X-ray bounds on the r-mode amplitude in millisecond pulsars

TL;DR

This paper uses X-ray observations of millisecond pulsars to set stringent limits on r-mode oscillation amplitudes, providing insights into their internal composition and thermal properties.

Contribution

It introduces a method to constrain r-mode amplitudes in millisecond pulsars using X-ray data, improving previous bounds significantly.

Findings

r-mode amplitude bounds as low as 10^{-8}

X-ray data effectively constrains internal star properties

Implications for neutron star composition models

Abstract

r-mode astroseismology provides a unique way to study the internal composition of compact stars. Due to their precise timing, recycled millisecond radio pulsars present a particularly promising class of sources. Although their thermal properties are still poorly constrained, X-ray data is very useful for astroseismology since r-modes could strongly heat a star. Using known and new upper bounds on the temperatures and luminosities of several non-accreting millisecond radio pulsars we derive bounds on the r-mode amplitude as low as $\alpha\lesssim10^{-8}$ and discuss the impact on scenarios for their internal composition.