Constraints on open universe models from quadruple anisotropy of the cosmic microwave background

The quadrupole anisotropy of the cosmic microwave background expected in a variety of open universe models is evaluated by taking full account of contributions from both the generalized Sachs-Wolfe effect and intrinsic photon fluctuations at decoupling. Comparing the results with the observed upper limit of the quadrupole anisotropy, constraints on open universe models are derived. It is concluded that, even if the most conservative attitude is adopted, both hot and cold dark matter models with h = 0.5, Omega(0) not greater than 0.2 and all pure baryonic models with Omega(0) not greater than 0.2 are excluded if the initial density spectrum has the power-law index n not greater than 1, while both hot and cold dark matter models with h = 1.0, Omega(0) not greater than 0.2, and n not greater than 1 are marginally consistent with the observed upper limit of the quadrupole if one allows possible ambiguities in the normalization of the perturbation amplitudes. 29 refs