Polarimetry and the High-Energy Emission Mechanisms in Quasar Jets
  The emission mechanisms in extragalactic jets include synchrotron and various
inverse-Compton processes. At low (radio through infrared) energies, it is
widely agreed that synchrotron emission dominates in both low-power (FR I) and
high-power (FR II and quasar) jets, because of the power-law nature of the
spectra observed and high polarizations. However, at higher energies, the
emission mechanism for high-power jets at kpc scales is hotly debated. Two
mechanisms have been proposed: either inverse-Compton of cosmic microwave
background photons or synchrotron emission from a second, high-energy
population of electrons. Here we discuss optical polarimetry as a method for
diagnosing the mechanism for the high-energy emission in quasar jets, as well
as revealing the jet's three-dimensional energetic and magnetic field
structure. We then discuss high-energy emission mechanisms for powerful jets in
the light of the HST polarimetry of PKS 1136-135.
