Quantum Plasmas in Neutron Stars

Observations of X-rays from 1E1207.4-5209 (an isolated hot neutron star/pulsar in the supernova remnant KS1209-52) reveal that its X-ray spectrum contains absorption features that display quantization in their energy. We show that such features can be explained by quantizing the Larmor orbits in the extremely strong magnetic field of the neutron star. However, the magnetic field strength necessary to explain the quantized absorption features \underline {(8x10}$^{10}$ \underline {G)} is a factor 40 too small to explain the known rotational spin-down rate of the pulsar \underline {(2-3x10}$^{12}$ G). We provide a solution to this dilemma by showing that X-ray emission arises from confined torodial plasma surrounding the equator of the neutron star/pulsar (a ``pulsarsphere''). This emission is then situated well above the surface of the neutron star and hence reveals a much lower apparent magnetic field strength.