Unveiling the physics behind the spectral variations of "changing-look"
  quasars with optical polarimetry
  A handful of active galactic nuclei (AGN) have shown strong spectral
variations in the optical band between epochs that are years apart. The
appearance or disappearance of broad emission lines in their spectra completely
changes their classification. Since their nucleus orientation cannot change in
such short timescales another physical interpretation has to be found. Several
scenarios are competing to explain their changing-look nature and, for the
first time, we conduct polarized radiative transfer Monte Carlo simulations for
all the models. We demonstrate that all interpretations have distinctive
features in both total optical flux and continuum polarization such as proposed
by Hutsem\'ekers and collaborators. Distinguishing between the different
scenarios is thus straightforward. We apply our results on the changing-look
quasar J1011+5442 and confirm the conclusions found by Hutsem\'ekers and
collaborators: in this specific case, the disappearance of the broad emission
lines is due to a change in accretion rate.
