Speaker
Description
In the extreme environments of binary neutron star (BNS) mergers, the neutron star matter reaches temperatures (T ~ $ 1-50$ MeV) and magnetic fields (B ~ $10^{15} - 10^{17}$ G) where neutrino transport govern the macroscopic thermodynamic and chemical evolution. Standard merger simulations frequently rely on zero-field neutrino opacities, potentially missing critical transport physics in highly magnetized neutron star cores. We present an exact framework for computing charged-current Urca emissivity and neutrino opacity at finite temperature and magnetic field. We use the Nucleon Width Approximation framework to account for the collisional broadening effects dominant in the high-density core. Our calculations demonstrate that extreme magnetic fields significantly enhance charged-current neutrino opacity, effectively reducing the mean free path for thermal neutrinos ($E_{\nu} \sim 3 T $). This enhanced opacity will lower the energy threshold for neutrino trapping, forcing the bulk neutrino gas into a degenerate thermal distribution earlier, and at lower densities than predicted by unmagnetized models.