Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Why Not Consider Closed Universes?   We consider structure formation and CMB anisotropies 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 first full numerical
evolution of density perturbations and anisotropies in a spherical geometry. We
extend the likelihood function vs. Omega from the COBE 2-year data to Omega>=1.
For large Omega the presence of a very steep rise in the spectrum towards low
ell allows us to put an upper limit of Omega<=1.5 (95%CL) for primordial
spectra with n<=1. This compares favorably with existing limits on Omega. We
show that there are a range of closed models which are consistent with
observational constraints while being even older than the currently popular
flat 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, fluid and Boltzmann equations for open and closed
geometries is presented in an appendix.

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The categories of this paper are: math-ph
35
The categories of this paper are: mtrl-th
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The categories of this paper are: atom-ph
0
The categories of this paper are: hep-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: cmp-lg
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The categories of this paper are: hep-lat
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The categories of this paper are: alg-geom
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The categories of this paper are: plasm-ph
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The categories of this paper are: eess
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The categories of this paper are: quant-ph
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The categories of this paper are: adap-org
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The categories of this paper are: bayes-an
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The categories of this paper are: patt-sol
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The categories of this paper are: q-fin
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The categories of this paper are: math