Astrophysical Polarimetry of Cosmological Sources

Kostelecky and Mewes have recently shown that sensitive constraints can be placed on some aspects of Lorentz symmetry violation using certain astronomical data on high-redshift sources. Here, I introduce that data in its astronomical context, making it clear that these data are robust and accurate for their purpose. In particular, I explain that spatially extended scattered light from obscured quasars leads to a centrosymmetric scattering polarization, with polarization position angle independent of wavelength. Evidentally, these relationships aren't spoiled by propagation effects as the photons cross the universe.