Constraining Pulsar Radiative Geometry via Multiwavelength Modeling

The center of the thermal X-ray emission, which corresponds to the center of the plasma flow within the polar cap, can be constrained by modeling the thermal X-ray pulse profile, while the rotating-vector model (RVM) fitting is widely used to yield the inclination angle of the focus of polarization orientations of the radio coherent emission. Thus, we propose that the consistency between these two measurements would imply that the polarization orientation is focused at the plasma flow center. Conversely, the discrepancy would suggest that these two centers do not necessarily coincide. One possibility is that as the emission propagates, the evolution of wave modes during wave propagation in the magnetosphere depends strongly on magnetic field orientations. Thus, the focus of the polarization finally overlaps with the center of the magnetic field rather than the plasma flow center. If this happens, the discrepancy can range from one to several degrees. In this paper we estimate the uncertainties of these two measurements in the most ideal situation. We find that the uncertainties of these two measurements can be reduced to less than 1 ∘ to distinguish the discrepancy between the two centers.