as tr o - ph / 9 50 81 57 31 A ug 1 99 5 Why Not Consider Closed Universes ?
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چکیده
We consider structure formation and cosmic microwave background (CMB) aniso-tropies in a closed universe, both with and without a cosmological constant. The CMB angular power spectrum and the matter transfer function are presented, along with a discussion of their relative normalization. This represents the rst full numerical evolution of density perturbations and anisotropies in a spherical geometry. We extend the likelihood function vs. from the COBE 2-year data to 1. For large the presence of a very steep rise in the spectrum towards lowàllows us to put an upper limit of 1:5 (95%CL) for primordial spectra with n 1. This compares favorably with existing limits on. We show that there are a range of closed models which are consistent with observational constraints while being even older than the currently popular at models with a cosmological constant. Future constraints from degree scale CMB data may soon probe this region of parameter space. A derivation of the perturbed Einstein, uid and Boltzmann equations for open and closed geometries is presented in an appendix.
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تاریخ انتشار 1995