Spontaneous particle creation by oscillating compact stars

TL;DR

This paper investigates how radial oscillations of compact stars can spontaneously create particles from the quantum vacuum, revealing a resonance pattern in the particle spectrum through non-perturbative numerical analysis.

Contribution

It introduces a non-perturbative numerical approach to study particle creation by oscillating compact stars, highlighting a resonance structure in the resulting particle spectrum.

Findings

Confirmed particle creation occurs in oscillating compact stars

Identified a resonance structure in the particle spectrum

Provided full spectrum and particle number in strong-field regime

Abstract

Quantum field theory predicts that dynamical curved spacetimes can spontaneously excite particle pairs from the quantum vacuum, a phenomenon extensively studied in expanding universes and in scenarios involving gravitational collapse. In this article, we explore particle creation driven by radial oscillations of 3+1-dimensional spherically symmetric compact objects, such as neutron stars, using a massless, minimally coupled scalar field as a reference model. We employ a toy model to describe the oscillatory dynamics and its coupling to the field modes, focusing on the resulting effects in the exterior spacetime of the star. The Bogoliubov coefficients relating the in and out vacua are computed non-perturbatively using high-precision numerical methods, without relying on weak-field, small-amplitude or small-velocity expansions. This allows us to determine the full particle spectrum and the total particle number in the strong-field and fully relativistic regime. Our analysis confirms the existence of particle creation in this setting and, crucially, reveals a distinct resonance structure in the spectrum.