EDP Sciences
Free access
Volume 373, Number 2, July II 2001
Page(s) 369 - 376
Section Cosmology
DOI http://dx.doi.org/10.1051/0004-6361:20010627

A&A 373, 369-376 (2001)
DOI: 10.1051/0004-6361:20010627

Statistical evaluation of the observational information on $\mathsf{\Omega_{m}}$ and $\mathsf{\Omega_{\rm\Lambda}}$

S. M. Harun-or-Rashid and M. Roos

Physics Department, High Energy Physics Division, POB 64, 00014 University of Helsinki, Finland

(Received 6 February 2001 / Accepted 27 April 2001)

We undertake a critical evaluation of recent observational information on $\Omega_{\rm m}$ and $\Omega_{\rm\Lambda}$ in order to identify possible sources of systematic errors and effects of simplified statistical analyses. We combine observations for which the results have been published in the form of likelihood contours in the $\Omega_{\rm m},\Omega_{\rm\Lambda}$ plane. We approximate the contours by fifth order polynomials, and we then use the maximum likelihood method to obtain joint likelihood contours for the combined data. In the choice of statistical merits we aim at minimum loss of information rather than at minimum variance. We find that $\Omega_{\rm0} = \Omega_{\rm m}+ \Omega_{\rm\Lambda}= 0.99\pm 0.04 \pm 0.03$, where the first error is mainly statistical and the second error is systematical. In a flat Universe we find $\Omega_{\rm m}^{\rm flat} = 0.31 \pm 0.04 \pm 0.04$.

Key words: cosmology: observations -- methods: statistical

Offprint request: S. M. Harun-or-Rashid, hsrashid@pcu.helsinki.fi

© ESO 2001