Paul J. Steinhardt

Cosmological imprint of an energy component with general equation of state

We examine the possibility that a significant component of the energy density of the Universe has an equation of state different from that of matter, radiation, or cosmological constant ({Lambda} ). An example is a cosmic scalar field evolving in a potential, but our treatment is more general. Including this component alters cosmic evolution in a way that fits current observations well. Unlike {Lambda} , it evolves dynamically and develops fluctuations, leaving a distinctive imprint on the microwave background anisotropy and mass power spectrum. {copyright} {ital 1998} {ital The American Physical Society}

Cluster Abundance Constraints for Cosmological Models with a Time-varying, Spatially Inhomogeneous Energy Component with Negative Pressure

The abundance of rich clusters is a strong constraint on the mass power spectrum. The current constraint can be expressed in the form ? -->8 ?

The physics of quasicrystals

{γ}m

Challenges for superstring cosmology

-->=0.5?0.1, where ?8 is the rms mass fluctuation on 8 h-1 Mpc scales, ?m is the ratio of matter density to the critical density, and ? is model dependent. In this paper, we determine a general expression for ? that applies to any models with a mixture of cold dark matter plus cosmological constant or quintessence (a time-evolving, spatially inhomogeneous component with negative pressure) including dependence on the spectral index n, the Hubble constant h, and the equation of state of the quintessence component w. The cluster constraint is combined with COBE measurements to identify a range of best-fitting models. The constraint from the evolution of rich clusters is also discussed.The abundance of rich clusters is a strong constraint on the mass power spectrum. The current constraint can be expressed in the form

Prescription for Successful Extended Inflation

\sigma_8 \Omega_m^{\gamma} = 0.5 \pm 0.1

Resolving the cosmological missing energy problem

where

Bubble percolation in extended inflationary models

\sigma_8

Polarization of the microwave background due to primordial gravitational waves

is the

Imprint of gravitational waves in models dominated by a dynamical cosmic scalar field

rms

Bubble nucleation and the Coleman-Weinberg model

mass fluctuation on 8