  We perform a global 2.5D general-relativistic radiation magnetohydrodynamic
simulation of super-critical accretion onto a neutron star with a $2\times
10^{10}$ G dipolar magnetic field, as a model of a neutron-star-powered
ultraluminous X-ray source (ULX). We compute a lower limit on the total
luminosity of $\sim 2.5\,L_\mathrm{Edd}$, and find the radiation to be highly
beamed by the accretion disk outflows. The apparent isotropic luminosity, which
is a function of the viewing angle, reaches a maximum above
$100\,L_\mathrm{Edd}$, consistent with the luminosities observed in ULXs.

High Energy Astrophysical Phenomena