Probing broad absorption line quasar outflows: X-ray insights

Energetic outflows appear to occur in conjunction with active mass accretion onto supermassive black holes. These outflows are most readily observed in the ∼10% of quasars with broad absorption lines, where the observer's line of sight passes through the wind. Until fairly recently, the paucity of X-ray data from these objects was notable, but now sensitive hard-band missions such as Chandra and XMM-Newton are routinely detecting broad absorption line quasars. The X-ray regime offers qualitatively new information for the understanding of these objects, and these new results must be taken into account in theoretical modeling of quasar winds.