Cosmological singularities and 2-dimensional dilaton gravity

TL;DR

This paper investigates cosmological singularities in 2D dilaton gravity theories derived from higher dimensions, revealing universal behaviors near singularities and classifying various cosmological backgrounds, including known and new solutions.

Contribution

It uncovers universal near-singularity behavior in 2D dilaton gravity and classifies a broad range of cosmological solutions, extending previous knowledge with new classes.

Findings

Universal interrelations between exponents near singularities

Recovery of known solutions like AdS Kasner singularity

Discovery of new cosmological background classes

Abstract

We study Big-Bang or -Crunch cosmological singularities in 2-dimensional dilaton-gravity-scalar theories, in general obtained by dimensional reduction of higher dimensional theories. The dilaton potential encodes information about the asymptotic data defining the theories, and encompasses various families such as flat space, $AdS$, conformally $AdS$ as arising from nonconformal branes, and more general nonrelativistic theories. We find a kind of universal near singularity behaviour independent of the dilaton potential, giving universal interrelations between the exponents defining the time behaviour near the cosmological singularity. More detailed analysis using a scaling ansatz enables finding various classes of cosmological backgrounds, recovering known examples such as the $AdS$ Kasner singularity as well finding as new ones. We give some comments on the dual field theory from this point of view.