Polarization Modes in a Strongly Magnetized Hydrogen Gas
Abstract
Propagation of highfrequency radiation in an anisotropic medium can be described in terms of two normal modes with different polarizations and different absorption coefficients. We investigate the properties of the normal modes in a strongly magnetized hydrogen gas for conditions expected in atmospheres of isolated neutron stars. We use the KramersKronig relations to obtain the polarizability tensor for the strongly magnetized hydrogen. We derive and compute the polarizations and absorption coefficients of the normal modes from the polarizability tensor using both analytical approximations and numerical calculations. We find that the spectral features and anisotropy associated with the bound bound and boundfree transitions in the magnetized hydrogen are manifested in the polarization characteristics, which affect substantially the spectral and angular dependences of the absorption coefficients of the normal modes and the transfer of radiation in neutron star atmospheres. There exist at least two critical frequencies at which, for any direction of propagation, either the normal mode polarizations are exactly linear or orientations of two polarization ellipses coincide with each other. For each of these frequencies there exists a direction of propagation for which the two normal modes are linearly polarized, and their polarizations and absorption coefficients fully coincide. The unusual properties of the normal modes should manifest themselves in the spectra, angular distribution, and polarization of the thermallike radiation emitted from surface layers of neutron stars.
 Publication:

The Astrophysical Journal
 Pub Date:
 September 1996
 DOI:
 10.1086/177787
 arXiv:
 arXiv:astroph/9512081
 Bibcode:
 1996ApJ...469..373B
 Keywords:

 ATOMIC PROCESSES;
 MAGNETIC FIELDS;
 STARS: PULSARS: GENERAL;
 STARS: ATMOSPHERES;
 STARS: NEUTRON;
 POLARIZATION;
 Astrophysics
 EPrint:
 LaTeX uses AAS macros, 30 pages, 8 postscript figures in a separate file