A Linear Response relation for perturbations in compact stars and the classical Einstein-Langevin formalism

TL;DR

This paper develops a linear response framework for perturbations in relativistic stars, linking microscopic fluctuations to macroscopic perturbations, and introduces an Einstein-Langevin formalism for dense matter in compact stars.

Contribution

It presents a novel linear response relation and Einstein-Langevin equation for relativistic star perturbations, emphasizing the role of mesoscopic fluctuations.

Findings

Perturbations can originate from internal mesoscopic fluctuations.

Solutions to the Einstein-Langevin equation are obtained analytically for simple cases.

Framework may advance asteroseismology through first principles modeling.

Abstract

We give a linear response relation for perturbations in relativistic stars and classify them in terms of implicit and induced perturbations. The focus in this article is on the induced perturbations which may arise due to internal sources in dense matter compact objects. Based on the linear response relation, an Einstein Langevin equation is given and its solutions for a simple case are obtained in closed analytical form as a first exercise. Our results show how perturbations in relativistic stars can arise due to a cumulative effect of mesoscopic scale fluctuations in the dense matter fluids, which otherwise seem to be screened off at hydrodynamic scales due to averaging. We discuss the relevance of such a framework and its potential towards building up a theme of research in asteroseismology using a first principles approach.