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Astron. Astrophys. 322, 365-374 (1997)

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Constraints on h, [FORMULA] and [FORMULA] from cosmic microwave background observations

Charles H. Lineweaver 1, Domingos Barbosa 1, 2, Alain Blanchard 1 and James G. Bartlett 1

1 Observatoire de Strasbourg, F-67000 Strasbourg, France
2 Centro de Astrofísica da U.P., Rua do Campo Alegre 823, 4150 Porto, Portugal

Received 1 August 1996 / Accepted 25 October 1996


In this paper we compare data to theory. We use a compilation of the most recent cosmic microwave background (CMB) measurements to constrain Hubble's constant h, the baryon fraction [FORMULA], and the cosmological constant [FORMULA]. We fit h -, [FORMULA] - and [FORMULA] -dependent power spectra to the data. The models we consider are flat cold dark matter (CDM) dominated universes with flat ([FORMULA]) power spectra, thus the results obtained apply only to these models. CMB observations can exclude more than half of the [FORMULA] parameter space explored. The CMB data favor low values of Hubble's constant; [FORMULA]. Low values of [FORMULA] are preferred ([FORMULA]) but the [FORMULA] minimum is shallow and we obtain [FORMULA]. A model with [FORMULA], [FORMULA] and [FORMULA] is permitted by constraints from the CMB data, BBN, cluster baryon fractions and the shape parameter [FORMULA] derived from the mass density power spectra of galaxies and clusters.

For flat- [FORMULA] models, the CMB data, combined with BBN constraints exclude most of the [FORMULA] plane. Models with [FORMULA], [FORMULA] with [FORMULA] are fully consistent with the CMB data but are excluded by the strict new [FORMULA] limits from supernovae (Perlmutter et al. 1997). A combination of CMB data goodness-of-fit statistics, BBN and supernovae constraints in the [FORMULA] plane, limits Hubble's constant to the interval [FORMULA].

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

Send offprint requests to: Charley Lineweaver, charley@cdsxb6.u-strasbg.fr

© European Southern Observatory (ESO) 1997

Online publication: June 5, 1998