# Are there broad absorption-line blazars?

## TL;DR

This study conducted the first systematic search for blazars among broad-absorption-line quasars using optical monitoring, finding no evidence of blazar-like variability, thus challenging the polar model hypothesis for BAL quasars.

## Contribution

It provides the first systematic optical variability analysis of BAL quasars to test for blazar characteristics, with results contradicting the presence of blazars in this class.

## Key findings

- No intra-night optical variability detected in BAL quasar candidates.
- Normal blazars show high duty cycle of INOV, unlike BAL candidates.
- Results challenge the polar model hypothesis for BAL quasars.

## Abstract

We report the first systematic search for blazars among broad-absorption-line (BAL) quasars. This is based on our intranight optical monitoring of a well-defined sample of 10 candidates selected on the criteria of a flat spectrum and an abnormally high linear polarization at radio wavelengths. A small population of BAL blazars can be expected in the 'polar model' of BAL quasars. However, no such case is found, since none of our 30 monitoring sessions devoted to the 10 candidates yielded a positive detection of intra-night optical variability (INOV), which is uncharacteristic of blazars. This lack of INOV detection contrasts with the high duty cycle of INOV observed for a comparison sample of 15 'normal' (i.e., non-BAL) blazars. Some possible implications of this are pointed out.