David H. Lyth

Open cold dark matter models

Motivated by recent developments in inflationary cosmology indicating the possibility of obtaining genuinely open universes in some models, we compare the predictions of cold dark matter (CDM) models in open universes with a variety of observational information. The spectrum of the primordial curvature perturbation is taken to be scale invariant (spectral index

Cosmological Inflation and Large-Scale Structure: Frontmatter

n=1

Cosmological Inflation and Large-Scale Structure: Contents

), corresponding to a flat inflationary potential. We allow arbitrary variation of the density parameter

The Spectral slope in the cold dark matter cosmogony

Omega_0

Cosmological Inflation and Large-Scale Structure: INFLATION

and the Hubble parameter

The Primordial Density Perturbation: Internal symmetry

h

Constants and parameters

, and take full account of the baryon content assuming standard nucleosynthesis. We normalize the power spectrum using the recent analysis of the two year {it COBE} DMR data by G{o}rski et al. We then consider a variety of observations, namely the galaxy correlation function, bulk flows, the abundance of galaxy clusters and the abundance of damped Lyman alpha systems. For the last two of these, we provide a new treatment appropriate to open universes. We find that, if one allows an arbitrary

Thermal equilibrium and the origin of baryon number

h

Multi-field dynamics

, then a good fit is available for any

The Primordial Density Perturbation: Slow-roll inflation and observation

Omega_0