Open Inflation Model Research Articles

Complete power spectrum for an induced gravity open inflation model

We study the phenomenological constraints on a recently proposed model of open inflation in the context of induced gravity. The main interest of this model is the relatively small number of parameters, which may be constrained by many different types of observation. We evaluate the complete spectrum of density perturbations, which contains continuum sub-curvature modes, a discrete super curvature mode, and a mode associated with fluctuations in the bubble wall. From these, we compute the angular power spectrum of temperature fluctuations in the microwave background, and derive bounds on the parameters of the model so that the predicted spectrum is compatible with the observed anisotropy of the microwave background and with large-scale structure observations. We analyze the matter era and the approach of the model to general relativity. The model passes all existing constraints.

Observational Constraints on Open Inflation Models.

We discuss observational constraints on models of open inflation. Current data from large-scale structure and the cosmic microwave background prefer models with blue spectra and/or Omega_0 >= 0.3--0.5. Models with minimal anisotropy at large angles are strongly preferred.

Can the simplest two-field model of open inflation survive?

We investigate the quantum fluctuations of an inflaton field in a two-field model of one-bubble open inflation. One of the inflatons is assumed to be responsible for the first false vacuum stage of inflation and the other is assumed to be responsible for the second slow-roll stage of inflation. The mass of the second inflaton is assumed to be negligible throughout the whole era of inflation. We find the super-curvature fluctuations are enhanced by the factor given by the ratio of the Hubble constants at false vacuum and true vacuum. This gives a strong constraint on a class of open inflation models. In particular, this implies the simplest two-field model proposed by Linde and Mezhlumian is in trouble.

Quantum fluctuations and CMB anisotropies in one-bubble open inflation models

We first develop a method to calculate a complete set of mode functions that describe the quantum fluctuations generated in one-bubble open inflation models. We consider two classes of models. One is a single scalar field model proposed by Bucher, Goldhaber, and Turok and by us as an example of the open inflation scenario, and the other is a two-field model such as the supernatural inflation proposed by Linde and Mezhlumian. In both cases we assume the difference in the vacuum energy density between inside and outside the bubble is negligible. There are two kinds of mode functions. One kind has the usual continuous spectrum and the other has a discrete spectrum with characteristic wavelengths exceeding the spatial curvature scale. The latter can be further divided into two classes in terms of its origin. One is called the de Sitter supercurvature mode, which arises due to the global spacetime structure of de Sitter space, and the other is due to fluctuations of the bubble wall. We calculate the spectrum of quantum fluctuations in these models and evaluate the resulting large angular scale CMB anisotropies. We find there are ranges of model parameters that are consistent with observed CMB anisotropies.

Metric perturbations from quantum tunneling in open inflation.

We study the effect that quantum fluctuations produced during the nucleation of a single-bubble open inflationary universe have on the amplitude of temperature anisotropies in the microwave background. We compute the instanton action for the quantum tunneling between the false and true vacua in open inflation models and show that the amplitude of quantum fluctuations of the bubble wall is very sensitive to the gravitational effects of the true vacuum. We study the spectrum of quantum fluctuations of the bubble wall and confirm that there is only an inhomogeneous (${k}^{2}=\ensuremath{-}3$) discrete mode associated with transverse traceless fluctuations of the bubble wall. This supercurvature mode could, in principle, distort the anisotropy of the microwave background. We compute the amplitude of the gauge-invariant metric perturbations induced by the bubble wall fluctuations on a comoving hypersurface, and calculate the induced amplitude of temperature fluctuations in the microwave background, for arbitrary values of ${\ensuremath{\Omega}}_{0}$. We find that in the limit ${\ensuremath{\Omega}}_{0}\ensuremath{\simeq}1$, the quadrupole dominates the angular power spectrum, such as in the usual Grishchuk-Zel'dovich effect. The resulting bounds on the amplitude of quantum fluctuations of the bubble wall from the absence of such an effect in the observed microwave background anisotropies are quite strong. We also study the contribution from a discrete long wavelength supercurvature mode (${k}^{2}\ensuremath{\simeq}\frac{2{m}^{2}}{3{H}^{2}}$) that appears in the spectrum of open de Sitter vacuum fluctuations. We constrain the parameters of the models of open inflation so that these modes do not distort the observed temperature anisotropy.

COBE DMR-normalized open inflation cold dark matter cosmogony

view Abstract Citations (66) References (32) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS COBE DMR--normalized Open Inflation, Cold Dark Matter Cosmology Gorski, Krzysztof M. ; Ratra, Bharat ; Sugiyama, Naoshi ; Banday, Anthony J. Abstract Fourier analysis on a cut sky of the two-year COBE DMR 53 and 90 GHz sky maps (in galactic coordinates) is used to determine the normalisation of an open inflation model based on the cold dark matter scenario. The normalised model is compared to measures of large-scale structure in the universe. Although the DMR data alone does not provide sufficient discriminative power to prefer a particular value of the mass density parameter, the open model appears to be reasonably consistent with observations when Omega_0 ~ 0.3 - 0.4 and merits further study. Publication: The Astrophysical Journal Pub Date: May 1995 DOI: 10.1086/187861 arXiv: arXiv:astro-ph/9502034 Bibcode: 1995ApJ...444L..65G Keywords: Background Radiation; Cosmology; Dark Matter; Density Distribution; Galactic Evolution; Universe; Anisotropy; Mass Distribution; Mathematical Models; Maximum Likelihood Estimates; Microwaves; Power Spectra; Astrophysics; COSMOLOGY: COSMIC MICROWAVE BACKGROUND; COSMOLOGY: OBSERVATIONS; COSMOLOGY: LARGE-SCALE STRUCTURE OF UNIVERSE; GALAXIES: FORMATION; Astrophysics E-Print: uuencoded file containing 6 postscript files (11 pgs text, 4 figures, 1 table) full text sources arXiv | ADS |