Extended Data Fig. 3: Neutrino viscosity and drag on the magnetorotational instability.

Growth rate of the fastest growing mode of the neutrino viscous/drag magnetorotational instability as a function of the radius of the remnant massive neutron star and the hypothetical value of the z-component of the magnetic field \({B}_{{{{\rm{hyp}}}}}^{z}\). We take the simulation data on the orbital plane at t − t_merger ≈ 10 ms. The purple curve denotes the boundary where \({\tilde{\nu }}_{\nu }\) or \({\tilde{\Gamma }}_{\nu }\approx 1\). Outside the boundary, the growth rate is essentially the same as the ideal magnetorotational instability. The red curve denotes the z-component of the azimuthally averaged magnetic field strength in the simulation. The orange-solid (dashed) curve denotes the three-dimensional data for the z-component on the x = 0 axis in the simulation with Δx_finest = 12.5(200) m.