Polarization of Thermal X‐Rays from Isolated Neutron Stars

Since the opacity of a magnetized plasma depends on polarization ofradiation, the radiation emergent from atmospheres of neutron stars with strongmagnetic fields is expected to be strongly polarized. The degree of linearpolarization, typically ~10-30%, depends on photon energy, effectivetemperature and magnetic field. The spectrum of polarization is more sensitiveto the magnetic field than the spectrum of intensity. Both the degree ofpolarization and the position angle vary with the neutron star rotation periodso that the shape of polarization pulse profiles depends on the orientation ofthe rotational and magnetic axes. Moreover, as the polarization issubstantially modified by the general relativistic effects, observations ofpolarization of X-ray radiation from isolated neutron stars provide a newmethod for evaluating the mass-to-radius ratio of these objects, which isparticularly important for elucidating the properties of the superdense matterin the neutron star interiors.Comment: 7 figures, to be published in Ap