The physical nature of polar broad absorption line quasars

In a recent article of Zhou et al., it has been shown, based on radio-variability arguments, that some BALQSOs (broad absorption line quasars) are viewed along the polar axis (orthogonal to accretion disk). These arguments are based on the brightness temperature T-b exceeding 10(12) K, which leads to the well-known inverse Compton catastrophe unless the radio jet is relativistic and is viewed along its axis. In this Letter, we expand the Zhou et al. sample of polar BALQSOs to the entire SDSS DR5 (Sloan Digital Sky Survey Data Release 5). In the process, we clarify a mistake in their calculation of the brightness temperature. The expanded sample of high T-b BALQSOs has an inordinately large fraction of LoBALQSOs (low-ionization BALQSOs). We consider this an important clue to understanding the nature of the polar BALQSOs. This is expected in the polar BALQSO analytical/numerical models of Punsly, in which LoBALQSOs occur when the line of sight is very close to the polar axis, where the outflow density is the highest.