Intranight optical variability of radio-loud broad absorption line quasars

Abstract

We present the results of an optical photometric monitoring programme of 10 extremely radio-loud broad absorption lines (RL-BALQSOs) with radio-loudness parameter, R, greater than 100 and magnitude gi < 19. Over an observing run of about 3.5–6.5 h we found a clear detection of variability for one of our 10 RL-BALQSOs with the intranight optical variability duty cycle of 5.1 per cent, while on including the probable variable cases, a higher duty cycle of 35.1 per cent is found; which is very similar to the duty cycle of radio-quiet broad absorption line (BAL) quasars. This low duty cycle of clear variability per cent in radio-loud subclass of BALQSOs can be understood under the premise where BALs outflow may arise from large variety of viewing angles from the jet axis or perhaps being closer to the disc plane.