The nature of the intra-night optical variability in blazars

TL;DR

This study presents short-term optical monitoring of 13 blazars, revealing mostly slow, smooth variations with rare rapid changes, and hints of quasi-periodic oscillations, contributing to understanding blazar variability mechanisms.

Contribution

It provides new observational data on intra-night optical variability in blazars, highlighting the rarity of rapid changes and potential quasi-periodic oscillations.

Findings

Most variations are slow and linear, up to 0.1 mag/hour.

Only about 2% chance to observe >0.1 mag/hour variability.

Hints of low-amplitude quasi-periodic oscillations in some objects.

Abstract

In this paper we present results of a short-term optical monitoring of 13 blazars. The objects were monitored mostly in the R-band for a total of ~ 160 hours between 2006 and 2011. We study the nature of the short-term variations and show that most of them could be described as slow, smooth, and (almost) linear changes of up to ~ 0.1 mag/hour, but many objects show no short-term variations at all. In fact, we found only ~ 2 per cent chance to observe variability of more than 0.1 mag/hour for the sample we observed. Hints for quasi-periodic oscillations at very low amplitude levels are also found for some objects. We briefly discuss some of the possible mechanisms to generate the intra-night variability and the quasi-periodic oscillations.