OBSERVATIONAL TESTS OF ONE-BUBBLE OPEN INFLATIONARY COSMOLOGICAL MODELS

Motivated by recent studies of the one-bubble inflationary scenario, s imple open cold dark matter models are tested for consistency with cos mological observations. The initial perturbation spectrum is derived b y solving for the evolution of fluctuations in an open inflationary st age under the assumptions that a scalar held is in the Bunch-Davies va cuum state and the conformal vacuum state. A likelihood analysis is pe rformed for the cosmic microwave background anisotropies using the two -year COBE Differential Microwave Radiometer (DMR) data. For Ohm(0) le ss than or similar to 0.2, the two models give significantly different results because of the appearance of fluctuations of supercurvature s cale in the model associated with the Bunch-Davies vacuum state. Havin g normalized the perturbation spectrum to fit the COBE data, we recons ider the validity of the open model from the viewpoint of cosmic struc ture formation, Open models may be severely constrained by the COBE li kelihood analysis. In particular, small values of Ohm(0) are ruled out in the Bunch-Davies case: we find that Ohm(0), greater than or equal to 0.34 at 95% confidence for this model.