Broad Absorption Line Quasars and the Radio-Loud/Radio-Quiet Dichotomy

Abstract

The observation that the extremely broad, blueshifted absorption troughs which characterize broad absorption line quasars (BALQs) occur exclusively in radio-quiet quasars (RQQs) suggests that this class of active galactic nuclei (AGN) may offer important clues to the radio-loud/radio-quiet (RL/RQ) dichotomy in quasars. Interestingly, there is also substantial observational evidence for similar, but lower velocity intrinsic absorption outflows in some Seyferts and radio-loud quasars (RLQs) as well. Theoretically, however, it is difficult to interpret this broad range of mass ejection phenomena in the context of the standard model for BALQs. Thus, a new model is considered here in which the thermal gas producing the blueshifted absorption troughs is associated with a poorly collimated outflow of weakly radio-emitting plasma -- in essence, a weak jet. This model provides an appropriate framework not only for assessing the possible connection between the BAL phenomenon in RQQs and related intrinsic absorption outflows in stronger radio sources and in less luminous sources, both of which are known to possess jet-like radio structure, but also for understanding the RL/RQ dichotomy in light of recent observations which indicate that at least some RQQs possess central engines that are capable of producing weak versions of the powerful radio jets characteristic of RLQs.