Princeton University Thunch Talk

A Parameter Survey of Neutron Star Accretion Column Simulations
Abstract: Accretion-powered X-ray pulsars are neutron stars that accrete matter from a companion star in a binary system. The strong magnetic field of the neutron star channels material onto the magnetic poles, which are typically misaligned with the spin axis, producing pulsating X-rays as the star rotates. At sufficiently high accretion rates, radiation pressure supports this magnetically confined flow, forming a column structure near the poles. In this study, we conduct a parameter survey using radiation relativistic MHD simulations to investigate the dynamics of the accretion column as a function of accretion rate, magnetic field strength, and accretion geometry. Our simulations incorporate a comprehensive opacity table that accounts for magnetic electron scattering, magnetic bremsstrahlung, cyclotron resonance, vacuum polarization, and electron-positron pair production. We also explore two distinct accretion geometries: solid and hollow column structures. In this talk, I will discuss the dynamical effects introduced by these factors and highlight results relevant to observations. In our future work, we plan to compute the spectrum and polarization based on our current numerical models to establish a more direct connection with observational data.