A comparative study of the intra-night optical variability of powerful AGNs

Abstract

In order to address a currently much debated issue, we are carrying out a systematic search for intra-night optical micro-variability in major classes of powerful (M'II ~ -23.0 mag) active galactic nuclei (AGNs). Our sample includes 7 sets of AGNs, covering narrow redshift bins across the range 0.18 :5 z :5 2.2. Each set cOllBists of a radio-quiet quasar, a radio lobe-dominated quasar, a BL Lac object and/or a radio core-dominated quasar (blazar), all having ffl'll '" 16 mag. The observatiollB were made primarily using the lO4-cm telescope of State Observatory, Nainital. The monitoring completed so far ("'" 90 nlghts) clearly indicates that, compared to the other AGN types, BL Lacs are distinctly more prone to exhibit intra-night optical variatiollB.