New Coordinates for de Sitter Space and de Sitter Radiation

TL;DR

The paper introduces a new coordinate system for de Sitter space with advantageous properties, enabling simplified calculations of horizon tunneling rates and revealing that radiation temperature decreases when self-gravitation is considered.

Contribution

A novel coordinate system for de Sitter space with smooth horizons and flat slices, facilitating new insights into horizon tunneling and radiation temperature.

Findings

Coordinate system with smooth horizon and flat slices

Tunneling rate is approximately thermal without self-gravitation

Effective temperature decreases during radiation emission

Abstract

We introduce a simple coordinate system covering half of de Sitter space. The new coordinates have several attractive properties: the time direction is a Killing vector, the metric is smooth at the horizon, and constant-time slices are just flat Euclidean space. We demonstrate the usefulness of the coordinates by calculating the rate at which particles tunnel across the horizon. When self-gravitation is taken into account, the resulting tunneling rate is only approximately thermal. The effective temperature decreases through the emission of radiation.