Schwarzschild electrodynamics: Black holes, neutron stars

• Published in: Astrophysics and space science 1978-06, Vol.56 (1), p.129-190
• Main Authors: Kearney, Michael W., Kegeles, Lawrence S., Cohen, Jeffrey M.
• Format: Article
• Language: English
• ISSN: 0004-640X; 1572-946X
• DOI: 10.1007/BF00643467

Electromagnetic perturbations of the exterior Schwarzschild metric are investigated. Power-series solutions for the radial dependence of the electromagnetic field in the strong gravitational field exterior to a nonrotating black hole or neutron star are used to solve a problem concerning the scattering of a linearly polarized electromagnetic plane wave from a Schwarzschild black hole as well as the problem of a radially vibrating spherical neutron star with a frozen-in magnetic field. Expressions for the total elastic scattering and absorption cross sections are obtained for the black-hole problem. The radiation induced by neutron-star vibrations is determined, and it is found that general-relativistic effects on the radiated power can be very important for typical neutron-star parameters. Specifically, it is shown that the star is hyperemissive (i.e., the power radiated is in excess of the flat-space result) for all values of frequency above a certain limit, that the radiation is hyperemissive for all frequencies in the dipole case, and that the radiation is hypoemissive below a fixed frequency for higher multipoles.