Wilkinson Microwave Anisotropy Probe

The data made available through this page has been updated. The most recent version of this data may be accessed through /product/map/current/

Product Name
Cosmological Parameters


Analysis of the WMAP data involved the computation of cosmological parameters assuming a variety of models and including a variety of datasets in addition to the WMAP dataset. The various model/dataset combinations that were tested are displayed in a matrix; the combinations that were analyzed have links in the corresponding cells to individual display pages that show the cosmological parameters computed using that combination of model and dataset. A printable version of each list of parameters is made available as a Postscript file through a link its corresponding the individual display page.

Mnemonics are used to identify the models and datasets in the table and the individual model/dataset displays. The following table translate the mnemonics:

Mnemonic Description
lcdm ΛCDM
lcdm+kcutlin ΛCDM + primordial spectrum with sharp cutoff and linear prior
lcdm+kcutlog ΛCDM + primordial spectrum with sharp cutoff and log prior
lcdm+mnu ΛCDM + massive neutrinos
lcdm+mnu+nrel ΛCDM + massive neutrinos + number of relativistic species
lcdm+nrel ΛCDM + number of relativistic species
lcdm+ns=1 ΛCDM + scale invariant fluctuations (ns=1)
lcdm+run ΛCDM + running scalar spectral index
lcdm+run+tens ΛCDM + running spectral index + Tensor Modes
lcdm+sz=0 ΛCDM with the SZ amplitude set to zero.
lcdm+tau=0 ΛCDM + no reionization (τ=0)
lcdm+tens ΛCDM + Tensor Modes
lcdm+xe1step ΛCDM + step reionization
m2phi2 ΛCDM assuming m2&phi2 inflation with N=60 e-folds.
ocdm Open CDM
ocdm+omegac=0 Open CDM + No Dark Matter (Ωc=0, ΩΛ≠0)
ocdm+omegal=0 Open CDM + No Cosmological Constant (Ωc≠0, ΩΛ=0)
ocdm+w Open CDM + w, (w = constant)
pkrec primordial spectrum freely varying in 15 bins in k space
wcdm+mnu wCDM + massive neutrinos, (w = constant)
wcdm+nopert wCDM + no perturbtaions, (w = constant)
wcdm+pert wCDM + perturbations, (w = constant)
wmap WMAP 3 year data set
2df 2dF Galaxy Redshift Survey (Cole, et.al., 2005)
bao Baryonic Acoustic Oscillations (Eisenstein, et.al., 2005)
boom+acbar BOOMERanG + ACBAR (Montroy, et.al., 2005, Kuo, et.al., 2004)
cbi+vsa CBI + VSA (Readhead, et.al., 2004, Dickinson, et.al., 2004)
hst Hubble Space Telescope Key Project (Freedman, et.al., 2001)
sdss Sloan Digital Sky Survey, (Tegmark, et.al., 2004; Eisenstein, et.al., 2005)
sn astier Supernova Legacy Survey (SNLS) (Astier, et.al., 2005)
sn gold Supernova "Gold Sample" (Riess, et.al., 2004)
wl Weak Lensing (Semboloni, et.al., 2005; Hoekstra, et.al., 2005)
all All data sets combined, excludes BAO, HST and Weak Lensing

As mentioned previously, each model/dataset combination has an individual display page that shows the WMAP measurements of the cosmological parameters, with a link to a Postscript file showing the same parameters. These display pages also contain links to files containing WMAP's best fit Cl's, best fit matter power spectra, and Monte Carlo Markov Chains. The Markov Chain are supplied in a compressed tarball that contains a README file describing the contents. The spectra files contain:

  • Best fit Cl scalar files contain four columns: l, TT, EE, and TE. The tensor and total files contain five columns: l, TT, EE, BB, and TE. The Cl columns are scaled: T02 l (l + 1) Cl / 2&pi in µK2;
  • Best fit matter power spectra files contain two columns. The first column is k/h in units of Mpc-1. The second column is the linear matter power spectrum P(k), defined such that the variance is: σ2 = (2π)-3 ∫d3k P(k)

Additional Information

  • Cole, et.al., 2005, MNRAS, 362, 505
  • Eisenstein, et.al., 2005, ApJ, 633, 560
  • Montroy, et.al., 2005, ApJ, submitted
  • Kuo, et.al., 2004, ApJ, 600, 32
  • Readhead, et.al., 2004, ApJ, 609, 498
  • Dickinson, et.al., 2004, MNRAS, 353, 732
  • Freedman, et.al., 2004, ApJ, 553, 47
  • Tegmark, et.al., 2004, ApJ, 606, 702
  • Astier, et.al., 2006, AA, 447, 31
  • Riess, et.al., 2004, ApJ, 607, 665
  • Semboloni, et.al., 2005, ApJ, submitted
  • Hoekstra, et.al., 2005, ApJ, submitted

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Goddard Space Flight Center, National Aeronautics and Space Administration
HEASARC Director: Dr. Alan P. Smale
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