Atmospheres and radiating surfaces of neutron stars

The early 21st century is witnessing a breakthrough in the study of the thermal radiation of neutron stars. Observations with modern space telescopes have provided a wealth of valuable information, which, when properly interpreted, can elucidate the physics of superdense matter in the interior of these stars. This interpretation is underlain by the theory of formation of the neutron star thermal spectra, which is in turn based on plasma physics and on the understanding of radiative processes in stellar photospheres. In this paper, the current status of the theory is reviewed, with particular emphasis on neutron stars with strong magnetic fields. In addition to the conventional deep (semi-infinite) atmospheres, radiative condensed surfaces of neutron stars and ‘thin’ (finite) atmospheres are considered.