Particle Creation Near the Chronology Horizon

TL;DR

This paper analyzes particle creation in a 2D curved spacetime model with a parameter that determines the formation of a chronology horizon, finding that particle production remains finite during horizon formation.

Contribution

It provides the first detailed calculation of scalar particle spectrum near the chronology horizon in a 2D model, showing finiteness of particle creation.

Findings

Particle spectrum is obtained for the model with $ ext{aout}<1$.

Number of particles created remains finite at the horizon formation.

Spectrum approaches a finite limit as $ ext{aout} o 1$.

Abstract

We investigate the phenomenon of particle creation of the massless scalar field in the model of spacetime in which, depending on the model's parameter $\aout$, the chronology horizon could be formed. The model represents a two-dimensional curved spacetime with the topology $R^1 \times S^1$ which is asymptotically flat in the past and in the future. The spacetime is globally hyperbolic and has no causal pathologies if $\aout<1$, and closed timelike curves appear in the spacetime if $\aout\ge 1$. We obtain the spectrum of created particles in the case $\aout<1$. In the limit $\aout \to 1$ this spectrum gives the number of particles created into mode $n$ near the chronology horizon. The main result we have obtained is that the number of scalar particles created into each mode as well as the full number of particles remain finite at the moment of forming of the chronology horizon.