Unusual Broad Absorption Line Quasars from the Sloan Digital Sky Survey

The Sloan Digital Sky Survey has confirmed the existence of populations ofbroad absorption line (BAL) quasars with various unusual properties. We presentand discuss twenty-three such objects and consider the implications of theirwide range of properties for models of BAL outflows and quasars in general. Wehave discovered one BAL quasar with a record number of absorption lines. Twoother similarly complex objects with many narrow troughs show broad MgIIabsorption extending longward of their systemic host galaxy redshifts. This canbe explained as absorption of an extended continuum source by therotation-dominated base of a disk wind. Five other objects have absorptionwhich removes an unprecedented ~90% of all flux shortward of MgII. Theabsorption in one of them has varied across the ultraviolet with an amplitudeand rate of change as great as ever seen. This same object may also show broadH-beta absorption. Numerous reddened BAL quasars have been found, including atleast one reddened mini-BAL quasar with very strong FeII emission. The fivereddest objects have continuum reddenings of E(B-V)~0.5, and in two of them wefind strong evidence that the reddening curve is even steeper than that of theSMC. We have found at least one object with absorption from FeIII but not FeII.This may be due to a high column density of moderately high-ionization gas, butthe FeIII level populations must also be affected by some sort of resonance.Finally, we have found two luminous, probably reddened high-redshift objectswhich may be BAL quasars whose troughs partially cover different regions of thecontinuum source as a function of velocity.