Modelling the Tayler–Spruit Dynamo in the Global Evolution of Long-lived Hypermassive Neutron Star Remnants

We perform global, general-relativistic neutrino radiation magnetohydrodynamic simulations of a long-lived hypermassive neutron star (HMNS) remnant formed from a binary neutron star (BNS) merger. Notably, this study represents the first implementation of an approximated Tayler-Spruit (TS) dynamo in the simulation of BNS merger framework. Our objective is to investigate angular momentum transport across distinct physical regimes: the high-density interior, where the TS dynamo is expected to operate, and the low-density exterior, where magnetorotational instability (MRI)-driven turbulence dominates. We analyze how the inclusion of the TS dynamo alters the overall system dynamics, the properties of the resulting mass ejecta, and the potential for electromagnetic signals generated by long-lived magnetar remnants.