| Abstract: Our knowledge of Neutron Star (NS) properties has significantly advanced through X-ray spectro-timing analysis using highly sensitive instruments. However, studying the fundamental properties of NS from these observations requires a complete and robust understanding of the accretion mechanisms. Significant questions remain regarding the location of hot spots on the NS surface, accretion geometry, and magnetic field structure near the magnetic poles of the NS. A phenomenological model, like a power law, with or without a high-energy cutoff, mimics the Comptonized emission from NS. With the advent of modern high-resolution instruments, self-consistent modelling of the NS spectrum is the need of the hour. It is essential to ground such physical models to understand the origins of broadband NS emission. We report the implications of the physical modelling of Galactic ULX Pulsar Swift J0243.6+6124. The seed photon distribution can originate from either blackbody radiation at the bottom of the accretion column or Bremsstrahlung radiation from the NS surface. We utilise broadband data from current instruments with significantly high spectral sensitivity, such as Swift-XRT, NICER, and NuSTAR, to perform self-consistent modelling of the broadband continuum and reflection line features in NS spectra. We discuss the possible origin scenarios of the iron fluorescence emission using a reflection component, which is seeded by a physically consistent illuminator. We report on the phase-resolved broadband spectral analysis of the source and how the emission mechanism varies with the spin rotation of the NS. |
