Radial Oscillations of Neutron Stars with Antikaon Condensate

TL;DR

This study investigates how antikaon condensates influence the structure and radial oscillation frequencies of neutron stars, revealing distinct effects on eigenfunctions and pressure perturbations.

Contribution

It introduces a relativistic mean field model with density-dependent couplings to analyze antikaon effects on neutron star oscillations, including phase transition treatment and eigenfunction analysis.

Findings

Antikaon presence alters eigenfunctions of radial modes.

Eigenfunctions for pressure perturbations remain unchanged despite antikaons.

Distinct features in oscillation frequencies due to antikaon condensates.

Abstract

In this article, we study the neutron stars with antikaon condensates and their radial oscillations. We incorporate the antikaons $(K^-,\bar{K}^0)$ within a relativistic mean field theory with density dependent couplings. A transition to the kaon condensed phase is treated as a second order phase transition for different possible antikaon optical potentials. Then, we solve the structure equations of stars and calculate the fundamental and higher order frequencies of their radial pulsations. We study the eigenfunctions of different radial modes for a $2M_\odot$ star with equations of state having different potential depths of antikaons. We also study the large frequency separations for the $2M_\odot$ star. We find distinct features of the appearances of antikaons on the eigenfunctions. The shape of the eigenfunctions corresponding to the radial perturbations is affected due to the appearance of the antikaons, but for the pressure perturbation, the shape remains unchanged.