Title: Thermal and magnetic effects on viscosity in Binary Neutron Star mergers Show Chinese title

Title: 热和磁效应在双中子星合并中的粘度

Abstract: Astrophysical scenarios such as binary neutron star mergers, proto-neutron stars and core-collapse supernovae involve finite temperatures and strong magnetic fields. Previous studies on the effect of magnetic fields on flavor-equilibration processes such as direct Urca relied on the Fermi surface approximation, which is not a reliable approximation in the neutrino-transparent regime of matter in supernovae or neutron star mergers. In a recent study, we went beyond the Fermi surface approximation, performing the full phase space integral to obtain direct Urca rates in background magnetic field. In this work, we extend these calculations to include collisional broadening effects by employing the recently developed nucleon width approximation. We demonstrate the impact of magnetic fields on the flavor-equilibrium condition for two finite-temperature equations of state with different direct Urca thresholds. We also study the impact of magnetic fields on the bulk viscous dissipation of density oscillations relevant in postmerger scenarios. Show Chinese abstract

Abstract: 天体物理情景，如双中子星合并、原中子星和核心坍缩超新星涉及有限温度和强磁场。 先前关于磁场对味平衡过程（如直接Urca过程）影响的研究依赖于费米面近似，在超新星或中子星合并物质的中微子透明区域，这种近似并不可靠。 在最近的一项研究中，我们超越了费米面近似，进行了完整的相空间积分，以在背景磁场中获得直接Urca速率。 在本工作中，我们通过采用最近发展的核子宽度近似，将这些计算扩展以包括碰撞展宽效应。 我们展示了磁场对两种具有不同直接Urca阈值的有限温度状态方程的味平衡条件的影响。 我们还研究了磁场对与合并后情景相关的密度振荡体粘性耗散的影响。