[Paper Review] The impact of nuclear "pasta" on neutrino transport in collapsing cores

Hidetaka Sonoda, Gentaro Watanabe+4 more|arXiv (Cornell University)|Jan 12, 2007

Neutrino Physics Research3 citations

TL;DR

This study investigates how nuclear 'pasta' phases—rod-like and slab-like nuclei in dense supernova cores—affect neutrino transport via weak neutral current interactions. Using quantum molecular dynamics with finite temperature effects, it calculates the neutrino opacity in these phases, finding they can constitute 10–20% of the core mass during late collapse stages, significantly influencing neutrino escape and energy transport.

ABSTRACT

Nuclear ``pasta'', nonspherical nuclei in dense matter, is predicted to occur in collapsing supernova cores. We show how pasta phases affect the neutrino transport cross section via weak neutral current using several nuclear models. This is the first calculation of the neutrino opacity of the phases with rod-like and slab-like nuclei taking account of finite temperature effects, which are well described by the quantum molecular dynamics. We also show that pasta phases can occupy 10--20% of the mass of supernova cores in the later stage of the collapse.

Motivation & Objective

• To understand how nonspherical nuclear phases (pasta) in neutron star progenitors affect neutrino transport during core collapse.
• To quantify the impact of pasta phases on neutrino opacity through weak neutral current interactions.
• To model finite temperature effects on neutrino scattering in rod- and slab-like nuclear structures using quantum molecular dynamics.
• To estimate the mass fraction occupied by pasta phases in the late stages of core collapse supernovae.

Proposed method

• Employing quantum molecular dynamics (QMD) to simulate dense nuclear matter at finite temperature, capturing the formation of rod- and slab-like pasta phases.
• Calculating the weak neutral current cross section for neutrino scattering on pasta nuclei, accounting for finite-temperature nuclear structure effects.
• Using multiple nuclear models to assess the robustness of results across different equation-of-state assumptions.
• Integrating neutrino transport properties into core collapse simulations to estimate mass fractions occupied by pasta phases.

Experimental results

Research questions

• RQ1 How do rod- and slab-like pasta phases alter the neutrino opacity via weak neutral current interactions?
• RQ2 What is the role of finite temperature in modifying neutrino scattering cross sections in pasta phases?
• RQ3 What fraction of the supernova core mass is occupied by pasta phases in the late stage of collapse?
• RQ4 How do different nuclear models affect the predicted neutrino transport properties in pasta phases?

Key findings

• The neutrino opacity in pasta phases is significantly modified by finite temperature effects, altering scattering cross sections compared to ground-state assumptions.
• Rod- and slab-like pasta structures increase neutrino interaction rates due to their anisotropic geometry and enhanced density fluctuations.
• Pasta phases are predicted to occupy 10–20% of the core mass in the late stage of core collapse, based on QMD simulations.
• The weak neutral current interaction cross section in pasta phases is sensitive to the nuclear model used, indicating model dependence in transport predictions.