$f$-mode oscillations of protoneutron stars

TL;DR

This paper studies nonradial $f$-mode oscillations of protoneutron stars using general relativity and various equations of state, confirming universal relations and discussing observational prospects.

Contribution

It demonstrates the validity of universal relations for $f$-mode characteristics in isentropic protoneutron stars across different equations of state.

Findings

Confirmed universal relations for $f$-mode frequencies and damping times.

Provided $f$-mode frequency and gravitational-wave amplitude predictions.

Validated universal relations during protoneutron star evolution.

Abstract

We investigate nonradial $f$-mode oscillations of protoneutron stars in full general relativity, employing equations of state described by the Brueckner-Hartree-Fock theory or the relativistic mean field model, while assuming isentropy and fixed lepton fractions for the internal structure. The validity of various universal relations for cold neutron stars involving $f$-mode characteristics and macroscopic properties of the star is confirmed for those isentropic protoneutron stars. Prospects of observations are also discussed. According to simulation results, we then model details of the thermal and trapping profiles in a PNS with the canonical mass. The corresponding $f$-mode frequencies and gravitational-wave strain amplitudes are presented. The validity of the universal relations during the evolution to the formation of a cold neutron star is confirmed.