Modeling of Thermal Emission from ULX Pulsar Swift J0243.6+6124 with General Relativistic Radiation MHD Simulations

We perform general relativistic radiation magnetohydrodynamics (MHD) simulations of super-Eddington accretion flows around a neutron star with dipole magnetic field for modeling the galactic ultra-luminous X-ray source (ULX) exhibiting pulsations, Swift J0243.6+6124. Our show columns near poles, disk outside magnetosphere, and outflows from disk. It is revealed that effectively optically thick outflows, consistent observed thermal emission at $\sim10^7$ K, are generated if mass rate much higher than Eddington $\dot{M}_{\rm Edd}$ magnetospheric radius smaller spherization radius. In order to explain blackbody ($\sim 100-500$ km) without contradicting reported spin period ($9.8~{\rm s}$) spin-up ($\dot{P}=-2.22\times10^{-8}~{\rm s~s^{-1}}$), $(200-1200)\dot{M}_{\rm required. Since was detected in two observations $\dot{P}$ $-2.22\times10^{-8}~{\rm s~s^{-1}}$ $-1.75\times10^{-8}~{\rm but not another $\dot{P}=-6.8 \times10^{-9}~{\rm s~s^{-1}}$, surface strength J0243.6+6124 estimated be between $3\times10^{11}~{\rm G}$ $4\times10^{12}~{\rm G}$. From this restricted range strength, would $(200-500)\dot{M}_{\rm when appears $(60-100)\dot{M}_{\rm it detected. results support hypothesis phase 2017-2018 giant outburst powered by highly onto magnetized star.