Deflationary Models Driven by Matter Creation

TL;DR

This paper proposes a nonsingular deflationary cosmology driven by matter creation, eliminating the need for a preinflationary stage and solving key cosmological problems without supercooling or reheating.

Contribution

It introduces a novel deflationary model based on matter creation that avoids supercooling and reheating, providing a continuous evolution from de Sitter space to a standard universe.

Findings

Solves horizon and flatness problems without supercooling.

Predicts present-day radiation temperature consistent with observations.

Shows the age problem is resolved in the model.

Abstract

A nonsingular deflationary cosmology driven by adiabatic matter creation is proposed. In this scenario there is no preinflationary stage as happens in conventional inflationary models. Deflation starts from a de Sitter spacetime characterized by an arbitrary time scale $H_{I}^{-1}$, which also pins down an initial value for the temperature of the universe. The model evolves continuously towards a slightly modified Friedman-Robertson-Walker universe. The horizon and other well known problems of the standard model are then solved but, unlike in microscopic models of inflation, there is no supercooling and subsequent reheating. Entropy generation is concomitant with deflation and if $H_{I}^{-1}$ is of the order of the Planck time, the present day value of the radiation temperature is deduced. It is also shown that the ``age problem'' does not exist here. In particular, the theoretically favored FRW flat model is old enough to agree with the observations even given the high values of $H_{o}$ suggested by recent measurements.