Nonthermal acceleration radiation of atoms near a black hole in presence of dark energy

TL;DR

This paper explores how dark energy influences atom-field interactions near a black hole, revealing enhanced and oscillatory nonthermal radiation spectra affected by the cosmological constant.

Contribution

It introduces a detailed analysis of acceleration radiation near a black hole with dark energy, showing modifications to radiation spectra and thermality due to the cosmological constant.

Findings

Radiation emission is enhanced by dark energy.

Oscillatory nonthermal spectra depend on black hole mass and atomic frequency.

Dark energy influences the origin and nature of emitted radiation.

Abstract

We investigate how dark energy affects atom-field interaction. To this end, we consider acceleration radiation of a freely falling atom close to a Schwarzschild black hole (BH) in the presence of dark energy characterized by a positive cosmological constant $\Lambda$. The resulting spacetime is endowed with a BH and a cosmological (or de Sitter) horizon. Our consideration is a \textit{nonextremal} $(1+1)$-dimensional geometry with horizons far apart, giving rise to a flat Minkowski-like region in between the two horizons. Assuming a scalar ($\text{spin}-0$) field in a Boulware-like vacuum state, and by using a basic quantum optics approach, we numerically achieve excitation probabilities for the atom to detect a photon as it falls toward the BH horizon. It turns out that the nature of the emitted radiation deeply drives its origin from the magnitude of $\Lambda$. In particular, radiation emission is enhanced due to dilation of the BH horizon by dark energy. Also, we report an oscillatory nonthermal spectrum in the presence of $\Lambda$, and these oscillations, in a varying degree, also depend on BH mass and atomic excitation frequency. We conjecture that such a hoedown may be a natural consequence of a constrained motion due to the bifurcate Killing horizon of the given spacetime. The situation is akin to the Parikh-Wilzcek tunneling approach to Hawking radiation where the presence of extra contributions to the Boltzmann factor deforms the thermality of flux. It apparently hints at field satisfying a modified energy-momentum dispersion relation within classical regime of general relativity arising as an effective low energy consequence of an underlying quantum gravity theory. Our findings may signal new ways of conceiving the subtleties surrounding the physics of dark energy.