Multiple Inflationary Stages with Varying Equation of State

Abstract

We consider a model of inflation consisting a single fluid with a time-dependent equation of state. In this phenomenological picture, two periods of inflation are separated by an intermediate non-inflationary stage which can be either a radiation dominated, matter dominated or kinetic energy dominated universe, respectively, with the equation of state $w=1/3$, 0 or 1. We consider the toy model in which the change in $w$ happens instantaneously. Depending on whether the mode of interest leaves the horizon before or after or between the phase transitions, the curvature power spectrum can have non-trivial sinusoidal modulations. This can have interesting observational implications for CMB anisotropies and for primordial black-hole formation.

minor revision, published version

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• Toward inflation models compatible with the no-boundary proposal
• Analytical investigation of pre-inflationary effects in the primordial power spectrum: From General Relativity to hybrid Loop Quantum Cosmology
• What initial condition of inflation would suppress the large-scale CMB spectrum?
• Jump in fluid properties of inflationary universe to reconcile scalar and tensor spectra
• A Universal Bound on Excitations of Heavy Fields during Inflation
• Choice of vacuum state and the relation between inflationary and Planck scales
• Enhanced spectrum of primordial perturbations, galaxy formation and small scale structure
• Minimal-supersymmetric extended inflation field in Horava-Lifshitz gravity
• Cosmology from a running vacuum model driven by a scalar field
• Primordial perturbations in kinetically dominated regimes of general relativity and hybrid quantum cosmology
• Analytic Approximations for the Primordial Power Spectrum with Israel Junction Conditions