An Intrinsic Degeneracy in a Simplified Semi-Analytic Two-Spot Model for Thermal X-Ray Pulse-Profiles
This study investigated an intrinsic degeneracy in simplified two-spot models used to fit thermal X-ray pulse profiles of neutron stars. Even when accounting for Doppler effects and instrument response, the model yields two distinct high-likelihood solutions. This suggests that having prior knowledge of geometric parameters is essential to resolve these ambiguities, explaining multi-modal results seen in previous studies.