Estimation of temperature of cosmological apparent horizons: a new approach

TL;DR

This paper introduces a novel method to estimate the temperature of cosmological apparent horizons in FLRW models by analyzing radiation using Kodama vectors in a dynamic spacetime setting.

Contribution

It develops a new approach to determine horizon temperature in dynamic cosmological models using Kodama vectors and mode analysis.

Findings

Successfully constructs positive frequency modes across the horizon.

Provides a new way to estimate horizon temperature in non-static spacetimes.

Enhances understanding of horizon thermodynamics in cosmology.

Abstract

We consider radiation from cosmological apparent horizon in Friedmann-Lemaitre-Robertson-Walker(FLRW) model in a double-null coordinate setting. As the spacetime is dynamic, there is no timelike Killing vector, instead we have Kodama vector which acts as dynamical time. We construct the positive frequency modes of the Kodama vector across the horizon. The conditional probability that a signal reaches the central observer when it is crossing from the outside gives the temperature associated with the horizon.