SDSS quasars with PV broad absorption

Understanding the nature of these flows requires further constraints on their physical properties, including their column densities, for which well-studied BALs, such as CIV {lambda}{lambda}1548,1551, typically provide only a lower limit because of saturation effects.

Low-abundance lines, such as PV {lambda}{lambda}1118,1128, indicate large column densities, implying that outflows more powerful than measurements of CIV alone would indicate. We search through a sample of 2694 BAL quasars from the Sloan Digital Sky Survey III/Baryon Oscillation Spectroscopic Survey data release 9 quasar catalogue for such absorption, and we identify 81 'definite' and 86 'probable' detections of PV broad absorption, yielding a firm lower limit of 3.0-6.2 per cent for the incidence of such absorption among BAL quasars.