White Paper on GEMS Study of Polarized X-rays from Neutron Stars. (arXiv:1301.5514v2 [astro-ph.HE] UPDATED)

White Paper on GEMS Study of Polarized X-rays from Neutron Stars. (arXiv:1301.5514v2 [astro-ph.HE] UPDATED):
We examine the expected X-ray polarization properties of neutron-star X-ray
sources of various types, e.g., accretion and rotation powered pulsars,
magnetars, and low-mass X-ray binaries. We summarize the model calculations
leading to these expected properties. We describe how a comparison of these
with their observed properties, as inferred from GEMS data, will probe the
essential dynamical, electromagnetic, plasma, and emission processes in
neutron-star binaries, discriminate between models of these processes, and
constrain model parameters. An exciting goal is the first observational
demonstration in this context of the existence of vacuum resonance, a
fundamental quantum electrodynamical phenomenon first described in the 1930s.