[Paper Review] Core-Collapse Supernovae: Explosion Dynamics, Neutrinos and Gravitational Waves

Bernhard Mueller, Hans‐Thomas Janka+4 more|arXiv (Cornell University)|Dec 8, 2011

Gamma-ray bursts and supernovae3 references4 citations

TL;DR

This paper presents the first 2D axisymmetric core-collapse supernova simulations including general relativity (GR) in multi-dimensional neutrino hydrodynamics, using the Vertex code with a relativistic ray-by-ray variable Eddington factor method. It demonstrates that GR significantly enhances the gravitational wave signal's peak frequency (to ~900 Hz) and alters neutrino luminosities and shock deformation, particularly in asymmetric $15M_{igodot}$ models, while the effective potential approximation overestimates this effect.

ABSTRACT

The quest for the supernova explosion mechanism has been one of the outstanding challenges in computational astrophysics for several decades. Simulations have now progressed to a stage at which the solution appears close and neutrino and gravitational wave signals from self-consistent explosion models are becoming available. Here we focus one of the recent advances in supernova modeling, the inclusion of general relativity in multi-dimensional neutrino hydrodynamics simulations, and present the latest simulation results for an 11.2 and a 15 solar mass progenitor. We also mention 3D effects as another aspect in supernova physics awaiting further, more thorough investigation.

Motivation & Objective

• To investigate the impact of general relativity on core-collapse supernova explosion dynamics, neutrino emission, and gravitational wave signals.
• To assess the role of GR in enhancing the efficiency of the neutrino-driven explosion mechanism in multi-dimensional simulations.
• To compare GR effects with Newtonian and effective potential approximations in modeling $11.2M_{igodot}$ and $15M_{igodot}$ progenitors.
• To evaluate how GR and improved neutrino microphysics influence shock deformation and asymmetries in the explosion geometry.
• To lay the groundwork for future 3D simulations by quantifying the sensitivity of signals to gravity and neutrino transport.

Proposed method

• Employed the Vertex code with a relativistic generalization of the ray-by-ray variable Eddington factor method for multi-group neutrino transport.
• Conducted 2D axisymmetric simulations of core-collapse supernovae for $11.2M_{igodot}$ and $15M_{igodot}$ progenitors, including full GR hydrodynamics.
• Compared results under three gravity treatments: full GR, Newtonian, and an effective potential approximation.
• Used detailed neutrino opacities including recoil, high-density correlations, and weak magnetism effects to improve microphysical accuracy.
• Computed neutrino luminosities, mean energies, and gravitational wave signals from the time-averaged mass quadrupole moment.
• Analyzed angular anisotropies in neutrino emission and shock deformation to assess asymmetries in explosion dynamics.

Experimental results

Research questions

• RQ1 How do general relativistic effects alter the explosion dynamics and shock evolution in core-collapse supernovae?
• RQ2 What is the impact of GR on neutrino luminosities and mean energies at the gain radius in 2D simulations?
• RQ3 How does GR influence the gravitational wave signal, particularly its peak frequency and amplitude?
• RQ4 To what extent do GR effects modify the asymmetry of the explosion, especially in the $15M_{igodot}$ progenitor?
• RQ5 How do different gravity approximations (full GR vs. effective potential) compare in predicting neutrino and gravitational wave signals?

Key findings

• GR increases the peak frequency of the gravitational wave signal to approximately 900 Hz, compared to 500 Hz in the Newtonian case.
• The effective potential approximation overestimates the peak frequency at ~1100 Hz due to an artificially higher Brunt-Väisälä frequency.
• In the $15M_{igodot}$ model, GR induces strong dipolar shock deformation and asymmetric neutrino emission, with a monotonically rising 'tail' in the gravitational wave signal.
• Neutrino luminosities and mean energies at the gain radius are significantly altered by GR, particularly in the $15M_{igodot}$ case.
• The $11.2M_{igodot}$ model shows a nearly spherical shock in GR, while the $15M_{igodot}$ model exhibits pronounced asphericity.
• The relative difference in neutrino flux between hemispheres reaches up to ~20% in the $15M_{igodot}$ model, indicating strong anisotropic emission driven by GR and hydrodynamical instabilities.