Gravitational waves from supernova matter

TL;DR

This study uses 3D magnetohydrodynamical simulations to analyze how initial conditions of supernova progenitors affect gravitational wave signals, highlighting the importance of neutrino transport and deleptonization effects.

Contribution

It provides new insights into the dependence of gravitational wave signals on progenitor rotation and neutrino physics in supernova simulations.

Findings

Non-rotating models emit gravitational waves from convection.

Slowly rotating models show rotational instabilities at low T/|W|.

Deleptonization significantly increases GW signal strength.

Abstract

We have performed a set of 11 three-dimensional magnetohydrodynamical core collapse supernova simulations in order to investigate the dependencies of the gravitational wave signal on the progenitor's initial conditions. We study the effects of the initial central angular velocity and different variants of neutrino transport. Our models are started up from a 15 solar mass progenitor and incorporate an effective general relativistic gravitational potential and a finite temperature nuclear equation of state. Furthermore, the electron flavour neutrino transport is tracked by efficient algorithms for the radiative transfer of massless fermions. We find that non- and slowly rotating models show gravitational wave emission due to prompt- and lepton driven convection that reveals details about the hydrodynamical state of the fluid inside the protoneutron stars. Furthermore we show that protoneutron stars can become dynamically unstable to rotational instabilities at T/|W| values as low as ~2 % at core bounce. We point out that the inclusion of deleptonization during the postbounce phase is very important for the quantitative GW prediction, as it enhances the absolute values of the gravitational wave trains up to a factor of ten with respect to a lepton-conserving treatment.