Instabilities of scalar fields around oscillating stars

TL;DR

This paper investigates how scalar fields behave around oscillating stars, revealing instabilities that could impact theories of dark matter, dark energy, and gravity, with implications for constraining scalar-tensor theories.

Contribution

It introduces the study of scalar field instabilities in dynamic backgrounds like oscillating stars, extending previous static analyses to more realistic astrophysical scenarios.

Findings

Identification of blueshift and parametric instabilities in scalar fields

Potential constraints on scalar-tensor gravity theories

Insights into scalar field behavior in dynamic astrophysical environments

Abstract

The behavior of fundamental fields in strong gravity or nontrivial environments is important for our understanding of nature. This problem has interesting applications in the context of dark matter, of dark energy physics or of quantum field theory. The dynamics of fundamental fields has been studied mainly in static or stationary backgrounds, whereas most of our Universe is dynamic. In this paper we investigate "blueshift" and parametric instabilities of scalar fields in dynamical backgrounds, which can be triggered (for instance) by oscillating stars in scalar-tensor theories of gravity. We discuss possible implications of our results, which include constraints on an otherwise hard-to-access parameter space of scalar-tensor theories.