Spectra of accreting X-ray pulsars

Using recent improved results on the frequency and polarization dependent opacities in a strong magnetic field, the physics of the lower accretion column on a magnetic neutron star is examined to determine the spectrum radiated at infinity. It is argued that photon convection by the fast infalling material (free fall velocities of approximately c/2) should substantially modify the spectrum radiated through the accretion column due to the frequency dependence of the opacity