2021MNRAS.506.4593Y

We study a simple model describing thermal radiation spectra from magnetized neutron stars. The model assumes that a star is nearly spherical and isothermal inside and possesses dipole magnetic fields (B <= 10¹⁴ G) near the surface, which make the surface temperature distribution non-uniform. We assume further that any surface element emits a blackbody (BB) spectrum with a local effective temperature. We show that such thermal spectra (including phase-resolved) are accurately approximated by simple equivalent two-BB (2BB) models. We introduce and study phase-space maps of 2BB parameters and show that these maps can be useful for interpreting neutron star observations, in which 2BB spectral fits have been done.