Studying the Population of Radio-Loud Broad Absorption Line Quasars (BAL QSOs) from the Sloan Digital Sky Survey

Broad Absorption Lines (BALs) seem to be the most extreme manifestations of quasar (QSO) outflows. Two main scenarios have been proposed to explain the nature of BAL QSOs. They may be a physically distinct population (e.g. newborn or recently refueled QSOs) or present in all QSOs but intercepted by only a fraction of the lines of sight to the QSOs. Our previous observations of a sample of 15 radio BAL QSOs show that they have convex radio spectra typical of GigaHertz Peaked-Spectrum (GPS) sources. We have selected a well-defined sample of radio bright BAL QSOs from the Sloan Digital Sky Survey-Data Release 5. Here we present preliminary results on radio continuum observations in full polarization of this sample, taken with the 100m Effelsberg radiotelescope at 2.7, 4.8, 8.4 and 10.5GHz. The aim is to describe the radio spectra and polarization characteristics of these radio bright BAL QSOs and compare them with our previous results from the study of a radio fainter sample of BAL QSOs and with the properties of normal QSOs where the BAL phenomenon is not seen.