Spectropolarimetry of the iron low ionization broad absorption line quasar Q 0059-2735

We present optical (ultraviolet rest-frame) spectropolarimetric observations of the rare iron low ionization broad absorption line (BAL) QSO Q 0059-2735. The continuum polarization increases to the blue with a regular rotation of the polarization position angle, suggesting that at least two mechanisms are at the origin of the polarization. There is also some evidence for dilution by a ion {Fe}{ii} pseudo-continuum in emission. In the broad absorption lines, the polarization strongly rises, with the largest values ever reported. On the contrary, the ion {Fe}{ii} blends in absorption are not more polarized than the continuum, while they are clearly visible in the polarized flux. These different polarization properties of ion {Fe}{ii} absorption lines suggest a different origin and/or geometry. The observed properties of Q 0059-2735 are consistent with a hybrid QSO / starburst model. Based on observations collected at the European Southern Observatory, La Silla, Chil