Dynamical effects of magnetic opacity in neutron star accretion columns

ABSTRACT We present relativistic radiation magnetohydrodynamic simulations of supercritical neutron star accretion columns in Cartesian geometry, including temperature-dependent polarization-averaged Rosseland mean opacities accounting for classical electron scattering a magnetic field. Just as our previous pure Thomson simulations, vertical oscillations the shock and horizontally propagating entropy waves (photon bubbles) are all simulations. However, at high fields ≳1012 G, produce significant differences overall structure dynamics column. At fixed rate, increasing field strength results shorter column, despite fact that opacity within column is larger. Moreover, oscillation amplitude reduced. Increasing rate restores height new, slower instability takes place these strengths because they regime where increases with temperature. This causes both average to substantially increase on time-scale ∼10 ms. provide physical explanations results, discuss their implications observed properties columns, mixed fan-beam/pencil-beam emission patterns caused by oscillations.