Speaker
Description
In the extreme environments of binary neutron star (BNS) mergers, temperatures (T $\sim 1−50$ MeV) and magnetic fields (B $\sim 10^{15}−10^{17}$ G) reach regimes 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 (NWA) 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 ($E_{\nu}\sim 3T$). This enhanced opacity lowers 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.