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Astron. Astrophys. 364, 369-376 (2000)

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Cosmological constraints from the cosmic microwave background

M. Le Dour 1, M. Douspis 1, J.G. Bartlett 1 and A. Blanchard 1,2

1 Observatoire Midi-Pyrénées, 14, avenue E. Belin, 31400 Toulouse, France, Unité associée au CNRS, UMR 5572 (http://www.omp.obs-mip.fr/omp )
2 Université Louis Pasteur, 4, rue Blaise Pascal, 67000 Strasbourg, France

Received 20 April 2000 / Accepted 26 July 2000


Using an approximate likelihood method adapted to band-power estimates, we analyze the ensemble of first generation cosmic microwave background anisotropy experiments to deduce constraints over a six-dimensional parameter space describing Inflation-generated adiabatic, scalar fluctuations. The basic preferences of simple Inflation scenarios are consistent with the data set: flat geometries [FORMULA] and a scale-invariant primeval spectrum ([FORMULA]) are favored. Models with significant negative curvature ([FORMULA]) are eliminated, while constraints on postive curvature are less stringent. Degeneracies among the parameters prevent independent determinations of the matter density [FORMULA] and the cosmological constant [FORMULA], and the Hubble constant [FORMULA] remains relatively unconstrained. We also find that the height of the first Doppler peak relative to the amplitude suggested by data at larger l indicates a high baryon content ([FORMULA]), almost independently of the other parameters. Besides the overall qualitative advance expected of the next generation experiments, their improved dipole calibrations will be particularly useful for constraining the peak height. Our analysis includes a Goodness-of-Fit statistic applicable to power estimates and which indicates that the maximum likelihood model provides an acceptable fit to the data set.

Key words: cosmology: cosmic microwave background – cosmology: observations – cosmology: theory

Send offprint requests to: bartlett@ast.obs-mip.fr

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© European Southern Observatory (ESO) 2000

Online publication: January 29, 2001