up: The WMAP Power Spectrum picture (the first one on your post) does not seem to be showing… and, in fact, if you try to actually open the image file, it complains that the file does not exist.

[]’s.