GRMHD simulations of neutrino-cooled accretion onto proto-magnetars

We set up 2D GRMHD simulations of accretion onto black holes and proto-magnetars with a focus on studying the differences between neutrino-cooled outflows generated by each central compact object. We show that neutron stars can generate highly neutron-rich outflows when they are in the 'propeller' regime (that is when the corotation radius is inside the closed magnetosphere of the neutron star) compared to the black hole case. The neutron-rich outflows can have a significant impact on r-process nucleosynthesis. We also show that accretion onto neutron stars opens up the closed field lines, and significantly enhances the jet power compared to an isolated neutron star. We show that accretion specifically induces variability in jet power, which is otherwise absent in an isolated neutron star, making neutron stars a strong contender to being central engines for GRBs.