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Magnetized hypermassive neutron stars (HMNSs) have been proposed as a way forneutron star (NS) mergers to produce high electron fraction, high velocityejecta, as required by kilonova models to explain the observed light curve ofGW170817. The HMNS drives outflows through neutrino energy deposition andmechanical oscillations, and raises the electron fraction of outflows throughneutrino interactions before collapsing to a black hole (BH). Here we perform3D numerical simulations of HMNS-torus systems in ideal magnetohydrodynamics,using a leakage/absorption scheme for neutrino transport, the nuclear APRequation of state, and Newtonian self-gravity, with a pseudo-Newtonianpotential added after BH formation. Due to the uncertainty in the HMNS collapsetime, we choose two different parameterized times to induce collapse. We alsoexplore two initial magnetic field geometries in the torus, and evolve thesystems until the outflows diminish significantly ($\sim 1 - 2$ $\mathrm{s}$).We find bluer, faster outflows as compared to equivalent BH-torus systems,producing $M\sim 10^{-3} M_\odot$ of ejecta with $Y_e \geq 0.25$ and $v \geq0.25c$ by the simulation end. Approximately half the outflows are launched indisk winds at times $t\lesssim 500$ $\mathrm{ms}$, with a broad distribution ofelectron fractions and velocities, depending on the initial condition. Theremaining outflows are thermally-driven, characterized by lower velocities andelectron fractions. Nucleosynthesis with tracer particles shows patternsresembling solar abundances in all models. Although outflows from oursimulations do not match those inferred from two-component modelling of theGW170817 kilonova, self-consistent multidimensional detailed kilonova modelsare required to determine if our outflows can power the blue kilonova.

Secular Outflows from 3D-MHD Hypermassive Neutron Star Accretion Disk Systems