Determination of the dynamical parameters of the Universe and its age
Abstract
We determine the density parameters $\Omega_m$ of gravitating matter and $\Omega_{\Lambda}$ of vacuum energy, by making a $\chi^2$ fit to nine independent astrophysical constraints. Paying rigorous attention to statistical detail, we find that the present best values are $\Omega_m=0.31\pm 0.07, \Omega_{\Lambda}=0.70\pm 0.13$, where these $1\sigma$ errors are approximately Gaussian (thus trivially convertible to whatever percentage confidence range desired). The total $\chi^2$ is 2.5 for 7 degrees of freedom, testifying that the various systematic errors included are generous. Since $\Omega_m + \Omega_{\Lambda}= 1.01\pm 0.15$, it follows that the Einsteinde Sitter model is very strongly ruled out, that also any lowdensity model with $\Omega_{\Lambda}=0$ is ruled out, and that a flat cosmology is not only possible, but clearly preferred. In the flat case we find $\Omega_m=0.31\pm 0.04$, from which it follows that the age of the Universe is $t_0 = 13.7^{+1.2}_{1.1}(0.68/h)$ Gyr.
 Publication:

arXiv eprints
 Pub Date:
 January 1999
 DOI:
 10.48550/arXiv.astroph/9901234
 arXiv:
 arXiv:astroph/9901234
 Bibcode:
 1999astro.ph..1234R
 Keywords:

 Astrophysics
 EPrint:
 17 Pages, 1 Figure, LaTeX2e