Seminar:Are multipolar magnetic fields necessary to model the X-ray emission observed with NICER?

Abstract: Several important properties of rotation-powered millisecond pulsars, such as their mass-radius ratio, equation of state and magnetic field topology, can be inferred from precise observations and modelling of their X-ray light curves. In this talk, I will present a recent approach that goes all the way from numerically solving the surrounding magnetosphere up to the ray tracing of the emitted photons and the final computation of their light curves and spectra. Our modelled X-ray signals are then compared against a set of very accurate NICER observations of four target pulsars, finding very good simultaneous fits for their light curves and spectral distributions. Our results assume simple centered dipolar magnetic fields, in contrast to the strong higher-multipole moments and/or off-centred dipolar components that have been typically inferred from these X-rays light curves.